Treatment of gerd

Abstract

An implantable medical device for treating reflux disease, the implantable medical device comprising a movement restriction device (110) configured to be fixated to the stomach wall for hindering movement of the lower esophageal sphincter relative to the thoracic diaphragm. The movement restriction device comprises central part (111e), and at least two outer parts (111a-d) configured to be connected to each other along a vertical plane. The at least two outer parts are configured to be connected to the central part for forming at least a portion of a functional movement restriction device. The central part comprises at least one horizontally extending rim (151h1-4) and the central part has a contacting surface configured to contact at least one surface of the at least two outer parts, and wherein a portion of the horizontally extending rim is wedge-shaped with an angle in the range 20° - 60°.

Description

TREATMENT OF GERDTECHNICAL FIELDThe present inventive concept generally relates to medial implants. More specifically the inventive concept relates to medical implants for treating gastroesophageal reflux disease (GERD). BACKGROUNDGastroesophageal reflux disease (GERD), or reflux disease, is a condition resulting in mucosal damage in the esophagus caused by recurring occurrence of acid reflux in the esophagus. GERD can be treated in a number of different ways, including both medical and surgical treatments. An example of a surgical treatment is Nissen fundoplication surgery, in which the upper curve of the stomach (the fundus) is wrapped around the lower esophageal sphincter (LES) to strengthen the sphincter, prevent acid reflux, and repair a hiatal hernia. This method however risks causing a constriction of the food passageway, making it more difficult for the patient to swallow.Another example is the Anglechik prosthesis, in which a device formed like a horseshoe is placed around the esophagus above the cardia. The intended effect is to prevent the cardia from slipping up into the thorax cavity. However, this device is associated with a number of complications, including migrating through and damaging the esophagus. Further, the body tends to react to a medical implant, partly because the implant is a foreign object, and partly because the implant interacts mechanically with tissue of the body. Exposing tissue to long-term engagement with, or pressure from, an implant may deprive the cells of oxygen and nutrients, which may lead to deterioration of the tissue, atrophy and eventually necrosis. It would therefore be advantageous to provide more efficient and / or less damaging techniques for treating GERD.  SUMMARYIt is an object of the present inventive concept to overcome, or at least alleviate, at least some of the drawbacks associated with the above-mentioned treatments of GERD. Further and / or alternative objectives may be understood from the following.A method for treating reflux disease of a human patient by implanting a movement restriction device is provided. The movement restriction device is arranged to restrict movement of the cardia of the patient’s stomach towards the diaphragm to hinder the cardia from sliding through the diaphragm opening into the patient’s thorax. The method comprises attaching the fundus of the stomach of the patient to the esophagus of the patient in a first position, attaching the fundus of the stomach of the patient to the esophagus of the patient in a second position, at a distance from the first position in a cranial-caudal direction, and positioning the movement restriction device between the first and second position, such that the movement restriction device is secured in the cranial-caudal direction by the attachments between the fundus and the esophagus in the first and second positions.According to one embodiment, the step of attaching the fundus of the stomach of the patient to the esophagus of the patient in a second position is preceded by the step of positioning the movement restriction device between the first and second position.According to one embodiment, at least one of the steps of: attaching the fundus of the stomach of the patient to the esophagus of the patient in a first position, and attaching the fundus of the stomach of the patient to the esophagus of the patient in a second position comprises suturing or stapling the fundus to the esophagus.According to one embodiment, the steps of attaching the fundus of the stomach of the patient to the esophagus of the patient in a first position and attaching the fundus of the stomach of the patient to the esophagus of the patient in a second position are preceded by the step of dissecting the stomach of the patient.According to one embodiment, at least one of the steps of attaching the fundus of the stomach of the patient to the esophagus of the patient in a first position and attaching the fundus of the stomach of the patient to the esophagus of the patient in a second position is performed using a translaminar instrument configured to be inserted through the esophagus of the patient.According to one embodiment, the step of positioning the movement restriction device between the first and second position is performed using an abdominal instrument configured to enter the abdomen of the patient through an incision made in the skin of the patient.At least one of the steps of attaching the fundus of the stomach of the patient to the esophagus of the patient in a first position and attaching the fundus of the stomach of the patient to the esophagus of the patient in a second position may be performed using an abdominal instrument configured to enter the abdomen of the patient through an incision made in the skin of the patient.The step of attaching the fundus of the stomach of the patient to the esophagus of the patient in a first position may comprise attaching the fundus of the stomach of the patient to the esophagus of the patient at a distance from the angle of His exceeding 5mm, or exceeding 10mm, or exceeding 20mm or exceeding 30mm.The step of positioning the movement restriction device between the first and second position may comprise positioning the center of mass of the movement restriction device in a plane extending perpendicular to the cranial – caudal direction at a distance from the angle of His exceeding 20mm, or exceeding 30mm.The step of positioning the movement restriction device between the first and second position may comprise positioning the upper-most point of the movement restriction device in a plane extending perpendicular to the cranial – caudal direction at a distance from an upper-most point of the cardia exceeding 5mm, or exceeding 10mm.The step of positioning the movement restriction device between the first and second position may comprise positioning the center of mass of the movement restriction device in a plane extending perpendicular to the cranial – caudal direction at a distance from an upper-most point of the cardia exceeding 1mm, or exceeding 5mm, or exceeding 10mm.The movement restriction device may in any of the embodiments herein have a rounded shape, which may be a spherical shape.The step of positioning the movement restriction device may comprise positioning a movement restriction device encircling at least 1 / 3 of the esophagus in a plane extending perpendicular to the cranial – caudal direction, or positioning a movement restriction device encircling at least 1 / 2 of the esophagus in a plane extending perpendicular to the cranial – caudal direction, or positioning a movement restriction device encircling at least 2 / 3 of the esophagus in a plane extending perpendicular to the cranial – caudal direction, or positioning a movement restriction device encircling the esophagus in a plane extending perpendicular to the cranial – caudal direction.The step of positioning the movement restriction device may comprise positioning a movement restriction device comprising a curved outer surface, such that the curved outer surface faces the esophagus. The curved outer surface may comprise a radius of curvature corresponding to or exceeding the radius of curvature of the esophagus, such that the curved outer surface comprises a radius of curvature corresponding to or exceeding the radius of curvature of the esophagus.The step of positioning the movement restriction device may comprise positioning a movement restriction device comprising an electrode arrangement configured to electrically stimulate muscle tissue of the portion of the fundus and / or the serosa to improve the conditions for long term implantation of the movement restriction device.The method may in any of the embodiments comprise implanting an implantable energy source configured to provide the electrode with electrical power. The implantable energy source may be arranged inside the movement restriction device or may be placed subcutaneously. The method may further comprise implanting an implantable charger configured to be electrically connected to the implantable energy source and enable charging of the implantable energy source by the external energy source.The method may further comprise implanting a controller configured to be operably connected to the electrode arrangement for controlling the electrical stimulation of the muscle tissue. The controller may be configured to control the electrical stimulation such that the muscle tissue is stimulated by a series of electrical pulses PL1, PL2, PL3, PL4. The electrical stimulation signal may comprise a pulse frequency of 0.15-0.25 Hz, a pulse duration of 20-30 ms and a pulse amplitude of 3-10 mA. The controller may comprise a wireless remote control.According to one embodiment, the step of positioning the movement restriction device comprises positioning a movement restriction device having a constricting state for hindering fluid from passing from the stomach into the esophagus and an expanded state for allowing food to pass into the stomach in response to the patient swallowing. The step of positioning the movement restriction device may comprise positioning a movement restriction device configured to exert an encircling pressure on the esophagus in the constricting state.According to one embodiment, the step of positioning the movement restriction device comprises positioning a movement restriction device comprising at least one attractor for resiliently attracting adjacent portions of the movement restriction device to generate the encircling pressure. The attractor may comprise an elastic element or at least two mutually attracting magnets. The apparatus may further comprise a link connecting a first and a second one of said at least two magnets to each other.The step of positioning the movement restriction device may comprise positioning a non-adjustable movement restriction device or in the alternative the step of positioning the movement restriction device may comprises positioning a movement restriction device having an adjustable volume.An apparatus for treating reflux disease of a human patient is further provided. The apparatus comprises an implantable movement restriction device having a shape and size allowing it to be arranged to rest against a fundus wall portion of the patient’s stomach, such that the movement restriction device is implanted at a position between the patient’s diaphragm and a portion of the fundus wall, and such that movement of the cardia of the patient’s stomach towards the diaphragm is restricted to hinder the cardia from sliding through the diaphragm opening into the patient’s thorax. The apparatus further comprises a first electrode arrangement configured to engage and electrically stimulate muscle tissue of the fundus wall portion to exercise the muscle tissue to improve the conditions for long term implantation of the movement restriction device, and a second electrode arrangement configured to engage and electrically stimulate the cardiac sphincter for causing contraction of the cardiac sphincter.According to one embodiment, the first electrode arrangement is arranged on an outer surface of the movement restriction device. The first electrode arrangement may comprise a plurality of electrode elements, each of which being configured to engage and electrically stimulate the muscle tissue.The first electrode arrangement may comprise a coiled wire for increasing a contact surface between the first electrode arrangement and the muscle tissue and for allowing the first electrode arrangement to follow contraction and relaxation of the muscle tissue.At least one of the first and second electrode arrangement may comprise a bare electrode portion configured to form a metal-tissue interface with the muscle tissue, thereby allowing faradaic charge transfer to the be predominant charge transfer mechanism over said interface.At least one of the first and second electrode arrangement may comprise an electrode portion at least partly covered by a dielectric material configured to form a dielectric-tissue interface with the muscle tissue, thereby allowing for a faradaic portion of the charge transfer mechanism over said interface to be reduced.According to one embodiment, the second electrode arrangement comprises at least two electrode elements configured to be arranged on opposing sides of the cardiac sphincter.The apparatus may further comprise a holder configured to support the at least two electrode elements at the opposing sides of the cardiac sphincter.According to one embodiment, the apparatus may further comprise an implantable energy source configured to provide the electrode with electrical power. The implantable energy source may be arranged inside the movement restriction device or outside the movement restriction device, such as subcutaneously. The implantable energy source may comprises a primary cell and / or a secondary cell.The apparatus in any of the preceding embodiments may further comprise a controller configured to be operably connected to the electrode arrangement for controlling the electrical stimulation of the muscle tissue. The controller may be configured to control the electrical stimulation such that the muscle tissue is stimulated by a series of electrical pulses PL1, PL2, PL3, PL4. The controller may be configured to control the electrical stimulation such that a pulse of a first polarity is followed by a pulse of a second, reversed polarity.According to one embodiment, the controller is configured to generate a pulsed electrical stimulation signal comprising a pulse frequency F of 0.01-150 Hz.According to one embodiment, the electrical stimulation signal comprises a pulse duration D of 0.01-100 ms.According to one embodiment, the electrical stimulation signal comprises a pulse amplitude A of 1-15 mA.According to one embodiment, the electrical stimulation signal comprises a pulse frequency of 0.15-0.25 Hz, a pulse duration of 20-30 ms and a pulse amplitude of 3-10 mA.The electrical stimulation signal may comprise a build-up period X1 of 0.01-2 s in which the amplitude is gradually increasing, a stimulation period X2 of 1-60 s, and a stimulation pause X4 of 0.01-60 s, wherein the electrical signal comprises a pulse frequency of 1-50 Hz and a pulse duration of 0.1-10 ms.The controller may comprise a wireless remote control and the controller may be configured to indicate a functional status of the implantable energy source. The functional status may indicate a charge level of the implantable energy source.According to one embodiment, the functional status indicates a temperature of at least one of the implantable energy source, the muscle tissue and the electrode arrangement.According to one embodiment, the implantable energy source is configured to be charged by an external energy source arranged outside the patient’s body.According to one embodiment, the apparatus further comprises an implantable charger configured to be electrically connected to the implantable energy source and enable charging of the implantable energy source by the external energy source.The charger may comprise an electromagnetic coil configured to receive electrical power wirelessly from the external energy source, and the charger may be configured to control the charging of the implantable energy source based on the functional status.According to one embodiment, the charger is configured to control the charging of the implantable energy source by controlling a receipt of electrical power from the external energy source at the implantable charger.According to one embodiment, the charger is configured to control the charging of the implantable energy source by controlling a transmission of electrical power from the external energy source to the implantable charger.The apparatus may further comprise an implantable sensor S1 configured to sense actions potentials generated by pacemaker cells of the muscle tissue, and wherein the controller is configured to control the electrical simulation based at least partly on the sensed action potentials, and according to one embodiment, the controller is configured to generate electrical pulses amplifying the sensed action potentials.The volume of the movement restriction device may be non-adjustable after implantation, in the alternative, a volume of the movement restriction device is adjustable after implantation.The movement restriction device may further comprise an injection port for allowing a fluid to be injected or extracted from the inside of the movement restriction device so as to vary a volume of the movement restriction device after implantation.The movement restriction device may comprise a biocompatible outer surface configured to rest against the fundus wall portion.The movement restriction device may be substantially spherical or egg-shaped.The movement restriction device may be configured to be at least partially invaginated by the fundus wall.The movement restriction device in any of the embodiment herein may be configured to be introduced in the patient’s body by means of a gastroscope or an intraluminal instrument.The movement restriction device may be configured to change its shape to allow it to pass through a trocar during insertion into the patient’s body.According to one embodiment, the movement restriction device is formed of at least two distinct and separable parts configured to be assembled into the movement restriction device after insertion in the patient’s body.A minimum width of the movement restriction device in any of the embodiments herein, as measured from side to side, may be 20mm or larger, or 30 mm or larger, such as 40 mm or larger.A minimum outer circumference of the movement restriction device may be 150 mm or less, such as 130 mm or less, such as 110 mm or less, such as 90 mm or less, such as 70 mm or less, such as 50 mm or less, such as 30 mm or less.An apparatus for treating reflux disease of a human patient is further provided. The apparatus comprises an implantable movement restriction device configured to be fixated between an upper portion of the stomach and the thoracic diaphragm of the patient, for restricting the movement of the cardia of the patient towards the thoracic diaphragm. The implantable movement restriction device has a first cross-sectional distance and a second cross-sectional distance, and the movement restriction device is configured to be implanted such that the first cross-sectional distance is more parallel than perpendicular to the cranial-caudal axis of the patient, and the second cross-sectional distance is more perpendicular than parallel to the cranial-caudal axis of the patient. The implantable movement restriction device is adjustable in situ, such that the shape of the implantable movement restriction device can be adjusted by the adjustment of the length of the first cross-sectional distance, such that the length of the first cross-sectional distance can be increased relative to the length of the second cross-sectional distance.According to one embodiment, the shape of the implantable movement restriction device can be adjusted by an increase of the length of the first cross-sectional distance relative to the length of the second cross-sectional distance while the length of a circumference of a cross-section of the implantable movement restriction device, in a plane parallel to the coronal plane of the patient remains constant.According to one embodiment, the shape of the implantable movement restriction device can be adjusted to an elongated shape by an increase of the length of the first cross-sectional distance relative to the length of the second cross-sectional distance.According to one embodiment, the shape of the implantable movement restriction device can be adjusted by an increase of the length of the first cross-sectional distance relative to the length of the second cross-sectional distance, such that the length of the circumference of a cross-section of the implantable movement restriction device, in a plane parallel to the coronal plane of the patient, is increased relative to the length of the circumference of a cross-section of the implantable movement restriction device, in a plane parallel to the transverse plane of the patient.According to one embodiment, the implantable movement restriction device comprises a lower portion configured to, directly or indirectly, engage the stomach of the patient in a region of the angle of his, such that the function of the implantable movement restriction device is supported by tissue of the stomach in the region of the angle of his.According to one embodiment, the implantable movement restriction device comprises an upper portion configured to, directly or indirectly, engage the thoracic diaphragm of the patient, and wherein the upper portion comprises at least one curvature. According to one embodiment, the implantable movement restriction device is configured to be at least partially invaginated by the stomach wall.The implantable movement restriction device may be configured to be at least partially invaginated by the stomach wall of the fundus.According to one embodiment, the movement restriction device comprises a curved cross-section in a plane parallel to the transverse plane of the patient. The curve may be configured to partially enclose the esophagus of the patient. According to one embodiment, the movement restriction device is configured to encircle at least 1 / 3 of the esophagus in a plane parallel to the transverse plane of the patient, in another embodiment, the movement restriction device is configured to encircle at least 1 / 2 of the esophagus in a plane parallel to the transverse plane of the patient, in another embodiment, the movement restriction device comprises a C-shaped cross-section in a plane parallel to the transverse plane of the patient, and the C-shaped cross-section is configured to partially enclose the esophagus of the patient, in another embodiment, the movement restriction device is configured to encircle at least 2 / 3 of the esophagus in a plane parallel to the transverse plane of the patient.According to one embodiment, a cross-section of the movement restriction device in a plane parallel to the transverse plane of the patient comprises a closed curve configured to enclose the esophagus of the patient. According to one embodiment, the movement restriction device is hydraulically adjustable. The movement restriction device may comprise a conduit configured to connect the hydraulically adjustable movement restriction device to an implantable injection port.The movement restriction device may comprise an injection port, such that the hydraulically adjustable movement restriction device can be adjusted by the injection or withdrawal of a hydraulic fluid into the hydraulically adjustable movement restriction device. A portion of the movement restriction device may comprise a bellows, and wherein the injection or withdrawal of a hydraulic fluid into the hydraulically adjustable movement restriction adjusts a length of the bellows. According to one embodiment, the movement restriction device comprises a wall enclosing a hydraulic adjustment chamber, and the thickness of the wall varies, which affects the alteration of the shape of the movement restriction device as fluid is injected into or withdrawn from the movement restriction device. According to one embodiment, the shape of the movement restriction device is altered by a thinner portion of the wall enclosing the hydraulic adjustment chamber being deformed more than thicker portions of the wall enclosing the hydraulic adjustment chamber. According to one embodiment, the movement restriction device is mechanically adjustable and may comprise a mechanical operation device.According to one embodiment, the movement restriction device comprises a transferring element configured to transfer at least one of: electrical energy, and mechanical force to the mechanically adjustable movement restriction device.According to one embodiment, the transferring element comprises at least one of: an electrical lead, a shaft for transferring rotating force, and a shaft for transferring linear force.According to one embodiment, the mechanical operation device comprises an electrical motor. The mechanical operation device may comprise a transmission configured to transform a rotating force generated by the electrical motor into a linear force for adjusting the length of the first cross-sectional distance.According to one embodiment, a portion of the movement restriction device comprises a bellows, and operation of the mechanical operation device adjusts a length of the bellows. In other embodiments, the movement restriction device is electrically adjustable.According to one embodiment, the movement restriction device comprises at least one material configured to alter shape when exposed to an electrical current or an electrical voltage. Such a material may comprise at least one electroactive polymer which could be an electroactive polymer selected from a list consisting of: ferroelectric polymers, electrostrictive graft polymers, electrostrictive paper, piezoelectric polymers and liquid crystal elastomers. According to one embodiment, the movement restriction device further comprises a transferring element configured to transfer electrical energy to the movement restriction device.According to one embodiment, the length of the first cross-sectional distance is adjustable in situ such that the length of the first cross-sectional distance is 1,2 times the length of the second cross-sectional distance, or 1,3 times the length of the second cross-sectional distance, or 1,5 times the length of the second cross-sectional distance.According to one embodiment, the length of the first cross-sectional distance is adjustable in situ such that the length of the circumference of a cross-section of the implantable movement restriction device, in a plane parallel to the coronal plane of the patient, is 1,2 times the length of the circumference of a cross-section of the implantable movement restriction device, in a plane parallel to the transverse plane of the patient, or 1,3 times the length of the circumference of a cross-section of the implantable movement restriction device, in a plane parallel to the transverse plane of the patient, or 1,5 times the length of the circumference of a cross-section of the implantable movement restriction device, in a plane parallel to the transverse plane of the patient.According to one embodiment, the length of the first cross-sectional distance is adjustable in situ such that the center of mass of the movement restriction device in a plane parallel to the transverse plane of the patient is positioned at a distance from the angle of His exceeding 20mm, or exceeding 30mm.According to one embodiment, the length of the first cross-sectional distance is adjustable in situ such that the center of mass of the movement restriction device in a plane parallel to the transverse plane of the patient is positioned at a distance from an upper-most point of the cardia exceeding 5mm, or exceeding 10mm.In any of the embodiments herein, the movement restriction device may comprise at least two parts.In any of the embodiments herein, the apparatus may further comprise an implantable energy source configured to provide the adjustable implantable movement restriction device with electrical power. The implantable energy source may be arranged inside the movement restriction device or arranged subcutaneously. In any of the embodiments herein, the apparatus may further comprise at least one electrode for electrically stimulating at least one tissue portion of the patient. According to one embodiment, the movement restriction device comprises has a constricting state for hindering fluid from passing from the stomach into the esophagus and an expanded state for allowing food to pass into the stomach in response to the patient swallowing. The movement restriction device may comprise at least one attractor for resiliently attracting adjacent portions of the movement restriction device to generate an encircling pressure on the esophagus and the attractor may comprise an elastic element.According to one embodiment, the attractor comprises at least two mutually attracting magnets.An apparatus for treating reflux disease of a human patient is further provided. The apparatus comprises an implantable movement restriction device configured to be fixated between an upper portion of the stomach and the thoracic diaphragm of the patient, for restricting the movement of the cardia of the patient towards the thoracic diaphragm. The implantable movement restriction device comprises a first portion having a first volume enclosed by material of the implantable movement restriction device, and a second portion, different from the first portion, having a second volume enclosed by material of the implantable movement restriction device. The first volume and the second volumes are equally large and the first volume has a higher density than the second volume, and the second volume has a density below 1000 kg / m3.According to one embodiment, the first volume comprises a first solid material, and the first solid material may comprise a polymer material. According to one embodiment, the first solid material comprises at least one of silicone-based material and a polyurethane-based material. According to one embodiment, the second volume comprises a second solid material, and the second solid material may comprise a polymer material. The second solid material may comprise at least one of a polypropylene-based and a polyethylene-based material.The first volume may comprise a solid material having a density above 1000 kg / m3 and the second volume may comprise a solid material having a density below 1000 kg / m3.According to one embodiment, the second volume comprises a fluid, which may be a liquid having a density a below 1000 kg / m3, such as a liquid selected from a list of oil-based liquids, and alcohol-based liquids.According to one embodiment, the second volume comprises a gas, and the second volume may comprise a plurality of volumes of gas enclosed by an enclosing material.According to one embodiment, the second volume comprises a solid polymer material enclosing the enclosing material, and the enclosing material is harder than the solid polymer material. According to one embodiment, the plurality of volumes of gas enclosed by an enclosing material makes up at least 10 volume percent of the second volume, more preferably at least 20 volume percent of the second volume, and even more preferably at least 30 volume percent of the second volume.The enclosing material may comprise glass. According to one embodiment, the movement restriction device has an average density below 1100 kg / m3, or below 1050 kg / m3, or below 1000 kg / m3.According to one embodiment, the movement restriction device comprises a first cross-sectional distance and a second cross-sectional distance. The movement restriction device may be configured to be implanted such that the first cross-sectional distance is more parallel than perpendicular to the cranial-caudal axis of the patient, and the second cross-sectional distance is more perpendicular than parallel to the cranial-caudal axis of the patient. The implantable movement restriction device may be adjustable in situ, such that the shape of the implantable movement restriction device can be adjusted by the adjustment of the length of the first cross-sectional distance, such that the length of the first cross-sectional distance can be increased relative to the length of the second cross-sectional distance.According to one embodiment, the shape of the implantable movement restriction device can be adjusted by an increase of the length of the first cross-sectional distance relative to the length of the second cross-sectional distance while the length of a circumference of a cross-section of the implantable movement restriction device, in a plane parallel to the coronal plane of the patient remains constant.According to one embodiment, the implantable movement restriction device comprises a lower portion configured to, directly or indirectly, engage the stomach of the patient in a region of the angle of his, such that the function of the implantable movement restriction device is supported by tissue of the stomach in the region of the angle of his.According to one embodiment, the implantable movement restriction device comprises an upper portion configured to, directly or indirectly, engage the thoracic diaphragm of the patient, and wherein the upper portion comprises at least one curvature. The implantable movement restriction device may in any of the embodiments herein be at least partially invaginated by the stomach wall.According to one embodiment, the implantable movement restriction device is configured to be at least partially invaginated by the stomach wall of the fundus.According to one embodiment, the implantable movement restriction device comprises at least one circular cross-section.The implantable movement restriction device may in any of the embodiments herein comprise at least two parts, and the at least two parts may be configured to be assembled to form the implantable movement restriction device. The at least two parts may be configured to be connected to each other to form the implantable movement restriction device.According to one embodiment, the apparatus further comprising an interconnecting part configured to connect to the at least two parts, and at least one of the two parts and the interconnecting part comprises a connecting recess, and at least one of the two parts and the interconnecting part comprises a connecting protrusion, and wherein at least one connecting protrusion and one connecting recess are configured to be interconnected for forming the implantable movement restriction device.According to one embodiment, the movement restriction device comprises a curved cross-section in a plane parallel to the transverse plane of the patient, and wherein the curve is configured to partially enclose the esophagus of the patient.According to one embodiment, the movement restriction device is configured to encircle at least 1 / 3 of the esophagus in a plane parallel to the transverse plane of the patient, or configured to encircle at least 1 / 2 of the esophagus in a plane parallel to the transverse plane of the patient, or configured to encircle at least 2 / 3 of the esophagus in a plane parallel to the transverse plane of the patient.According to one embodiment, the movement restriction device comprises a C-shaped cross-section in a plane parallel to the transverse plane of the patient, and wherein the C-shaped cross-section is configured to partially enclose the esophagus of the patient.According to one embodiment, a cross-section of the movement restriction device in a plane parallel to the transverse plane of the patient comprises a closed curve configured to enclose the esophagus of the patient. According to one embodiment, the movement restriction device has a constricting state for hindering fluid from passing from the stomach into the esophagus and an expanded state for allowing food to pass into the stomach in response to the patient swallowing. The movement restriction device may comprise at least one attractor for resiliently attracting adjacent portions of the movement restriction device to generate an encircling pressure in the esophagus. The attractor may comprise an elastic element or at least two mutually attracting magnets.An apparatus for treating reflux disease of a human patient is further provided. The apparatus comprises an implantable movement restriction device configured to be at least partly invaginated by the stomach wall of the patient for restricting the movement of the cardia of the patient towards the thoracic diaphragm. The implantable movement restriction device has a first cross-sectional distance and a second cross-sectional distance, the first cross-sectional distance has a first length and the second cross-sectional distance has a second length. The first length is more than 1,5 times the second length. The movement restriction device is configured to be implanted such that the first cross-sectional distance is more parallel than perpendicular to the cranial-caudal axis of the patient, and the second cross-sectional distance is more perpendicular than parallel to the cranial-caudal axis of the patient. The implantable movement restriction device comprises at least a first and a second part configured to be connected to form the implantable movement restriction device. The center of gravity of the first part is positioned on a plane extending perpendicularly from a first half of the first cross-sectional distance and the center of gravity of the second part is positioned on a plane extending perpendicularly from a second half of the first cross-sectional distance, a lower portion of the first part comprises a first connecting portion and the upper portion of the second part comprises a second connecting portion. The first and second connecting portions are configured to be connected to each other and the first and second connecting portions are configured to remain connected to each other by at least one of the first and second parts being supported or compressed by the invagination of the implantable movement restriction device in the stomach wall of the patient, and the first and second parts are capable of disconnecting and separating if the support or compression from at least one of the first and second parts the stomach wall decreases.The first and second connecting portions may be configured to be directly connected to each other, or may be configured to be indirectly connected to each other by an interconnecting part.According to one embodiment, at least one of: the first part, the second part, and the interconnecting part comprises a connecting recess, and at least one of: the first part, the second part, and the interconnecting part comprises a connecting protrusion and wherein at least one connecting protrusion and one connecting recess are configured to be interconnected for forming the implantable movement restriction device.According to one embodiment, at least one of the first and second connecting portions comprises a resilient connecting portion and wherein the resilient connecting portion is, directly or indirectly, supported or compressed by the invagination of the implantable movement for connecting, directly or indirectly, the first part to the second part.According to one embodiment, the resilient connecting portion comprises a resilient protrusion configured to engage a recess for connecting, directly or indirectly, the first part to the second part. The resilient protrusion may be configured to connect and disconnect from a recess in a direction substantially perpendicular to the direction of the first cross-sectional distance.According to one embodiment, first part comprises a first sub-part a second sub-part, and / or the second part comprises a first sub-part and a second sub-part. Each of the first and second sub-parts may comprise a connecting portion, and each of the first and second sub-parts may be configured to connect and disconnect from the connecting portion of the first part, or the second part of the interconnecting part in a direction substantially perpendicular to the direction of the first cross-sectional distance.According to one embodiment, the first sub-part and the second sub-part are configured to remain connected to each other by at least one of the first and second parts being supported or compressed by the invagination of the implantable movement restriction device in the stomach wall of the patient, and wherein the first sub-part and the second sub-part are capable of disconnecting from each other and separating if the support or compression from the stomach wall on at least one of the first and second parts decreases.According to one embodiment, the first part comprises a first and second sub-part, and the first and second sub-parts are configured to remain connected by the first and second sub-parts being supported or compressed by the connecting portion of the second part.According to one embodiment, the second part is configured to exert a supporting or compressing force on the first part derived from a supporting or compressing force exerted by the stomach wall on the second part.According to one embodiment, the first part comprises a first sub-part and a second sub-part, and the second part comprises a first sub-part and a second sub-part, and the first and second sub-parts of the first part are configured to remain connected to each other by a supporting or compressing force exerted by at least one of the second part and the stomach wall. The first and second sub-parts of the second part are configured to remain connected to each other by a supporting or compressing force exerted by the stomach wall.According to one embodiment, the implantable movement restriction device further comprises a third part, and the lower portion of the second part comprises a third connecting portion and the upper portion of the third part comprises a fourth connecting portion, such that the first, second and third parts can be connected for forming the implantable medical device.According to one embodiment, the second part is configured to exert a supporting or compressing force on the first part derived from a supporting or compressing force exerted by the third part on the second part. The third part may be configured to exert a supporting or compressing force on the second part derived from a supporting or compressing force exerted by the stomach wall on the third part.According to one embodiment, the apparatus further comprises a second interconnecting part, and the third and fourth connecting portions are configured to be connected to the second interconnecting part, such that the first interconnecting part connects the first part to the second part and the second interconnecting part connects the third part to the fourth part.According to one embodiment, the first and second resilient connecting portions are supported or compressed by a supporting or compressing force exerted by the third part on the second part.According to one embodiment, the first part comprises a first sub-part and a second sub-part, the second part comprises a first sub-part and a second sub-part, and the third part comprises a first sub-part and a second sub-part. The first and second sub-parts of the first part are configured to remain connected to each other by a supporting or compressing force exerted by at least one of the second part and the stomach wall, the first and second sub-parts of the second part are configured to remain connected to each other by a supporting or compressing force exerted by at least one of the third part and the stomach wall, and the first and second sub-parts of the third part are configured to remain connected to each other by a supporting or compressing force exerted by the stomach wall.According to one embodiment, the first part comprises a first, a second and a third sub-part and / or the second part comprises a first, a second and a third sub-part, and / or the third part comprises a first, a second and a third sub-part.According to one embodiment, the first part comprises a first, second, third and fourth sub-part, and / or the second part comprises a first, second, third and fourth sub-part, and / or the third part comprises a first, second, third and fourth sub-part.According to one embodiment, the movement restriction device is elongated and the first length is more than 2 times the second length, preferably more than 2,5 times the second length and even more preferably more than 3 times the second length.According to one embodiment, the implantable movement restriction device comprises at least one circular cross-section.The implantable movement restriction device may comprise a first, second and third cross-section in planes spaced apart and parallel to each other, wherein the first and third cross-sections have the same area, and the second cross-section is located between the first and third cross-section and have a smaller area. According to one embodiment, the implantable movement restriction device further comprises a fourth and fifth cross-section in planes spaced apart and parallel to the planes of the first, second and third cross-sections, wherein the third and fifth cross-sections have the same area, and the fourth cross-section is located between the third and fifth cross-sections and have a smaller area.According to one embodiment, the implantable movement restriction device may be configured to be fully invaginated. A first portion of the implantable movement restriction device may have a first volume enclosed by material of the implantable movement restriction device, and a second portion of the movement restriction device, separate from the first portion, may have a second volume enclosed by material of the implantable movement restriction device, The first volume and the second volumes are equally large and the first volume has a higher density than the second volume and the second volume has a density below 1000 kg / m3.According to one embodiment, the first volume comprises a first solid material, and the first solid material may comprise a polymer material, such as a silicone-based material or a polyurethane-based material. According to one embodiment, the second volume comprises a second solid material. The second solid material may comprise a polymer material, such as a polypropylene-based and a polyethylene-based material. In any one of the embodiments herein, the first volume may comprise a solid material having a density above 1000 kg / m3 and the second volume may comprise a solid material having a density below 1000 kg / m3.In any one of the embodiments herein, the second volume may comprises a fluid, which could be a liquid having a density a below 1000 kg / m3, such as an oil-based liquid or an alcohol-based liquid.In any one of the embodiments herein, the second volume may comprise a gas, and the second volume may comprise a plurality of volumes of gas enclosed by an enclosing material.According to one embodiment, the second volume may comprise a solid polymer material enclosing the enclosing material, and the enclosing material may be harder than the solid polymer material. According to one embodiment, the plurality of volumes of gas enclosed by an enclosing material makes up at least 10 volume percent of the second volume, more preferably at least 20 volume percent of the second volume, and even more preferably at least 30 volume percent of the second volume.The enclosing material may comprise glass. According to one embodiment, the movement restriction device has an average density below 1100 kg / m3, or an average density below 1050 kg / m3, or an average density below 1000 kg / m3.According to one embodiment, the movement restriction device comprises a first cross-sectional distance and a second cross-sectional distance. The implantable movement restriction device may be adjustable in situ, such that the shape of the implantable movement restriction device can be adjusted by the adjustment of the length of the first cross-sectional distance, such that the length of the first cross-sectional distance can be increased relative to the length of the second cross-sectional distance.According to one embodiment, the shape of the implantable movement restriction device can be adjusted by an increase of the length of the first cross-sectional distance relative to the length of the second cross-sectional distance while the length of a circumference of a cross-section of the implantable movement restriction device, in a plane parallel to the coronal plane of the patient remains constant.The first part may in any of the embodiments herein comprise an upper portion configured to, directly or indirectly, engage the thoracic diaphragm of the patient, and the upper portion may comprise at least one curvature. An apparatus for treating reflux disease of a human patient is further provided. The apparatus comprises an implantable movement restriction device configured to be at least partly invaginated by the stomach wall of the patient for restricting the movement of the cardia of the patient towards the thoracic diaphragm. The implantable movement restriction device comprising sensor configured to sense at least one of a force and a pressure, for monitoring a pressure or force exerted by the implantable movement restriction device on the stomach wall of the patient.According to one embodiment, the sensor is fixated to a surface of the implantable movement restriction device and / or integrated in the implantable movement restriction device. The sensor could comprise a strain gauge-based sensor, such as a piezoresistive or piezoelectric strain gauge-based sensor or an optical strain gauge-based sensor. In the alternative, the sensor could comprise a capacitive sensor or an electromagnetic sensor.According to one embodiment, the implantable movement restriction device comprises at least one enclosed chamber comprising a fluid, and the sensor is configured the sense a pressure in the fluid. The apparatus may further comprise at least one conduit and a sensor unit configured to house the sensor, and the conduit could be in fluid connection with the enclosed chamber of the implantable movement restriction device and with the sensor unit, such that the sensor can sense the pressure in the fluid in the enclosed chamber of the implantable movement restriction device through the fluid connection provided by the conduit. According to one embodiment, the apparatus further comprises an implantable energy source for powering the sensor and an implantable controller connected to the sensor. The implantable controller may comprise a wireless transceiver configured to receive a sensor signal from the sensor and transmit a wireless signal derived from the sensor signal to a unit external to the body of the patient. According to one embodiment, the implantable movement restriction device has a size such that the implantable movement restriction device can be fully invaginated by the fundus wall of the patient.The apparatus may further comprise at least one lead connected to the sensor, and the lead may be configured to connect the sensor to an external device configured to remain outside the patient’s body. The apparatus may further comprise a connector for detachably connecting the sensor to the lead, such that the lead can be disconnected from the sensor. In alternative embodiments, the sensor may be detachably attached to the implantable movement restriction device, such that the sensor can be detached from the implantable movement restriction device by pulling on the lead and the sensor may be detachably attached to the implantable movement restriction device using an adhesive.The implantable movement restriction device may in any of the embodiments herein have a size of less than 200cm2, preferably less than 100cm2, and more preferably less than 50cm2.According to one embodiment, the movement restriction device is elongated, and a first cross-sectional distance has a first length, and a second cross-sectional distance has a second length. The first length is more than 1,2 times the second length, preferably more than 1,5 times the second length and even more preferably more than 2 times the second length.According to one embodiment, the implantable movement restriction device comprises at least one circular cross-section.According to one embodiment, the implantable movement restriction device comprises a first, second and third cross-section in planes spaced apart and parallel to each other. The first and third cross-sections have the same area, and the second cross-section is located between the first and third cross-section and have a smaller area.According to one embodiment, the implantable movement restriction device comprises at least two parts, or at least three parts, or at least 4 parts.According to one embodiment, the at least two parts are configured to be assembled to form the implantable movement restriction device and the at least two parts may be configured to be connected to each other to form the implantable movement restriction device.According to one embodiment, the movement restriction device comprises a curved cross-section in a plane parallel to the transverse plane of the patient, and the curve is configured to partially enclose the esophagus of the patient.According to one embodiment, the movement restriction device comprises a curved cross-section in a plane parallel to the transverse plane of the patient. The curve may be configured to partially enclose the esophagus of the patient. According to one embodiment, the movement restriction device is configured to encircle at least 1 / 3 of the esophagus in a plane parallel to the transverse plane of the patient, in another embodiment, the movement restriction device is configured to encircle at least 1 / 2 of the esophagus in a plane parallel to the transverse plane of the patient, in another embodiment, the movement restriction device comprises a C-shaped cross-section in a plane parallel to the transverse plane of the patient, and the C-shaped cross-section is configured to partially enclose the esophagus of the patient, in another embodiment, the movement restriction device is configured to encircle at least 2 / 3 of the esophagus in a plane parallel to the transverse plane of the patient.According to one embodiment, a cross-section of the movement restriction device in a plane parallel to the transverse plane of the patient comprises a closed curve configured to enclose the esophagus of the patient. The implantable movement restriction device may in any of the embodiments comprise at least one circular cross-section.A surgical instrument for assisting in a surgical procedure for implanting an implantable movement restriction device is further provided. The movement restriction device is configured to be at least partly invaginated by the stomach wall of the patient for restricting the movement of the cardia of the patient towards the thoracic diaphragm. The surgical instrument comprises a handling portion configured to remain outside of the body of the patient in use, a distal portion configured to be inserted into the body of the patient, and a lead at least partially attached to the distal portion and configured to be connected to a sensor for sensing at least one of a force and a pressure, for monitoring a pressure or force exerted by the implantable movement restriction device on the stomach wall of the patient during implantation.According to one embodiment, the distal portion comprises a holding device connected to the handling portion and configured to be inserted into the body of the patient and to engage the movement restriction device.According to one embodiment, the holding device comprises an elongated portion configured to be inserted into the implantable movement restriction device.According to one embodiment, the holding device comprises a gripping portion configured to grip the implantable movement restriction device.The surgical instrument may be configured for placement of the implantable movement restriction device, and the surgical instrument further comprises a sleeve connected to the handling portion, and the holding device is configured to be partially placed within the sleeve and be displaceable in relation to the sleeve. The handling of the handling portion creates relative displacement of the holding device in relation to the sleeve, which disengages the holding device from the movement restriction device for performing the placement of the movement restriction device.According to one embodiment, the distal portion is bent in relation to the primary length axis of the surgical instrument, and the distal portion may be bent more than 20° in relation to the primary length axis of the instrument.According to one embodiment, the distal portion is flexible or bendable.According to one embodiment, the bending of the distal portion is controllable from the handling portion.According to one embodiment, the surgical instrument is an abdominal instrument configured to be inserted into the abdomen of the patent during an open surgical procedure. In the alternative, the surgical instrument is a laparoscopic instrument configured to be inserted into the abdomen of the patient through a trocar, and in yet another alternative, the surgical instrument is a gastroscopic instrument configured to be inserted into the body of the patient through the esophagus of the patient.According to one embodiment, the surgical instrument further comprises the sensor. The sensor may be configured to be detachably attached to the implantable movement restriction device, such that the sensor can be detached from the implantable movement restriction device and removed from the body of the patient during the surgical procedure. According to one embodiment, the sensor is configured to be attached to a surface of the implantable movement restriction device or attached in the implantable movement restriction device. The sensor may be configured to be detachably attached to the implantable movement restriction device using an adhesive. The surgical instrument may further comprise a connector for detachably connecting the sensor to the lead, such that the lead can be disconnected from the sensor. The sensor could comprise a strain gauge-based sensor, such as a piezoresistive or piezoelectric strain gauge-based sensor, or an optical strain gauge-based sensor, or a capacitive sensor, or an electromagnetic sensor.According to one embodiment, the implantable movement restriction device comprises at least one enclosed chamber comprising a fluid, and the sensor is a sensor configured the sense a pressure in a fluid.According to one embodiment, the surgical instrument further comprises an energy source for powering the sensor and a controller connected to the sensor. The controller may be an external device configured to remain on the outside of the patient when the surgical instrument is in use, and the controller is configured to receive a sensor signal from the sensor via the lead and provide an output on the basis the sensor signal. According to one embodiment, the controller comprises an output device configured to provide an output to a person, the output device comprises at least one unit selected from a list consisting of a unit providing audio output, a unit providing visual output, such as a lighting unit or a display unit, and a unit providing haptic output.An apparatus for treating reflux disease of a human patient is further provided, the apparatus comprising an elongated core having a length allowing the core to at least partly encircle the esophagus of the patient. The core comprises a first length variability function allowing the core to be arranged in a constricting state for hindering fluid from passing from the stomach 10 into the esophagus and in an expanded state for allowing food to pass into the stomach in response to the patient swallowing; and a second length variability function for post-operatively adjusting the length that the core has in its constricting state.According to one embodiment, the second length variability function comprises a hydraulic length variability function and may comprise at least one hydraulic chamber, and the length of the core can be post-operatively adjusted by injection of a fluid into, or withdrawal of a fluid from, the at least one hydraulic chamber. The hydraulic chamber may comprise at least one pleated portion, such as at least one bellows. According to one embodiment, the elongated core comprises a wall enclosing the hydraulic chamber, and the thickness of the wall varies affecting the alteration of the shape of the hydraulic chamber as fluid is injected into or withdrawn from the hydraulic chamber.According to one embodiment, the shape of the movement restriction device may be altered by the thinner portion of the wall enclosing the hydraulic adjustment chamber being deformed more than thicker portions of the wall enclosing the hydraulic adjustment chamber.According to one embodiment, the hydraulic chamber comprises at least one implantable injection port, or is connected to at least one implantable injection port.According to one embodiment, the second length variability function comprises a mechanical length variability function, and the mechanical length variability function may comprise a powered mechanical length variability function.According to one embodiment, the powered mechanical length variability function may comprise at least one of: an electrical motor, an electromagnet, and an electroactive material.According to one embodiment, the movement restriction device comprises a transferring element configured to transfer at least one of electrical energy, and mechanical force to the mechanical length variability function.According to one embodiment, the transferring element comprises at least one of: an electrical lead, a shaft for transferring rotating force, and a shaft for transferring linear force.The mechanical operation device may comprise a transmission configured to transform a rotating force generated by the electrical motor into a linear force for adjusting the length of the first cross-sectional distance.According to one embodiment, the first length variability function comprises a plurality of portions that are movable relative to each other.According to one embodiment, the first length variability function comprises an attractor for resiliently attracting adjacent portions of the elongated core to one another. The attractor may comprise an elastic element or may comprise at least two mutually attracting magnets.According to one embodiment, the apparatus further comprises a link connecting a first and a second one of said at least two magnets to each other.According to one embodiment, the elongated core is configured to exert an encircling pressure on the esophagus in the constricting state.According to one embodiment, the apparatus comprises two end portions configured to be coupled to each other to form a closed ring around the esophagus and the end portions may be configured to be releasably attached to each other and may comprise a respective interlockable attacher.According to one embodiment, the elongated core comprises a plurality of bodies configured to be arranged in an annular array around the esophagus.According to one embodiment, the elongated core further comprises a plurality of links, each of which extending between a respective pair of bodies arranged adjacent to each other.According to one embodiment, at least one of the plurality of bodies comprises the second length variability function for post-operatively adjusting the length of the core in its constricting state.According to one embodiment, at least one of the plurality of bodies comprises the hydraulic chamber for post-operatively adjusting the length of the core in its constricting state.The elongated core may have a size allowing at least a portion of the elongated core to protrude above the cardiac sphincter of the patient, when implanted, such that movement of the cardia towards the diaphragm is restricted to hinder the cardia from sliding through the diaphragm opening 32 into the patient’s thorax.According to one embodiment, the elongated core has a maximum height exceeding 2 cm, as measured in a normal direction to the plane in which the elongated core extends when encircling the esophagus. In alternative embodiments, the maximum height may be 3 cm or more, such as 4 cm or more, such as 5 cm or more.According to one embodiment, the elongated core is configured to be implanted such that a portion of the elongated core having the maximum height is arranged at the fundus side of the esophagus.According to one embodiment, the elongated core has a first cross-sectional distance and a second cross-sectional distance, and wherein the elongated core is configured to be implanted such that the first cross-sectional distance is more parallel than perpendicular to the cranial-caudal axis of the patient, and the second cross-sectional distance is more perpendicular than parallel to the cranial-caudal axis of the patient, and the elongated core is adjustable in situ, such that the shape of the elongated core can be adjusted by the adjustment of the length of the first cross-sectional distance, such that the length of the first cross-sectional distance can be increased relative to the length of the second cross-sectional distance.According to one embodiment, the shape of the elongated core can be adjusted by an increase of the length of the first cross-sectional distance relative to the length of the second cross-sectional distance while the length of a circumference of a cross-section of the elongated core, in a plane parallel to the coronal plane of the patient remains constant.According to one embodiment, the shape of a cross-section of the elongated core can be adjusted to an elongated shape by an increase of the length of the first cross-sectional distance relative to the length of the second cross-sectional distance.According to one embodiment, the elongated core comprises a lower portion configured to, directly or indirectly, engage the stomach of the patient in a region of the angle of his, such that the function of the elongated core is supported by tissue of the stomach in the region of the angle of his.According to one embodiment, the elongated core comprises an upper portion configured to, directly or indirectly, engage the thoracic diaphragm of the patient, and the upper portion comprises at least one curvature. The elongated core in any of the embodiments herein may be configured to be at least partially invaginated by the stomach wall.According to one embodiment, the elongated core is configured to be at least partially invaginated by the stomach wall of the fundus.According to one embodiment, the movement restriction device comprises a curved cross-section in a plane parallel to the transverse plane of the patient. The curve may be configured to partially enclose the esophagus of the patient. According to one embodiment, the movement restriction device is configured to encircle at least 1 / 3 of the esophagus in a plane parallel to the transverse plane of the patient, in another embodiment, the movement restriction device is configured to encircle at least 1 / 2 of the esophagus in a plane parallel to the transverse plane of the patient, in another embodiment, the movement restriction device comprises a C-shaped cross-section in a plane parallel to the transverse plane of the patient, and the C-shaped cross-section is configured to partially enclose the esophagus of the patient, in another embodiment, the movement restriction device is configured to encircle at least 2 / 3 of the esophagus in a plane parallel to the transverse plane of the patient.The second length variability function may in any of the embodiments herein be configured for post-operatively adjusting the length that the core has in its constricting state with more than 5%, or with more than 10%, or with more than 15% or with more than 20%.The apparatus may in any of the embodiments herein comprise at least one electrode for electrically stimulating at least one tissue portion of the patient. An apparatus for treating reflux disease of a human patient is further provided. The apparatus comprises an elongated core having a length allowing the elongated core to at least partly encircle the esophagus of the patient. The elongated core comprises a first length variability function allowing the core to be arranged in a constricting state for hindering fluid from passing from the stomach into the esophagus and in an expanded state for allowing food to pass into the stomach in response to the patient swallowing; and a protruding portion configured to protrude from the first length variability function in a direction more parallel than perpendicular to the cranial-caudal axis of the patient, in a substantially cranial direction, when the elongated core is implanted. The protruding portion is configured to protrude a distance of at least 10mm in a substantially cranial direction from a plane extending perpendicularly from the cranial-caudal axis of the patient and comprising the center of gravity of the elongated core, and the protruding portion is configured to directly or indirectly engage the thoracic diaphragm of the patient for restricting the movement of the cardia of the patient.The protruding portion may protrude a distance of at least 20mm in a substantially cranial direction from a plane extending perpendicularly from the cranial-caudal axis of the patient and comprising the center of gravity of the elongated core.The protruding portion may be configured to protrude in a substantially cranial direction from a plane extending perpendicularly from the cranial-caudal axis of the patient and comprising the center of gravity of the elongated core, a distance such that an upper portion of the protruding portion is placed at least 5mm above the cardiac sphincter. The protruding portion may be configured to protrude in a substantially cranial direction from a plane extending perpendicularly from the cranial-caudal axis of the patient and comprising the center of gravity of the elongated core, a distance such that an upper portion of the protruding portion is placed at least 10mm above the cardiac sphincter. The protruding portion may be configured to protrude in a substantially cranial direction from a plane extending perpendicularly from the cranial-caudal axis of the patient and comprising the center of gravity of the elongated core, a distance such that an upper portion of the protruding portion is placed at least 15mm above the cardiac sphincter. The elongated core may have a first cross-sectional area in a first plane extending perpendicularly from the cranial-caudal axis of the patient, and the protruding portion may have a second cross-sectional area in a second plane parallel to the first plane, and the first cross-sectional area may be more than 1,5 times the size of the second cross-sectional area. According to one embodiment, the second cross-sectional area is an average cross-sectional area of the protruding portion.According to one embodiment, the protruding portion has a third cross-sectional area in a third plane parallel to the first plane, and the second plane is positioned between the first and third planes, and the third cross-sectional area is more than 1,5 times the size of the second cross-sectional area. According to one embodiment, the apparatus further comprises a second elongated core having a length allowing the second elongated core to at least partly encircle the esophagus of the patient. The protruding portion may connect the first elongated core to the second elongated core. According to one embodiment, the elongated core comprises a lower portion configured to, directly or indirectly, engage the stomach of the patient in a region of the angle of his, such that the function of the elongated core is supported by tissue of the stomach in the region of the angle of his.According to one embodiment, the protruding portion comprises an upper portion configured to, directly or indirectly, engage the thoracic diaphragm of the patient, and the upper portion comprises at least one curvature. According to one embodiment, at least one of the first elongated core, the second elongate core and the protruding portion may be configured to be at least partially invaginated by the stomach wall.According to one embodiment, the protruding portion is adjustable in situ, such that the length that the protruding portion protrudes from the plane extending perpendicularly from the cranial-caudal axis of the patient and comprising the center of gravity of the elongated core can be adjusted. The protruding portion may be hydraulically adjustable and may further comprises a conduit configured to connect the hydraulically adjustable protruding portion to an implantable injection port.According to one embodiment, at least one of the protruding portion and the elongated core comprises an injection port, such that the hydraulically adjustable protruding portion can be adjusted by the injection or withdrawal of a hydraulic fluid into the injection port.According to one embodiment, the protruding portion comprises a bellows, and injection or withdrawal of a hydraulic fluid into the injection port adjusts a length of the bellows. According to one embodiment, the protruding portion comprises a wall enclosing a hydraulic adjustment chamber, and the thickness of the wall varies affecting the alteration of the shape of the protruding portion as fluid is injected into or withdrawn from the protruding portion. The shape of the protruding portion may be altered by the thinner portion of the wall enclosing the hydraulic adjustment chamber being deformed more than thicker portions of the wall enclosing the hydraulic adjustment chamber. According to one embodiment, the protruding portion is mechanically adjustable and the apparatus may comprise a mechanical operation device for mechanically adjusting the protruding portion. According to one embodiment, the movement restriction device comprises a transferring element configured to transfer at least one of: electrical energy, and mechanical force to the mechanically adjustable protruding portion.According to one embodiment, the transferring element comprises at least one of an electrical lead, a shaft for transferring rotating force, and a shaft for transferring linear force.The mechanical operation device may comprise an electrical motor, and may comprises a transmission configured to transform a rotating force generated by the electrical motor into a linear force for adjusting the length of the protruding portion.A portion of the protruding portion comprises a bellows, and wherein the operation of the mechanical operation device adjusts a length of the bellows. According to one embodiment, the protruding portion is electrically adjustable, and the apparatus may comprise at least one material configured to alter shape when exposed to an electrical current or an electrical voltage. The material may be at least one electroactive polymer, which could be at least one electroactive polymer selected from a list consisting of: ferroelectric polymers, electrostrictive graft polymers, electrostrictive paper, piezoelectric polymers and liquid crystal elastomers. In any of the embodiments herein, the length of the protruding portion may be adjustable in situ more than 1,2 times, or more than 1,3 times, or more than 1,5 times.According to one embodiment, the elongated core comprises a curved cross-section in a plane parallel to the transverse plane of the patient, and wherein the curve is configured to partially enclose the esophagus of the patient.According to one embodiment, the movement restriction device comprises a curved cross-section in a plane parallel to the transverse plane of the patient. The curve may be configured to partially enclose the esophagus of the patient. According to one embodiment, the movement restriction device is configured to encircle at least 1 / 3 of the esophagus in a plane parallel to the transverse plane of the patient, in another embodiment, the movement restriction device is configured to encircle at least 1 / 2 of the esophagus in a plane parallel to the transverse plane of the patient, in another embodiment, the movement restriction device comprises a C-shaped cross-section in a plane parallel to the transverse plane of the patient, and the C-shaped cross-section is configured to partially enclose the esophagus of the patient, in another embodiment, the movement restriction device is configured to encircle at least 2 / 3 of the esophagus in a plane parallel to the transverse plane of the patient.According to one embodiment, a cross-section of the elongated core in a plane parallel to the transverse plane of the patient may comprise a closed curve configured to enclose the esophagus of the patient. According to one embodiment, the first length variability function comprises an attractor for resiliently attracting adjacent portions of the elongated core to one another. The attractor may comprise an elastic element or at least two mutually attracting magnets. The apparatus may further comprise a link connecting a first and a second one of said at least two magnets to each other.According to one embodiment, the elongated core is configured to exert an encircling pressure on the esophagus in the constricting state.According to one embodiment, the apparatus comprises two end portions configured to be coupled to each other to form a closed ring around the esophagus. The end portions may be configured to be releasably attached to each other and may comprise a respective interlockable attacher.The elongated core may comprise a plurality of bodies configured to be arranged in an annular array around the esophagus.According to one embodiment, the elongated core further comprises a plurality of links, each of which extending between a respective pair of bodies arranged adjacent to each other.According to one embodiment, the elongated core is configured to be implanted such that the protruding portion is arranged at the fundus side of the esophagus.The apparatus may further comprise a second length variability function configured for post-operatively adjusting the length that the elongated core has in its constricting state with more than 5%, or with more than 10%, or with more than 15% or with more than 20%.The apparatus may in any of the embodiments herein comprise at least one electrode for electrically stimulating at least one tissue portion of the patient. A method for treating reflux disease of a human patient by implanting a movement restriction device is further provided. The movement restriction device is arranged to restrict movement of the cardia of the patient’s stomach towards the diaphragm to hinder the cardia from sliding through the diaphragm opening into the patient’s thorax. The movement restriction device comprises a curved inner surface configured to face the curved outer surface of the esophagus. The method comprising positioning and fixating the movement restriction device such that the curved inner surface encircles at least 1 / 3 of the esophagus in a plane extending perpendicular to the cranial – caudal axis, and the center of mass of the movement restriction device is placed in a plane extending perpendicular to the cranial – caudal axis, and wherein the shortest distance from a point on the plane to the angle of His exceeds 20mm.According to one embodiment, the method comprises the step of attaching the fundus of the stomach of the patient to the esophagus of the patient in a first position below the center of mass of the movement restriction device, such that the movement restriction device is supported by the attachment of the fundus to the esophagus.The step of attaching the fundus of the stomach of the patient to the esophagus of the patient in a first position may comprise attaching the fundus of the stomach of the patient to the esophagus of the patient at a distance from the angle of His exceeding 5mm.According to one embodiment, the step of positioning and fixating the movement restriction device comprises positioning and fixating the movement restriction device such that the upper most point of the movement restriction device is placed in a second plane extending perpendicular to the cranial – caudal axis, and the shortest distance from a point on the second plane to the angle of His exceeds 40mm.According to one embodiment, the step of positioning and fixating the movement restriction device comprises positioning and fixating the movement restriction device such that the upper most point of the movement restriction device is placed in a second plane extending perpendicular to the cranial – caudal axis, and wherein the shortest distance from a point on the second plane to the angle of His exceeds 50mm.According to one embodiment, the step of positioning and fixating the movement restriction device comprises positioning and fixating the movement restriction device such that the lower most point of the movement restriction device is placed in a third plane extending perpendicular to the cranial – caudal axis, and wherein the shortest distance from a point on the third plane to the angle of His exceeds 10mm.According to one embodiment, the step of positioning and fixating the movement restriction device comprises positioning and fixating the movement restriction device such that the lower most point of the movement restriction device is placed in a third plane extending perpendicular to the cranial – caudal axis, and wherein the shortest distance from a point on the third plane to the angle of His exceeds 20mm.According to one embodiment, the step of positioning and fixating the movement restriction device comprises positioning and fixating the movement restriction device such that the upper most point of the movement restriction device is placed in a second plane extending perpendicular to the cranial – caudal axis, and wherein the shortest distance from a point on the second plane to an upper-most point of the cardia exceeds 5mm.According to one embodiment, the step of positioning and fixating the movement restriction device comprises positioning and fixating the movement restriction device such that the upper most point of the movement restriction device is placed in a second plane extending perpendicular to the cranial – caudal axis, and wherein the shortest distance from a point on the second plane to an upper-most point of the cardia exceeds 10mm.According to one embodiment, the step of positioning and fixating the movement restriction device comprises positioning the center of mass of the movement restriction device in the second plane extending perpendicular to the cranial – caudal direction, and wherein the shortest distance from a point on the second plane to an upper-most point of the cardia exceeds 5mm.According to one embodiment, the step of positioning and fixating the movement restriction device comprises positioning the center of mass of the movement restriction device in the second plane extending perpendicular to the cranial – caudal direction, and wherein the shortest distance from a point on the second plane to an upper-most point of the cardia exceeds 10mm.According to one embodiment, the step of positioning and fixating the movement restriction device comprises positioning a movement restriction device encircling at least 1 / 2 of the esophagus in a plane extending perpendicular to the cranial – caudal direction.According to one embodiment, the step of positioning and fixating the movement restriction device comprises positioning a movement restriction device encircling at least 2 / 3 of the esophagus in a plane extending perpendicular to the cranial – caudal direction.According to one embodiment, the step of positioning and fixating the movement restriction device comprises positioning a movement restriction device encircling the esophagus in a plane extending perpendicular to the cranial – caudal direction.According to one embodiment, the curved inner surface configured to face the curved outer surface of the esophagus comprises a radius of curvature corresponding to or exceeding the radius of curvature of the esophagus, such that the curved inner surface comprises a radius of curvature corresponding to or exceeding the radius of curvature of the esophagus.According to one embodiment, the step of positioning and fixating the movement restriction device comprises positioning a movement restriction device comprising an electrode arrangement configured to electrically stimulate muscle tissue of the portion of the fundus and / or the serosa to improve the conditions for long term implantation of the movement restriction device.According to one embodiment, the method further comprises implanting an implantable energy source configured to provide the electrode with electrical power.According to one embodiment, the step of positioning and fixating the movement restriction device comprises positioning a movement restriction device having a constricting state for hindering fluid from passing from the stomach into the esophagus and an expanded state for allowing food to pass into the stomach in response to the patient swallowing.According to one embodiment, the step of positioning the movement restriction device comprises positioning a movement restriction device configured to exert an encircling pressure on the esophagus in the constricting state.According to one embodiment, the step of positioning and fixating the movement restriction device comprises positioning a movement restriction device comprising at least one attractor for resiliently attracting adjacent portions of the movement restriction device to generate the encircling pressure.The attractor may comprise an elastic element or at least two mutually attracting magnets. The apparatus may further comprise a link connecting a first and a second one of said at least two magnets to each other.According to one embodiment, the step of positioning and fixating the movement restriction device comprises positioning and fixating a movement restriction device having an adjustable volume.According to further aspects, it is an object to reduce the risk of migration of the implantable movement restriction device disclosed herein. Migration of the movement restriction device is generally undesirable as it may decrease the effectiveness of the treatment of reflux disease in a human patient receiving the movement restriction device.According to one aspect, there is provided an apparatus for treating reflux disease of a human patient. The apparatus comprises an implantable movement restriction device configured to be at least partly invaginated by the stomach wall of the patient for restricting the movement of the cardia of the patient towards the thoracic diaphragm. The implantable movement restriction device is comprising a surface friction reducing coating covering at least a part of the surface of the implantable movement restriction device. The surface friction reducing coating is configured to reduce the friction between the implantable movement restriction device and the tissue of the stomach wall by which the implantable movement restriction device is at least partially invaginated. It has been realized that the application of a surface friction reducing coating covering at least a part of the surface of the implantable movement restriction device advantageously prevents or reduces the risk of migration of the implantable movement restriction device. When implanted, the surface friction reducing coating maximizes contact with surrounding tissue, and it provides lubrication for the movement restriction device.Typically, the surface friction reducing coating is covering at least 20%, such as at least 30%, such as at least 40%, such as at least 50%, such as at least 60%, such as at least 70%, such as at least 80%, such as at least 90%, such as at least 95% of the surface of the movement restriction device. According to one embodiment, the surface friction reducing coating is covering the entire surface of the movement restriction device. A higher degree of surface coverage is associated with a higher reduction of the risk of migration of the implantable movement restriction device.In preferred embodiments, the surface friction reducing coating is selected from natural polymers; polysaccharide coatings, oils, hydrogels, and lubricating jellies.In certain embodiments, the surface friction reducing coating comprises one or more natural polymers dissolved in water. Preferred natural polymers are selected from polysaccharides, such as native and modified celluloses, native and modified starches, xanthan gum, guar gum, carrageenan, alginate, pectin, and combinations thereof. A preferred polymer is methylcellulose, such as hydroxypropyl methylcellulose (HPMC) and carboxymethylcellulose. Another preferred polymer is ethylcellulose, such as hydroxyethylcellulose.An example of a useful hydrogel is a poly(propylene fumarate-co-ethylene glycol) hydrogel.In some embodiments, the surface friction reducing coating is selected from racine oil, mineral oil, glycerin, and polyethylene glycol (PEG). A preferred agent is PEG. It is further preferred to use PEG with larger size (> 5 kDa) as it remains in tissues for several days before being cleared.The surface friction reducing coating may furthermore comprise an active agent selected from bactericides, antibiotics, bacteriostatics, analgesics and anesthetics.Examples of bactericides and bacteriostatics which are useful in the surface friction reducing coating include antibiotics. Antibiotics are naturally occurring or synthetic substances that are used to kill or inhibit the growth of bacteria. Some examples of antibiotics include penicillin (e.g. penicillin and amoxicillin), cephalosporins (e.g. cephalexin and cefuroxime), macrolides (e.g. erythromycin and azithromycin), tetracyclines (e.g. tetracycline and doxycycline), quinolones (e.g. ciprofloxacin and levofloxacin), sulfonamides (e.g. sulfamethoxazole and trimethoprim), aminoglycosides (e.g. gentamicin and tobramycin). Other examples of bactericides and bacteriostatics which are useful in the surface friction reducing coating include bacteriophages.Examples of analgesics which are useful in the surface friction reducing coating include anti-inflammatory analgesics (e.g. acetaminophen, aspirin, COX inhibitors, nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen and naproxen) and opioids (e.g. codeine, fentanyl, hydrocodone, meperidine, methadone, naloxone, naltrexone and oxycodone).Examples of anesthetics which are useful in the surface friction reducing coating include local anesthetics which can be either ester- or amide-based. Examples of ester local anesthetics include procaine, amethocaine, cocaine, benzocaine, tetracaine. Examples of amide local anesthetics include lidocaine, prilocaine, bupivacaine, levobupivacaine, ropivacaine, mepivacaine, dibucaine and etidocaine. A preferred anesthetic is lidocaine, preferably in a concentration of 1-10 % (w / v), such as 1-5% (w / v), such as 1-3% (w / v), such as about 2% (w / v).In certain embodiments, the surface friction reducing coating provides antiseptic properties to the movement restriction device.The surface friction reducing coating may also contain pH-adjusting compounds, including weak acids, weak bases and buffers.In some embodiments, the surface friction reducing coating provides softening of adjacent tissues. This may further prevents or reduce the risk of migration of the implantable movement restriction device.In certain embodiments, the surface friction reducing coating is a viscous medium. A viscous coating composition is a type of liquid or semi-solid material that is used to create a protective layer or film on a surface. This type of coating is characterized by its thick, sticky consistency, which allows it to adhere to the surface and form a durable, long-lasting layer. There are many different types of viscous coating compositions available, each with its own unique properties and characteristics. It is preferred that the viscous medium is a viscous aqueous medium, such as a viscous aqueous liquid, such as a viscous aqueous solution. The viscous aqueous medium may be a viscoelastic medium. A preferred viscoelastic medium is a gel. The viscous medium may also be a viscous liquid.Viscosity can be e.g. determined at 20°C using a shear rate controlled rheometer (Model 302, Anton Paar, Germany), using a parallel plate geometry (plate diameter 50 mm, gap 100 μm). In this setup, the viscosity of water is approximately constant at 1 mPa·s, at shear rates between 0 - 100 s-1. For avoidance of doubt, viscous media as defined herein are considerably more viscous than water. Viscous media as defined herein typically exhibit a viscosity of at least 10 mPa·s, such as at least 50 mPa·s at shear rates between 0 - 100 s-1, such as at 50 s-1. Preferably, viscous media as defined herein exhibit a viscosity of at least 100 mPa·s, such as at least 200 mPa·s at shear rates between 0 - 100 s-1, such as at 50 s-1. The specific values above are relevant for this specific setup, but the skilled person can easily determine corresponding values for viscosity in other experimental setups. Typically, the surface friction reducing coating has a higher viscosity than water.The surface friction reducing coating may comprise preservatives. Examples of preservatives include antimicrobial preservatives, e.g. sorbic acid, parabens and lactic acid. A preferred type of preservatives is parabens, e.g. methylparaben and propylparaben.Preferably, the surface friction reducing coating is configured to remain in a pouch for housing the implantable movement restriction device for a time period exceeding 7 days, preferably exceeding 14 days, such as exceeding 21 days or 28 days.Specific examples of the surface friction reducing coating are:(1) Xylocaine jelly, containing 0.1 - 10% (w / v) xylocaine (lidocaine hydrochloride). The composition also contains methylparaben, propylparaben, hydroxypropyl methylcellulose, and sodium hydroxide and / or hydrochloric acid to adjust pH to 6.0–7.0.(2) Xylocaine viscous composition, containing 0.1 - 10% (w / v) xylocaine (lidocaine hydrochloride). The composition also contains carboxymethylcellulose sodium, methylparaben, propylparaben, purified water and saccharin sodium.(3) Surgical lubricant, containing hydroxypropyl methylcellulose, propylene glycol, chlorhexidine gluconate, and sterile water.(4) Poly(propylene fumarate-co-ethylene glycol) hydrogels(5) Polyethylene glycol (PEG) polymers, > 5 kDa(6) Lubricating glycerin jelly, containing water, PEG, glycerin, carbomer, sodium hydroxide, methylparaben, propylparaben.(7) Lidocaine jelly, , containing 0.1 - 10% (w / v) lidocaine hydrochloride. The composition also contains glycerol, hydrochloric acid, hydroxyethylcellulose, sodium hydroxide, and water.In some embodiments disclosed herein, the implantable movement restriction device has a size such that the implantable movement restriction device can be fully invaginated by the fundus wall of the patient as set out herein. Preferably, the implantable movement restriction device has a size of less than 200 cm2, preferably less than 100 cm2, and more preferably less than 50 cm2.In certain embodiments disclosed herein, the movement restriction device is elongated. A first cross-sectional distance has a first length, and a second cross-sectional distance has a second length, wherein the first length is more than 1,2 times the second length, preferably more than 1,5 times the second length and even more preferably more than 2 times the second length.In some embodiments disclosed herein, implantable movement restriction device (100) comprises at least one circular cross-section. In certain embodiments, the implantable movement restriction device (100) comprises a first, second and third cross-section in planes spaced apart and parallel to each other, wherein the first and third cross-sections have the same area, and the second cross-section is located between the first and third cross-section and have a smaller area.In certain embodiments disclosed herein, the implantable movement restriction device comprises at least two parts, or at least three parts, or at least 4 parts. Optionally, the at least two parts are configured to be assembled to form the implantable movement restriction device. Further optionally, the at least two parts are configured to be connected to each other to form the implantable movement restriction device.In some embodiments disclosed herein, the movement restriction device comprises a curved cross-section in a plane parallel to the transverse plane of the patient, and wherein the curve is configured to partially enclose the esophagus of the patient. Advantageously, the movement restriction device is configured to encircle at least 1 / 3 of the esophagus in a plane parallel to the transverse plane of the patient, and preferably at least 1 / 2 of the esophagus in a plane parallel to the transverse plane of the patient. In certain embodiments disclosed herein, the movement restriction device comprises a C-shaped cross-section in a plane parallel to the transverse plane of the patient, and wherein the C-shaped cross-section is configured to partially enclose the esophagus of the patient. Optionally, the movement restriction device is configured to encircle at least 2 / 3 of the esophagus in a plane parallel to the transverse plane of the patient. In specific embodiments, a cross-section of the movement restriction device in a plane parallel to the transverse plane of the patient comprises a closed curve configured to enclose the esophagus of the patient. In some embodiments disclosed herein, the implantable movement restriction device (100) comprises at least one circular cross-section.According to related aspects, there is also provided a method for treating reflux disease of a human patient by implanting a movement restriction device (100). The method comprises: at least partially invaginating the movement restriction device in the stomach of the patient such that the movement restriction device restricts movement of the cardia (22) of the patient’s stomach (10) towards the thoracic diaphragm (30) to hinder the cardia from sliding through the diaphragm opening (32) into the patient’s thorax, wherein the surface of the movement restriction device is at least partially covered by a surface friction reducing coating.There is furthermore provided a friction-reducing composition for use in the method as defined herein as a surface friction reducing coating. There is also provided a use of a composition selected from natural polymers, polysaccharide coatings, oils, hydrogels, and lubricating jellies as a surface friction reducing coating of at least part of the surface of an implantable movement restriction device for treating reflux disease of a human patient, wherein the movement restriction device (100) is configured to be at least partially invaginated by a stomach wall of a patient and arranged to restrict movement of the cardia (22) of a patient’s stomach (10) towards the diaphragm (30) to hinder the cardia from sliding through the diaphragm opening (32) into the patient’s thorax.When implanted, the surface friction reducing coating maximizes contact with surrounding tissue, and it provides lubrication for the movement restriction device.In certain embodiments, the method comprises the step of applying the surface friction reducing coating onto the movement restriction device prior to implantation in the body of the patient. This implies that the coating is applied ex vivo. In other embodiments, the method comprises the step applying the surface friction reducing coating in situ between the movement restriction device and tissue of the stomach wall of the patient. In some embodiments, the method comprises the steps of:- partially invaginating the movement restriction device in the stomach of the patient,- applying the surface friction reducing coating in situ between the movement restriction device and tissue of the stomach wall of the patient, and- further invaginating the movement restriction device in the stomach of the patient.Optionally, the step of at least partially invaginating the movement restriction device in the stomach of the patient comprises fully invaginating the movement restriction device in the stomach of the patient.In certain embodiments, the method is a laparoscopic surgical method, and the method further comprises the step of introducing the movement restriction device into the body of the patient through a laparoscopic trocar after the surface friction reducing coating has been applied. In other embodiments, the method is a laparoscopic surgical method, and the step of applying the surface friction reducing coating in situ between the movement restriction device and tissue of the stomach wall of the patient comprises applying the surface friction reducing coating in situ using a laparoscopic instrument inserted into the body of the patient though a laparoscopic trocar.In some embodiments, the method is a gastroscopic method, and the method further comprises the step of introducing the movement restriction device into the body of the patient through the esophagus of the patient after the surface friction reducing coating has been applied. In certain embodiments, the method is a gastroscopic method, and the step of applying the surface friction reducing coating in situ between the movement restriction device and tissue of the stomach wall of the patient comprises applying the surface friction reducing coating in situ using a gastroscopic instrument inserted into the body of the patient though the esophagus.Typically, the surface friction reducing coating is covering at least 20%, such as at least 30%, such as at least 40%, such as at least 50%, such as at least 60%, such as at least 70%, such as at least 80%, such as at least 90%, such as at least 95% of the surface of the movement restriction device. According to one embodiment, the surface friction reducing coating is covering the entire surface of the movement restriction device. A higher degree of surface coverage is associated with a higher reduction of the risk of migration of the implantable movement restriction device.In some embodiments, the step of at least partially invaginating a movement restriction device comprises at least partially invaginating a movement restriction device comprising a surface friction reducing coating covering the entire surface of the movement restriction device.In preferred embodiments, the step of at least partially invaginating a movement restriction device comprises at least partially invaginating a movement restriction device comprising a surface friction reducing coating selected from natural polymers, polysaccharide coatings, oils, hydrogels, and lubricating jellies.In certain embodiments, the surface friction reducing coating comprises one or more natural polymers dissolved in water. Preferred natural polymers are selected from polysaccharides, such as native and modified celluloses, native and modified starches, xanthan gum, guar gum, carrageenan, alginate, pectin, and combinations thereof. A preferred polymer is methylcellulose, such as hydroxypropyl methylcellulose (HPMC) and carboxymethylcellulose. Another preferred polymer is ethylcellulose, such as hydroxyethylcellulose.An example of a useful hydrogel is a poly(propylene fumarate-co-ethylene glycol) hydrogel.In some embodiments, the surface friction reducing coating is selected from racine oil, mineral oil, glycerin, and polyethylene glycol (PEG). A preferred agent is PEG. It is further preferred to use PEG with larger size (> 5 kDa) as it remains in tissues for several days before being cleared.The surface friction reducing coating may furthermore comprise an active agent selected from bactericides, antibiotics, bacteriostatics, analgesics and anesthetics.Examples of bactericides and bacteriostatics which are useful in the surface friction reducing coating include antibiotics. Antibiotics are naturally occurring or synthetic substances that are used to kill or inhibit the growth of bacteria. Some examples of antibiotics include penicillin (e.g. penicillin and amoxicillin), cephalosporins (e.g. cephalexin and cefuroxime), macrolides (e.g. erythromycin and azithromycin), tetracyclines (e.g. tetracycline and doxycycline), quinolones (e.g. ciprofloxacin and levofloxacin), sulfonamides (e.g. sulfamethoxazole and trimethoprim), aminoglycosides (e.g. gentamicin and tobramycin). Other examples of bactericides and bacteriostatics which are useful in the surface friction reducing coating include bacteriophages.Examples of analgesics which are useful in the surface friction reducing coating include anti-inflammatory analgesics (e.g. acetaminophen, aspirin, COX inhibitors, nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen and naproxen) and opioids (e.g. codeine, fentanyl, hydrocodone, meperidine, methadone, naloxone, naltrexone and oxycodone).Examples of anesthetics which are useful in the surface friction reducing coating include local anesthetics which can be either ester- or amide-based. Examples of ester local anesthetics include procaine, amethocaine, cocaine, benzocaine, tetracaine. Examples of amide local anesthetics include lidocaine, prilocaine, bupivacaine, levobupivacaine, ropivacaine, mepivacaine, dibucaine and etidocaine. A preferred anesthetic is lidocaine, preferably in a concentration of 1-10 % (w / v), such as 1-5% (w / v), such as 1-3% (w / v), such as about 2% (w / v).In certain embodiments, the surface friction reducing coating provides antiseptic properties to the movement restriction device.The surface friction reducing coating may also contain pH-adjusting compounds, including weak acids, weak bases and buffers.In some embodiments, the surface friction reducing coating provides softening of adjacent tissues. This may further prevents or reduce the risk of migration of the implantable movement restriction device.In certain embodiments, the surface friction reducing coating is a viscous medium. A viscous coating composition is a type of liquid or semi-solid material that is used to create a protective layer or film on a surface. This type of coating is characterized by its thick, sticky consistency, which allows it to adhere to the surface and form a durable, long-lasting layer. There are many different types of viscous coating compositions available, each with its own unique properties and characteristics. It is preferred that the viscous medium is a viscous aqueous medium, such as a viscous aqueous liquid, such as a viscous aqueous solution. The viscous aqueous medium may be a viscoelastic medium. A preferred viscoelastic medium is a gel. The viscous medium may also be a viscous liquid.Viscosity can be e.g. determined at 20°C using a shear rate controlled rheometer (Model 302, Anton Paar, Germany), using a parallel plate geometry (plate diameter 50 mm, gap 100 μm). In this setup, the viscosity of water is approximately constant at 1 mPa·s, at shear rates between 0 - 100 s-1. For avoidance of doubt, viscous media as defined herein are considerably more viscous than water. Viscous media as defined herein typically exhibit a viscosity of at least 10 mPa·s, such as at least 50 mPa·s at shear rates between 0 - 100 s-1, such as at 50 s-1. Preferably, viscous media as defined herein exhibit a viscosity of at least 100 mPa·s, such as at least 200 mPa·s at shear rates between 0 - 100 s-1, such as at 50 s-1. The specific values above are relevant for this specific setup, but the skilled person can easily determine corresponding values for viscosity in other experimental setups. Typically, the surface friction reducing coating has a higher viscosity than water.The surface friction reducing coating may comprise preservatives. Examples of preservatives include antimicrobial preservatives, e.g. sorbic acid, parabens and lactic acid. A preferred type of preservatives is parabens, e.g. methylparaben and propylparaben.Preferably, the surface friction reducing coating is configured to remain in a pouch for housing the implantable movement restriction device for a time period exceeding 7 days, preferably exceeding 14 days, such as exceeding 21 days or 28 days.Specific examples of the surface friction reducing coating are:(1) Xylocaine jelly, containing 0.1 - 10% (w / v) xylocaine (lidocaine hydrochloride). The composition also contains methylparaben, propylparaben, hydroxypropyl methylcellulose, and sodium hydroxide and / or hydrochloric acid to adjust pH to 6.0–7.0.(2) Xylocaine viscous composition, containing 0.1 - 10% (w / v) xylocaine (lidocaine hydrochloride). The composition also contains carboxymethylcellulose sodium, methylparaben, propylparaben, purified water and saccharin sodium.(3) Surgical lubricant, containing hydroxypropyl methylcellulose, propylene glycol, chlorhexidine gluconate, and sterile water.(4) Poly(propylene fumarate-co-ethylene glycol) hydrogels(5) Polyethylene glycol (PEG) polymers, > 5 kDa(6) Lubricating glycerin jelly, containing water, PEG, glycerin, carbomer, sodium hydroxide, methylparaben, propylparaben.(7) Lidocaine jelly, , containing 0.1 - 10% (w / v) lidocaine hydrochloride. The composition also contains glycerol, hydrochloric acid, hydroxyethylcellulose, sodium hydroxide, and water.In some embodiments disclosed herein, the implantable movement restriction device has a size such that the implantable movement restriction device can be fully invaginated by the fundus wall of the patient as set out herein. Preferably, the implantable movement restriction device has a size of less than 200 cm2, preferably less than 100 cm2, and more preferably less than 50 cm2. The step of at least partially invaginating a movement restriction device may comprise at least partially invaginating a movement restriction device having a size such that the implantable movement restriction device can be fully invaginated by the fundus wall of the patient. Preferably, the step of at least partially invaginating a movement restriction device comprises at least partially invaginating a movement restriction device having a size of less than 200 cm2, preferably less than 100 cm2, and more preferably less than 50 cm2.In some embodiments, the step of at least partially invaginating a movement restriction device comprises at least partially invaginating a movement restriction device being elongated and having a first cross-sectional distance having a first length, and a second cross-sectional distance having a second length, and wherein the first length is more than 1,2 times the second length, preferably more than 1,5 times the second length and even more preferably more than 2 times the second length.In certain embodiments, the step of at least partially invaginating a movement restriction device comprises at least partially invaginating a movement restriction device comprising at least one circular cross-section.In some embodiments, the step of at least partially invaginating a movement restriction device comprises at least partially invaginating a movement restriction device comprising a first, second and third cross-section in planes spaced apart and parallel to each other, wherein the first and third cross-sections have the same area, and the second cross-section is located between the first and third cross-section and have a smaller area.In certain embodiments, the step of at least partially invaginating a movement restriction device comprises at least partially invaginating a movement restriction device comprising at least two parts, or at least three parts, or at least 4 parts. Preferably, the step of at least partially invaginating a movement restriction device comprises assembling at least two parts for forming the implantable movement restriction device. In some embodiments, the step of at least partially invaginating a movement restriction device comprises at least partially invaginating a movement restriction device comprising a curved cross-section in a plane parallel to the transverse plane of the patient, and wherein the curve is configured to partially enclose the esophagus of the patient.In certain embodiments, the step of at least partially invaginating a movement restriction device comprises at least partially invaginating a movement restriction device comprising at least one circular cross-section.According to an aspect, an apparatus for treating reflux disease of a human patient is provided, comprising an implantable movement restriction device and an electrode arrangement. The implantable movement restriction device has a shape and size that allows it to be arranged to rest against a fundus wall portion of the patient’s stomach and to be at least partly invaginated by the fundus wall portion, such that the movement restriction device is implanted at a position between the patient’s diaphragm and a lower portion of the fundus wall, and such that movement of the cardia of the patient’s stomach towards the diaphragm is restricted to hinder the cardia from sliding through the diaphragm opening into the patient’s thorax. The electrode arrangement is configured to be arranged between the movement restriction device and the fundus wall portion and to engage and electrically stimulate muscle tissue of the fundus wall portion to exercise the muscle tissue to improve the conditions for long term implantation of the movement restriction device.According to an aspect, an apparatus for treating reflux disease of a human patient is provided, comprising an at least partly ring-shaped implantable movement restriction device and an electrode arrangement. The implantable movement restriction device comprises a first portion configured to be at least partly invaginated by a first wall portion of the patient’s stomach and arranged such that at least a part of the first portion is arranged above the cardiac notch of the patient’s stomach, and such that movement of the cardia towards the diaphragm is restricted to prevent the cardia from sliding through the diaphragm opening into the patient’s thorax. The electrode arrangement is configured to be arranged between the movement restriction device and the first wall portion and to electrically stimulate muscle tissue of the first wall portion to exercise the muscle tissue to improve the conditions for long term implantation of the movement restriction device.According to an aspect, an apparatus for treating reflux disease of a human patient is provided, comprising an elongated core and a tubular cover. The elongated core has a length allowing the core to at least partly encircle the esophagus of the patient, wherein the length is variable to allow the core to be arranged in a constricting state for hindering fluid from passing from the stomach into the esophagus and in an expanded state for allowing food to pass into the stomach in response to the patient swallowing. The tubular cover is configured to encloses at least a part of the core and comprises a plurality of portions adapted to bend relative to each other to allow the core to change between the constricting state and the expanded state, when the cover is at least partly covered by fibrotic tissue, without being substantially hindered or impeded by the presence of said fibrotic tissue.According to an aspect, an apparatus for treating reflux disease of a human patient is provided, comprising an elongated core having a length allowing the core to at least partly encircle the esophagus of the patient, wherein the length is variable to allow the core to be arranged in a constricting state for hindering fluid from passing from the stomach into the esophagus and in an expanded state for allowing food to pass into the stomach in response to the patient swallowing. The apparatus further comprises an electrode arrangement comprising an electrode element supported by the core and configured to be arranged between the apparatus and the esophagus and to electrically stimulate muscle tissue of the esophagus.According to an aspect, an apparatus for treating reflux disease of a human patient, is provided comprising a tubular device having a length allowing the tubular device to at least partly encircle the esophagus of the patient, wherein the length is variable to allow the tubular cover to be arranged in a constricting state for hindering fluid from passing from the stomach into the esophagus and in an expanded state for allowing food to pass into the stomach in response to the patient swallowing. The outer surface of the tubular device may comprise a plurality of portions adapted to bend relative to each other to allow the tubular device to change between the constricting state and the expanded state, when the outer surface is at least partly covered by fibrotic tissue, without being substantially hindered or impeded by the presence of said fibrotic tissue.According to an aspect, an apparatus for treating reflux disease of a human patient is provided, comprising an elongated core having a length allowing the core to at least partly encircle the esophagus of the patient. The length may be variable to allow the core to be arranged in a constricting state for hindering fluid from passing from the stomach into the esophagus and in an expanded state for allowing food to pass into the stomach in response to the patient swallowing. Further, the elongated core has a size allowing at least a portion of the elongated core to protrude above the cardiac sphincter of the patient, when implanted, such that movement of the cardia towards the diaphragm is restricted to hinder the cardia from sliding through the diaphragm opening into the patient’s thorax.According to an aspect, an apparatus for treating reflux disease of a human patient is provided, which is adapted to at least partly encircle the esophagus (20) of the patient. The apparatus comprises a first implantable portion and a second implantable portion, wherein the first implantable portion has a shape and size allowing it to be arranged to rest against a fundus wall portion of the patient’s stomach and to be at least partly invaginated by the fundus wall portion, such that the first implantable portion is implanted at a position between the patient’s diaphragm and a lower portion of the fundus wall, and such that movement of the cardia of the patient’s stomach towards the diaphragm is restricted to hinder the cardia from sliding through the diaphragm opening into the patient’s thorax. The second implantable portion is elongated to at least partly encircle the esophagus and has a variable length for allowing the apparatus be arranged in a constricting state for hindering fluid from passing from the stomach into the esophagus and in an expanded state for allowing food to pass into the stomach in response to the patient swallowing.According to an aspect, an apparatus for treating reflux disease of a human patient is provided, which is adapted to at least partly encircle the esophagus of the patient. The apparatus comprises a movement restriction device, an elongated support device and an electrode arrangement. The movement restriction device has a shape and size allowing it to be arranged to rest against a fundus wall portion of the patient’s stomach and to be at least partly invaginated by the fundus wall portion, such that the first implantable portion is implanted at a position between the patient’s diaphragm and a lower portion of the fundus wall, and such that movement of the cardia of the patient’s stomach towards the diaphragm is restricted to hinder the cardia from sliding through the diaphragm opening into the patient’s thorax. The elongated support device is connected to the movement restriction device and configured to at least partly encircle the esophagus. The electrode arrangement comprises an electrode element supported by the support device and configured to electrically stimulate muscle tissue of the esophagus. Further, the support device comprises a rigidity that allows the position of the electrode element relative to the esophagus to be determined mainly by the position and orientation of the movement restriction device.According to an aspect, a method for treating reflux disease of a human patient is provided. The method involves implanting a movement restriction device such that the movement restriction device is arranged to restrict movement of the cardia of the patient’s stomach towards the diaphragm to hinder the cardia from sliding through the diaphragm opening into the patient’s thorax. The method comprises placing the movement restriction device such that a lower portion of the movement restriction device rests against the serosa at the angle of His, and such that an upper portion of the movement restriction device defines a gap between the movement restriction device and the patient’s esophagus, when the lower portion rests against the angle of His. The method further comprises arranging a portion of the fundus of the stomach in the gap and attaching the fundus to the patient’s esophagus to at least partly enclose the movement restriction device by the portion of the fundus.According to an aspect, an apparatus for treating reflux disease of a human patient is provided, comprising an implantable movement restriction device and an elongated attacher configured to be attached to the movement restriction device and to be at least partly invaginated by a wall portion of the patient’s stomach. The attacher comprises a shape and size allowing it to be invaginated by the wall portion to hinder rotation of the movement restriction device. The attacher is further configured to be invaginated by the wall portion such that the movement restriction device is arranged at a position between the patient’s diaphragm and the wall portion, distant from the patient’s esophagus, to restrict movement of the cardia of the patient’s stomach towards the diaphragm to hinder the cardia from sliding through the diaphragm opening into the patient’s thorax.According to an aspect, an apparatus for treating reflux disease of a human patient, comprising an at least partly ring-shaped implantable movement restriction device configured to be arranged such that at a first, lower portion of the movement restriction device is arranged at the cardia of the patient’s stomach and such that a second, upper portion of the movement restriction device is arranged to abut the diaphragm of the patient, such that movement of the cardia towards the diaphragm is restricted to prevent the cardia from sliding through the diaphragm opening into the patient’s thorax. The apparatus is further configured to be arranged to define a gap or spacing between the second, upper portion of the movement restriction device and the outside of the esophagus when the apparatus is implanted. The apparatus may be formed of the movement restriction device as disclosed herein, or at least comprise such a movement restriction device.According to an aspect, a method of treating reflux disease in a human patient is provided, involving implanting an apparatus comprising a movement restriction device and an elongated support device, such that the support device at least partly encircles the esophagus of the patient and such that the movement restriction device is at arranged on the fundus side of the esophagus to restrict the movement of the cardia in relation to the diaphragm to hinder the cardia to from sliding through the diaphragm opening into the patient’s thorax. The method comprises the steps of introducing the apparatus into the abdominal cavity, placing the apparatus such that the movement restriction device rests against the outside of the stomach’s fundus, wrapping a portion of the fundus around at least a part of the movement restriction device, affixing the fundus to the esophagus such that the movement restriction device is arranged at a position between the diaphragm and the cardiac sphincter, and such that a part of the fundus is arranged between the movement restriction device and the esophagus and arranging the support device to at least partly encircle the esophagus. The movement restriction device and the second portion form a ring-shaped body extending through the pouch to at least partly encircle the esophagus.According to an aspect, a method for affixing a fundus portion of the stomach of a human patient to the patient’s esophagus is provided, wherein the fundus portion extends from the angle of His and in a direction away from the esophagus. The method comprises folding the fundus portion towards the esophagus such that the fundus portion rests against the esophagus, from the angle of His and upwards along the esophagus, and affixing the fundus portion to the esophagus by means of fasteners arranged along a first line and a second line. The first line and the second line extend along the esophagus and are arranged such that a distance between the first line and the second line increases with an increasing distance from the angle of His.According to an aspect, an apparatus for treating reflux disease in a human patient according to any of the above aspects is provided. The apparatus comprises an electrode arrangement for electrically stimulating the patient’s muscle tissue to exercise the muscle tissue to improve the conditions for long term implantation of the apparatus, as outlined above. The apparatus further comprises an implantable energy source configured to provide the electrode arrangement with electrical power, a controller operably connected to the electrode arrangement for controlling the electrical stimulation of the muscle tissue.According to an aspect, an apparatus for treating reflux disease of a human patient according to any one of the above aspects is provided. The apparatus comprises an electrode arrangement, an implantable energy source configured to provide the apparatus with electrical power, an external energy source configured be arranged outside of the patient’s body and configured to provide energy to the implantable energy source, and an implantable charger configured to be electrically connected to the implantable energy source and enable charging of the implantable energy source by the external energy source.According to an aspect, there is provided an apparatus for treating reflux disease of a human patient, comprising: an implantable movement restriction device having a shape and size allowing it to be arranged to rest against a fundus wall portion of the patient’s stomach (10), such that the movement restriction device is implanted at a position between the patient’s diaphragm (30) and a portion of the fundus wall, and such that movement of the cardia (22) of the patient’s stomach towards the diaphragm is restricted to hinder the cardia from sliding through the diaphragm opening into the patient’s thorax, wherein the implantable movement restriction device comprises an outer surface configured to rest against the stomach wall portion, and wherein an average surface roughness measured on the outer surface is no more than 0.5 µm.According to an aspect, there is provided an apparatus for treating reflux disease of a human patient, comprising: an implantable movement restriction device having a shape and size allowing it to be arranged to rest against a fundus wall portion of the patient’s stomach, such that the movement restriction device is implanted at a position between the patient’s diaphragm and a portion of the fundus wall, and such that movement of the cardia of the patient’s stomach towards the diaphragm is restricted to hinder the cardia from sliding through the diaphragm opening into the patient’s thorax, wherein the implantable movement restriction device comprises an outer surface configured to rest against the stomach wall portion, and wherein an indentation hardness on the Shore A scale measured on the outer surface is at least 50.According to an aspect, there is provided an apparatus for treating reflux disease of a human patient, comprising an implantable movement restriction device having a shape and size allowing it to be arranged to rest against a fundus wall portion of the patient’s stomach, such that the movement restriction device is implanted at a position between the patient’s diaphragm and a portion of the fundus wall, and such that movement of the cardia of the patient’s stomach towards the diaphragm is restricted to hinder the cardia from sliding through the diaphragm opening into the patient’s thorax, wherein the implantable movement restriction device comprises a plurality of segments, wherein the plurality of segments are comprised of a core part and a plurality of outer parts, and wherein the core part has an average density of above 1000 kg / m3According to an embodiment, an apparatus for treating reflux disease of a human patient according to any one of the above aspects is provided. The apparatus when comprises an electrode arrangement, and a controller configured to be operably connected to the electrode arrangement for controlling the electrical stimulation of the muscle tissue. The controller comprises an implantable communicator for transmitting and / or receiving a signal to / from the outside of the patient’s body.According to an embodiment of the above aspects, the electrode arrangement may be arranged on an outer surface of the movement restriction device.According to some embodiments of the above aspects, the electrode arrangements may comprise a plurality of electrode elements, wherein each of the electrode elements is configured to engage and electrically stimulate the muscle tissue. The electrode arrangement may further comprise a coiled wire for increasing a contact surface between the electrode arrangement and the muscle tissue and for allowing the electrode arrangement to follow contraction and relaxation of the muscle tissue.According to some embodiments of the above aspects, the electrode arrangement may comprise a bare electrode portion configured to form a metal-tissue interface with the muscle tissue so as to allow faradaic charge transfer to the be predominant charge transfer mechanism over the interface. Alternatively, or additionally the electrode arrangement may comprise an electrode portion that is at least partly covered by a dielectric material configured to form a dielectric-tissue interface with the muscle tissue so as to allowing a faradaic portion of the charge transfer mechanism over the interface to be reduced.According to some embodiments, the electrode arrangement may be configured to be arranged to electrically stimulate the cardiac sphincter to cause the cardiac sphincter to contract. The electrode arrangement may comprise at least two electrode elements configured to be arranged on opposing sides of the cardiac sphincter. Further, the apparatus may comprise a holder configured to support the at least two electrode elements at the opposing sides of the cardiac sphincter.Exemplary embodiments of a movement restriction device according to at least some of the above aspects will now be discussed. According to an embodiment, a volume of the movement restriction device may be non-adjustable after implantation. According to another embodiment, the volume of the movement restriction device may be adjustable after implantation. The volume may be adjustable invasively or non-invasively. In an example, the movement restriction device comprises an injection port for allowing a fluid to be injected or extracted from the inside of the movement restriction device so as to vary the volume of the movement restriction device after implantation.According to an embodiment, the movement restriction device may comprise a biocompatible outer surface configured to rest against the fundus wall portion.According to an embodiment, the movement restriction device may be substantially spherical or egg-shaped. In an example, the movement restriction device may have a portion configured to be arranged to point away from the esophagus when implanted. In a further example, a lower portion of the movement restriction device may be wider that an upper portion.According to an embodiment, the movement restriction device may be configured to be invaginated when placed on the outside of the fundus wall portion. In another embodiment, the movement restriction device may be configured to be invaginated when placed on the inside of the fundus wall portion.According to an embodiment, the movement restriction device may be configured to be introduced in the patient’s body by means of a gastroscope or an intraluminal instrument. The movement restriction device may for example be configured to change its shape to allow it to pass through a trocar during insertion into the patient’s body.According to an embodiment, the movement restriction device may be formed of at least two distinct and separable parts configured to be assembled into the movement restriction device after insertion in the patient’s body.According to an embodiment, a minimum width of the movement restriction device, as measured from side to side, may be 20 mm or larger, such as 30 mm or larger, such as 40 mm or larger, such as 50 mm or larger. According to some embodiments, the movement restriction device may comprise a first and a second portion, wherein the first and second portions are configured to be arranged on opposite sides of the cardia. In an example, the movement restriction device may be configured to be arranged such that a gap is formed between the second portion of the movement restriction device and the esophagus. In an example, the second portion of the movement restriction device may be configured to be at least partly invaginated by a second wall portion of the stomach.According to an embodiment, the movement restriction device may be configured to be arranged such that a portion of the first wall portion is arranged between the first portion of the movement restriction device and the esophagus.According to an embodiment, the movement restriction device may be configured to be at least partly invaginated by the first wall portion along at least half of the toroidal length of the movement restriction device. According to an embodiment, the movement restriction device may be configured to be invaginated when placed on the outside of the stomach wall.According to an embodiment, the movement restriction device may comprise two end portions configured to be coupled to each other to form a closed ring. The end portions may be configured to be releasably attached to each other.According to an embodiment, a poloidal circumference of the movement restriction device may be larger for the first portion and for the second portion. In an example, a minimum width of the first portion of the movement restriction device, as measured from side to side, is 20 mm or larger, such as 30 mm or larger, such as 40 mm or larger, such as 50 mm or larger. Alternatively, the width may be defined as a height measured along a normal to the plane in which the circumference extends.According to an embodiment, the movement restriction device may have a shape conforming to a torus.According to an embodiment, the movement restriction device may have C-shaped cross section.According to an embodiment, an upper portion of the movement restriction device may comprise a recess defined in the outer surface of the movement restriction device.According to an embodiment, a lower portion of the movement restriction device may comprise a curved outer surface, which may be arranged to face the esophagus. The curved outer surface may comprise a radius of curvature corresponding to or exceeding the radius of curvature of the esophagus.According to an embodiment, an elongated support, protruding from the movement restriction device, may be at least partly invaginated in the fundus before the fundus is attached to the esophagus. The support may be oriented along the esophagus.Exemplary embodiments of a core and a cover according to at least some of the above aspects will now be discussed. According to some embodiments, the core may be configured to allow a transition from the constricting state into the expanded state caused by the food passing through esophagus. The core may be configured to exert an encircling pressure on the esophagus in the constricting state.According to an embodiment, the apparatus may further comprise an attractor for resiliently attracting adjacent portions of the core to one another to generate the encircling pressure. The attractor may comprise an elastic element, and / or at least two mutually attracting magnets. Further, the apparatus may comprise a link connecting a first and a second one of said at least two magnets to each other. The link may be configured to extend into at least one of said magnets in response to said magnets moving towards each other.According to some embodiments, the core may comprise two end portions configured to be coupled to each other to form a closed ring around the esophagus. The end portions may be configured to be releasably attached to each other and may comprise a respective interlockable attacher.According to an embodiment, the core may comprise a plurality of core elements configured to be arranged in an annular array around the esophagus. The core may further comprise a plurality of links, wherein each link may extend between a respective pair of core elements arranged adjacent to each other. The links may be configured to allow the respective core elements to move towards and away from each other, and may be configured to extend into at least one of the core elements of the respective pair of core elements as the core elements move towards each other. According to an embodiment, the cover may comprise an array of tubular segments. According to some embodiments, the cover may comprise a biocompatible outer surface for long-term implantation. The cover may for example be configured to rest against an outer surface of the esophagus and may further comprise a surface for promoting tissue growth. The cover may for example be formed of a polymer material, such as silicone. In further examples, the cover may be formed of or comprise a carbon-based material, such as carbon fiber material. According to some embodiments, the cover may be formed of a material having a thickness of 0.1-10 mm, such as 1-5 mm. The cover may comprise at least one predefined fold along which the cover is allowed to fold in response to the core varying its length. The cover may in some examples comprise lowered and elevated portions allowing the cover to vary its length while maintaining its surface area. Thus, the cover may be configured to be compressible and expandable in its length direction, wherein the length is varied mainly due to the folding of the cover rather than elastic properties of the material. Thus, the cover may be considered to be formed of an inelastic material. In some examples, a length of the cover enclosing the at least a part of the core may exceed a length of the at least a part of the core when the at least a part of the core is arranged in the constricting state.Exemplary embodiments of the attacher, which comprises a shape and size that allows it to be invaginated by the wall portion to hinder rotation of the movement restriction device as set out above in connection with some of the aspects, will now be described in the following.According to some embodiments, a first end portion of the attacher may be configured to be invaginated by the wall portion and a second end portion to be attached to the movement restriction device. The first portion and the second portion may extend in different directions relative to each other, wherein the first portion may be configured to be invaginated by the wall portion to hinder rotation of the movement restriction device around a first axis, and wherein the second portion may be configured to be invaginated by the wall portion to hinder rotation of the movement restriction device around a second axis, different from the first axis. The first and second portions of the attacher may be curved to follow a curvature of the wall portion. The first portion and the second portion may be arranged at an angle to each other, the angle being in the interval of 60-120 degrees, such as 90 degrees.According to some embodiments, the attacher may be configured to be releasably attached to the movement restriction device. The attacher may be configured to allow a position of the movement restriction device to be adjusted after invagination of the attachment means. In some examples, the apparatus may be configured to allow a distance between the movement restriction device and the attacher to be varied to allow the position of the movement restriction device relative to the diaphragm to be adjusted. Further, the apparatus may be configured to allow an orientation of the movement restriction device relative to the attachments means to be varied to allow the position of the movement restriction device relative to the diaphragm to the adjusted.In an embodiment, the attacher may comprise a third portion, configured to be arranged to protrude from the wall portion when implanted, and to define a distance between the wall portion and the movement restriction device. The third portion may comprise a curvature allowing the third portion to be arranged to point away from the esophagus when implanted.According to an embodiment, the movement restriction device and the attacher may be integrally formed into a single piece.According to an embodiment, each of the movement restriction device and the attachments means may comprise a biocompatible outer surface. The attacher may comprises an outer surface configured to promote tissue growth. In some examples, the attacher may be formed of a metal. In further examples, the movement restriction device may be formed of a polymer.According to an embodiment, an outer surface of the movement restriction device may comprise a material for hindering growth of fibrotic tissue.Exemplary embodiments of the method of treating reflux disease in a human patient by implanting an apparatus comprising a movement restriction device and an elongated support device, as set out in some of the above aspects, will now be discussed in the following.According to an embodiment, the apparatus may be placed such that the movement restriction device rests against the outside of the fundus at a position between the cardiac sphincter and the portion of the fundus that is to be affixed to the esophagus. According to an embodiment, the apparatus may be placed such that the portion of the fundus that is affixed to the esophagus is arranged between the cardiac sphincter and the movement restriction device.According to an embodiment, the pouch may be formed to be open in a least two positions to form a tunnel through which the apparatus extends.According to an embodiment, the portion of the fundus may be affixed to the patient’s diaphragm.According to an embodiment, affixing the portion of the fundus to the esophagus may include suturing or stapling.According to an embodiment, the support device may comprise a first and a second end portion between which the esophagus can be introduced. The first and second end portions can be coupled to each other so as to fixate the support device to the esophagus in an encircling manner. According to an embodiment, the method may further comprise inserting a needle or a tube-like instrument into the patient’s abdomen, using the needle or tube-like instrument to fill the abdomen with a gas, placing at least two laparoscopic trocars in the abdomen, inserting a camera through one of the laparoscopic trocars into the abdomen, inserting at least one dissecting tool through one the laparoscopic trocars, dissecting a portion of the stomach, and at least partly closing the pouch by means of sutures, such as barbed sutures, or staples.In the following, exemplary embodiments of the method for affixing a fundus portion of the stomach of a human patient to the patient’s esophagus according to the above aspect will now be described.According to an embodiment, the abdominal part of the esophagus and the fundus can be divided by a plane into a ventral and a dorsal side. The method may comprise providing the first line on the dorsal side of the plane and the second line on the ventral side of the plane. The first line may begin less than 1 cm above the angle of His and the second line began less than 3 cm above the angle of His. The second line may in some examples begin at a distance less than 2 cm from the first line.According to an embodiment, a separating angle between the first line and the second line may be in the range of 90-150 degrees.According to some embodiments, the method may comprise providing an additional fastener between the first line and the second line, at the top of the fundus portion. In some examples, the fasteners may comprise staples. In some examples, the fasteners may comprise sutures, such as for example barbed sutures. The first line of fasteners may for example comprise a first continuous suture, and the second line of fasteners a second continuous suture.According to some embodiments, the method may further comprises placing a movement restriction device on the fundus, forming a pouch in the fundus, arranging the movement restriction device at least partly in the pouch, and invaginating the movement restriction device by the fundus by at least partly closing the pouch by fasteners. The movement restriction device may be arranged at a position between the diaphragm and the cardiac sphincter to hinder the cardia from sliding through the diaphragm opening into the patient’s thorax. The movement restriction device may be invaginated after affixing the fundus portion to the esophagus. Further, the pouch may be formed to be open in a least two positions to form a tunnel through which the movement restriction device may extend. In an example, the fundus may be affixed to the diaphragm.According to some embodiments an energy source may be provided. The energy source may be configured to be implanted in the body of the patient. The energy source may be configured to provide energy consuming components of the implant with electrical power. Examples of energy consuming components include controllers, sensors, electrodes, and the like, as outlined above in connection with the previous embodiments and examples. Thus, in some embodiments the energy source may be configured to provide the electrode arrangement, or electrode, as outlined above with electrical power. The implantable energy source may be configured to be arranged inside, or integrated with, the implanted device, such as the movement restriction device, support device, attachment means, core, or cover according to any of the embodiments and examples described above. In some examples the energy source, or a part of the energy source, may be configured to be implanted outside the apparatus or implanted device, such as for example subcutaneously.The energy source may comprise a primary cell, or galvanic cell, designed to be discarded after use, and not recharged like a secondary cell. Alternatively, or additionally the energy source may comprise a secondary cell, or rechargeable battery, designed to be recharged repeatedly. According to some embodiments, the implantable energy source may be configured to be charged by an external energy source, i.e., an energy source arranged outside the patient’s body. This may for example be achieved by means of an implantable charger, which may be configured to be electrically connected to the implantable energy source and to enable charging of the implantable energy source by the external energy source. Thus, the charger may be configured to transmit the electrical power from the outside of the patient’s body to the implanted energy source. The transmission may for example be performed wirelessly from the external source, and the charger may in some examples comprise an electromagnetic coil for facilitating the transfer.According to some embodiments, the charger may be configured to control the charging of the implantable energy source by controlling a receipt of electrical power from the external energy source at the implantable charger, and / or by controlling a transmission of electrical power from the external energy source to the implantable charger.According to some embodiments, the charging of the implantable energy source may be controlled based on a functional status of the implanted energy source. This may for example be realized by controlling the electrical power delivered or emitted by an external energy source, or by controlling the electrical power received by a charger as outlined above. Further, the charging may in some examples be controlled by controlling the electrical power delivered by the charger to the implantable energy source, either by controlling the power output from the charger or by controlling the power received or absorbed by the implantable energy source. Thus, it will be appreciated that the charging of the implantable energy source may be controlled by varying or controlling the electrical power, supplied by the external energy source, at any point along the way to the implantable energy source. As exemplified above, the electrical power that is supplied to the implantable energy source may hence be controlled at the external energy source, at the charger or at the implantable energy source itself.The functional status of the implanted energy source may for example include a charge level or a temperature. The temperature may for example be related to the energy source, the muscle tissue, or a part of the implant such as the electrode arrangement. Thus, the charging may be reduced or even stopped in case the charge level (or accumulated energy) reaches an upper limit, or in case the temperature exceeds a predetermined interval. According to some embodiments, there may be provided a controller (or processor or control circuitry) for controlling various parts or functions of the implanted device or apparatus according to any of the embodiments described above. The controller may for example be configured to include the functional status of the implanted energy source in a signal that is transmitted to the outside of the body.The controller may be configured to be operable connected to the electrode arrangement for controlling the electrical stimulation of the muscle tissue. The stimulation may for example be controlled such that the muscle tissue is stimulated by a series of electrical pulses. The electrical pulses may be characterized by their voltage and / or current. In some examples, a pulse of a first polarity may be followed by a pulse of a second, reversed polarity. The first polarity may for example be a positive current and the second polarity a negative current relative a current flow direction. Alternatively, or additionally the first polarity may be characterized by a positive voltage relative to a reference such as ground, and the second polarity by a negative voltage.The controller may be configured to generate a pulsed electrical stimulation signal comprising a pulse frequency of 0.01-150 Hz. The pulse duration may be 0.01-100 ms, and the pulse amplitude in the interval 1-15 mA. Specific examples of electrical stimulation signals may be characterized by a pulse frequency of 0.15-0.25 Hz, a pulse duration of 20-30 ms and a pulse amplitude of 3-10 mA. The controller may further be configured to generate a pulsed electrical stimulation signal having a varying composition, including different periods including build-up periods in which the amplitude is gradually increasing, stimulation periods in which the stimulation is ongoing, and pause periods wherein the stimulation is paused. Thus, in an example, the electrical stimulation signal may comprise a build-up period of 0.01-2 s, a stimulation period of 1-60 s, and a stimulation pause of 0.01-60 s. During the build-up period and the stimulation period the signal may comprises a pulse frequency of 1-50 Hz and a pulse duration of 0.1-10 ms. These periods may be varied and combined depending on the desired stimulation of the muscle tissue and may further be varied based on a response which fort example may be monitored by means of a sensor connected to the controller. The sensor may for example be configured to measure a motoric response in the muscle tissue, which may be measured as a mechanical movement or an electrical response.According to some embodiments, there may be provided an implantable sensor for sensing action potentials generated by pacemaker cells of the muscle tissue. The sensor may be communicatively coupled to the controller, which may be configured to control the electrical stimulation based at least partly on the sensed action potentials. This may be particularly advantageous when stimulating smooth muscle tissue, which may exhibit period contractions that are paced by the pacemaker cells. The present embodiments thus allow for the electrical stimulation signal to be tailored to amplify the sensed action potentials.According to some embodiments, the controller may comprise an external controller configured to be arranged outside the patient’s body, and an internal controller, or implantable controller, configured to be arranged inside the patient’s body. The wireless remote control may comprise an external signal transmitter configured to communicate with the internal controller. The internal controller may thus be configured to receive a signal transmitted by the external signal transmitter and to control an operation of the apparatus or medical implant based on the signal. The signal may in some examples be selected from the group consisting of: a sound signal, an ultrasound signal, an electromagnetic signal, and infrared signal, a visible light signal, an ultra violet light signal, a laser signal, a microwave signal, a radio wave signal, an X-ray radiation signal and a gamma radiation signal.According to an embodiment of the movement restriction device defined in any one of the aspects above, the average surface roughness is Ra as defined according to ISO 21920-2:2021.According to an embodiment of the movement restriction device defined in any one of the aspects above the average surface roughness is Sa as defined according to ISO 25178-2:2021.According to an embodiment of the movement restriction device defined in any one of the aspects above the average surface roughness is in the range of 0.1–0.5 µm. According to an embodiment of the movement restriction device defined in any one of the aspects above the average surface roughness is in the range of 0.1–0.3 µm. According to an embodiment of the movement restriction device defined in any one of the aspects above the implantable movement restriction device comprises a polymer material. According to an embodiment of the movement restriction device defined in any one of the aspects above implantable movement restriction device comprises at least one of a silicone-based material and a polyurethane-based material. According to an embodiment of the movement restriction device defined in any one of the aspects above second solid material comprises at least one of a polypropylene-based and a polyethylene-based material. According to an embodiment of the movement restriction device defined in any one of the aspects above, an indentation hardness on the Shore A scale measured on the outer surface is at least 50.According to an embodiment of the movement restriction device defined in any one of the aspects above indentation hardness is indentation hardness is measured by the durometer method defined in part 4 of ISO 48-4:2018.According to an embodiment of the movement restriction device defined in any one of the aspects above an indentation hardness on the Shore A scale measured on the outer surface is no more than 70.According to an embodiment of the movement restriction device defined in any one of the aspects above an indentation hardness on the Shore A scale measured on the outer surface is in the range of 55 to 65.According to an embodiment, the implantable movement restriction device comprises a core part and at least one outer part, configured to be assembled to the implantable movement restriction device.According to an embodiment, the core part comprises a fluid.According to an embodiment, the core part comprises a liquid having a density a below 1000 kg / m3.According to an embodiment, the liquid comprises at least one selected from a list of:oil-based liquids, andalcohol based liquids.According to an embodiment, the core part comprises a gas.According to an embodiment, the core part comprises a plurality of volumes of gas enclosed by an enclosing material.According to an embodiment, the core part comprises a solid polymer material enclosing the enclosing material, and wherein the enclosing material is harder than the solid polymer material. According to an embodiment, the plurality of volumes of gas enclosed by an enclosing material makes up at least 10 volume percent of the second volume, more preferably at least 20 volume percent of the second volume, and even more preferably at least 30 volume percent of the at least one outer part.According to an embodiment, the enclosing material comprises glass. According to an embodiment, the implantable movement restriction device comprises a contrast agent. According to an embodiment, the implantable movement restriction device comprises the contrast agent BaSO4.According to an embodiment, the implantable movement restriction device comprises the contrast agent in an amount of 1–15 % by weight of the implantable movement restriction device.According to an embodiment, the implantable movement restriction device comprises the contrast agent in an amount of 1–6% by weight of the implantable movement restriction device.According to an embodiment, the implantable movement restriction device comprises the contrast agent in an amount of 8–15 % by weight of the implantable movement restriction device.In some embodiments, the core part comprises the contrast agent in an amount of 8–15 % by weight of the core part.In some embodiments, the at least one outer part comprises the contrast agent in an amount of 1–6% by weight of the implantable movement restriction device.The various apparatuses and methods according to the above aspects can be combined with any of the features, examples and effects described in the present application. According to an embodiment of the movement restriction device defined in any one of the aspects above, the indentation hardness is indentation hardness is measured by the durometer method defined in part 4 of ISO 48-4:2018.According to an embodiment of the movement restriction device defined in any one of the aspects above an indentation hardness on the Shore A scale measured on the outer surface is no more than 70.According to an embodiment of the movement restriction device defined in any one of the aspects above an indentation hardness on the Shore A scale measured on the outer surface is in the range of 55 to 65.According to an embodiment, the core part comprises a fluid.Accordi ng to an embodiment, the core part comprises a liquid having a density a below 1000 kg / m3.According to an embodiment, the liquid comprises at least one selected from a list of:oil-based liquids, and alcohol based liquids.According to an embodiment, the core part comprises a gas.According to an embodiment, the core part comprises a plurality of volumes of gas enclosed by an enclosing material.According to an embodiment, the core part comprises a solid polymer material enclosing the enclosing material, and wherein the enclosing material is harder than the solid polymer material. According to an embodiment, the plurality of volumes of gas enclosed by an enclosing material makes up at least 10 volume percent of the second volume, more preferably at least 20 volume percent of the second volume, and even more preferably at least 30 volume percent of the at least one outer part.According to an embodiment, the enclosing material comprises glass.An implantable medical device for treating reflux disease is further provided. The implantable medical device comprises a movement restriction device configured to be fixated to the stomach wall for hindering movement of the lower esophageal sphincter relative to the thoracic diaphragm. The movement restriction device comprises a first part, a second part, and a first distance element. The first and second part are configured to be connected to each other for forming at least a portion of a functional movement restriction device. The first and second part are capable of disconnecting from each other, such that the first and second part individually can pass through the gastro-intestinal tract, and the first distance element is configured to create a space located between the first and second part. The space is configured to allow in-growth of fibrotic tissue between portions of the first and second parts. The space is confined at least partially by a first surface of the first part and a second surface of the second part and wherein the first and second surfaces are positioned opposite each other when the first and second parts are connected. A line segment of a first straight line is bounded by a first point on the first surface and a second point on the second surface, the line segment of the first straight line is more than 1mm. A line segment of a second straight line is bounded by a third point on the first surface and a fourth point on the second surface. The line segment of the second straight line is more than 1mm and the first straight line is parallel to the second straight line. The first and second straight lines intersect a third straight line which also intersects the center of gravity of the functional movement restriction device, anda distance between the first and second straight lines is more than 2mm for allowing in-growth of fibrotic tissue for aiding in the fixation of the functional movement restriction device to the stomach wall.According to one embodiment, the first distance element is integrated in at least one of the first and second part, and the first distance element may protrude from a surface of at least one of the first and second part.According to one embodiment, the implantable medical device further comprises a first separate distance part comprising the first distance element. According to one embodiment, at least one of the first and second part may further comprise a recess configured to receive a portion of the first distance element.The first distance element may in any of the embodiments herein comprise at least a first and second portion configured to be placed at a distance from each other.According to one embodiment, the implantable medical device further comprises at least a third part, and the first, second and third parts may be configured to be connected to each other for forming at least a portion of the functional movement restriction device.The implantable medical device according to any one of the embodiments herein may further comprise a second distance element, and the first distance element may be configured to create a space between the first and second part and the second distance element may be configured to create a space between the first and third part. The first and second distance element may be portions of a separate distance part. According to one embodiment, at least one of the first, second and third parts may comprise a recess configured to receive a portion of the distance element.According to one embodiment, the space created by the distance element may have a volume exceeding 100mm3.According to one embodiment, the space forms a recess in the implantable medical device, and the recess has a depth exceeding 2mm and a width exceeding 1mm. According to one embodiment, the distance element is configured to prevent at least one of:rotation between the first and second part, linear movement between the first and second part in a first direction, and linear movement between the first and second part in a first and second direction.According to one embodiment, the first separate distance part is configured to be placed centrally in the functional movement restriction device, and the center of gravity of the first separate distance part may substantially coincide with the center of gravity of the functional movement restriction device.According to one embodiment, the first separate distance part comprises at least one rim comprising at least a first and a second surface. The first surface of the rim may be configured to engage a surface of the first part and the second surface of the flange is configured to engage a surface of the second part. The first and second surfaces of the at least one rim may be parallel. The first separate distance part may comprise at least two rims. The first rim may comprise at least a first and a second surface, the first surface of the first rim may be configured to engage a surface of the first part and the second surface of the first rim may be configured to engage a surface of the second part. The second rim may comprise at least a first and a second surface, and the first surface of the second rim may be configured to engage a surface of the first part and the second surface of the second rim may be configured to engage a surface of the third part.According to one embodiment, the first surfaces of the first rim and the first surface of the second rim are angled relative to each other with an angle in the range 20° - 70°. According to one embodiment, the first surfaces of the first rim and the first surface of the second rim are angled relative to each other with an angle in the range 40° - 50°.According to one embodiment, the first surfaces of the first rim and the first surface of the second rim are perpendicular.According to one embodiment, the first distance element may be configured to engage the recess in at least one of the first and second part in a direction of a length axis of the distance element, and the portion of the first distance element configured to enter the recess of the second part may comprise at least one surface being angled relative to the length axis of the distance element. According to one embodiment, the surface of the first distance element being angled may be configured to face a surface of the recess in at least one of the first and second part being angled with an angle different from the angle of the first distance element, and wherein a point on the angled surface of the first distance element is configured to abut a point on the angled surface of the recess.According to one embodiment, the angled surface of the first distance element abuts the angled surface of the recess over a length being less than half of the length of the angled surface of the first distance element.According to one embodiment, the angled surface of the first distance element abuts the angled surface of the recess over a length being less than one third of the length of the angled surface of the first distance element.According to one embodiment, the angled surface of the first distance element abuts the angled surface of the recess over a length being less than half of the depth of the recess, measured in a direction coinciding with the direction of the length axis of the first distance element, when the portion of the first distance element is inserted into the recess. According to one embodiment, the portion of the first distance element configured to enter the recess of the second part comprises a tapered portion. According to one embodiment, the tapered portion is tapered with an angle in the range 20° - 100°. According to one embodiment, the recess in at least one of the first and second part is tapered, such that two surfaces on opposite sides of the tapered portion of the first distance element faces two surfaces on opposite sides of the tapered recess, when the tapered portion of the first distance element is inserted into the recess. The tapered recess may be tapered with an angle in the range 30° - 135°. According to one embodiment, the tapered portion of the first distance element is tapered with a first angle and the tapered recess in at least one of the first and second part is tapered with a second angle, and the second angle is larger than the first angle. The second angle may be more than 3° larger than the first angle, or more than 5° larger than the first angle, or more than 10° larger than the first angle.According to one embodiment, the tapered portion of the first distance element, and the tapered recess in at least one of the first and second part is conical or frustum-conical.According to one embodiment, the tapered portion of the first distance element has the shape of a pyramid with a polygonal base.According to one embodiment, the portion of the first distance element configured to enter the recess of the first or second part comprises at least one surface having a curvature. According to one embodiment, the surface of the first distance element having a curvature is configured to face a surface of the recess in at least one of the first and second part. A point on the surface of the first distance element having the curvature is configured to abut a point on the surface of the recess. According to one embodiment, the surface of the first distance element having a curvature abuts the surface of the recess over a length being less than half of the length of the angled surface of the first distance element, when the first distance element has been positioned in the recess in at least one of the first and second part.According to one embodiment, the surface of the first distance element having a curvature abuts the surface of the recess over a length being less than one third of the length of the angled surface of the first distance element, when the portion of the first distance element is inserted into the recess.According to one embodiment, the surface of the first distance element having a curvature abuts the surface of the recess over a length being less than one third of the length of the angled surface of the first distance element, when the portion of the first distance element is inserted into the recess.According to one embodiment, the surface of the first distance element having a curvature abuts the surface of the recess over a length being less than half of the depth of the recess, measured in a direction coinciding with the direction of the length axis of the first distance element, when the portion of the first distance element is inserted into the recess. According to one embodiment, the portion of the first distance element configured to enter the recess of the second part comprises at least one surface having a first and second curvature extending in perpendicular directions. The portion of the first distance element configured to enter the recess of the second part may comprise at least one spherical surface.According to one embodiment, the recess in at least one of the first and second part is tapered, such that two curved surfaces on opposite sides of the portion of the first distance element configured to enter the recess of the first or second part faces two surfaces on opposite sides of the tapered recess, when the portion of the first distance element configured to enter the recess of the first or second part is inserted into the recess. According to one embodiment, the recess in at least one of the first and second part comprises at least one surface having a curvature. The recess in at least one of the first and second part may comprise at least one surface having a first and second curvature extending in perpendicular directions.According to one embodiment, the recess in at least one of the first and second part comprises at least one spherical surface.According to one embodiment, the portion of the first distance element configured to enter the recess of the first or second part comprises at least one surface having a curvature with a first radius and the recess in at least one of the first and second part comprises at least one surface having a curvature with a second radius. The second radius is according to one embodiment longer than the first radius.According to one embodiment, the portion of the first distance element configured to enter the recess of the first or second part comprises at least one surface having a first and second curvature extending in perpendicular directions. According to one embodiment, the recess in at least one of the first and second part comprises at least one surface having a first and second curvature extending in perpendicular directions, and the sum of the radii of the first and second curvatures of the recess in at least one of the first and second part is longer than the sum of the radii of the first and second curvature of the portion of the first distance element configured to enter the recess.According to one embodiment, the functional movement restriction device or the boundary of the functional movement restriction device may be elongated. The functional movement restriction device may be elongated such that a longest length is more than 1,5 times a widest width. According to one embodiment, the functional movement restriction device comprises a bend, and the functional movement restriction device comprises a bent center axis following the elongation of the functional movement restriction device.According to one embodiment, a first portion of the functional movement restriction device is configured to be positioned such that a first portion of the bent center axis is parallel to the caudal-cranial axis of the patient, and a second portion of the bent center axis is angled relative to the caudal-cranial axis of the patient, with an angle exceeding 5°. According to one embodiment, the second portion of the bent center axis is configured to bepositioned in the stomach such that it is angled towards the esophagus.According to one embodiment, at least one of the first and second part has a shape corresponding to an ellipsoid wedge or a truncated ellipsoid wedge.According to one embodiment, at least one of the first and second part has a shape corresponding to a spherical wedge or a truncated spherical wedge.At least one of the first and second part may have a shape corresponding to a portion of an ellipsoid wedge or a portion of a truncated ellipsoid wedge.According to one embodiment, at least one of the first and second part has a shape corresponding to a hemiellipsoid wedge or a truncated hemiellipsoid wedge.At least one of the first and second part may have a shape corresponding to a portion of a spherical wedge or a portion of a truncated spherical wedge.According to one embodiment, at least one of the first and second part has a shape corresponding to a hemispherical wedge or a truncated hemispherical wedge.According to one embodiment, at least one of the first and second part has a shape corresponding to an ellipsoid segment or a portion of an ellipsoid segment.According to one embodiment, at least one of the first and second part has a shape corresponding to a spherical segment or a portion of a spherical segment.The functional movement restriction device, or the boundary of the functional movement restriction device, may in any of the embodiments have a shape corresponding to an ellipsoid or a truncated ellipsoid.According to one embodiment, the functional movement restriction device, or the boundary of the functional movement restriction device, has a shape corresponding to a sphere or a truncated sphere.According to one embodiment, at least the periphery of at least one of the first and second part has a shape corresponding to a cylinder.According to one embodiment, the combined periphery of the first and second part has a shape corresponding to a cylinder.According to one embodiment, the periphery of the first part has a shape corresponding to a first cylinder having a first radius, and the periphery of the second part has a shape corresponding to a second cylinder having a second radius, and the first and second radii are different.According to one embodiment, the functional movement restriction device, or the boundary of the functional movement restriction device, comprises a stadium shaped cross-section, or a truncated stadium shaped cross-section. According to one embodiment, the functional movement restriction device comprises a bent stadium shaped cross-section, or a truncated bent stadium shaped cross-section. According to one embodiment, a periphery of the first part has a shape corresponding to a cylinder or an ellipsoid segment, and a periphery of the second part has a shape corresponding to a cylinder or an ellipsoid segment, and the first part comprises at least one protrusion protruding from a first base surface and the second part comprises at least one recess in a first base surface, and the at least one protrusion is adapted to be placed at least partially in the at least one recess. The at least one protrusion may be adapted to engage the at least one recess and the first part may further comprise at least one recess in a second base surface.The position of the at least one protrusion may coincide with the position of the at least one recess, such that the recess overlaps the protrusion when the first part is viewed in a direction normal to the first base surface. The at least one recess may recess into the at least one protrusion.According to one embodiment, the at least one protrusion may have the shape of a pyramid with a polygonal base. According to one embodiment, the first part further comprises at least one protrusion in a second base surface, and the second part may further comprise at least one protrusion in a second base surface. The second part may further comprise at least one recess in a second base surface.According to one embodiment, the implantable medical device further comprises a third part, and the first part further comprises a recess in a second base surface, the second part further comprises a protrusion protruding from a second base surface, the third part comprises a protrusion protruding from a first base surface and a recess in a second base surface, the protrusion of the first part is configured to be at least partially inserted into the recess of the second part, the protrusion of the second part is configured to be at least partially inserted into the recess of the third part, and the first, second and third parts are configured to be assembled for forming at least a portion of a functional implantable medical device, and wherein the recesses and protrusions stabilize the parts relative to each other when assembled. According to one embodiment, the area of the first base surface of the first part is smaller than the area of the first base surface of the second part.According to one embodiment, the at least one protrusion protruding from the first base surface of the first part comprises the distance element.According to one embodiment, the medical device is further configured to treat obesity by the movement restriction device being configured to protrude into the stomach and thereby reducing the volume of the cavity of the stomach. For the purpose of treating obesity, the functional movement restriction device may have a volume in the range 100cm3 – 1000cm3, or in the range 100cm3 – 500cm3. For the purpose of treating obesity, the functional implantable medical device may have a length in the range 2,5cm – 15cm or in the range 5cm – 15cm, or in the range 7cm – 15cm, or in the range 8cm – 15cm, or in the range 8cm – 12cm. The movement restriction device may in any of the embodiments herein comprises a surface friction reducing coating covering at least a part of the surface of the movement restriction device. The surface friction reducing coating may be configured to reduce the friction between the movement restriction device and the tissue of the stomach wall by which the movement restriction device is at least partially invaginated.The implantable medical device may further comprise a sensor configured to sense at least one of a force and a pressure, for monitoring a pressure or force exerted by the implantable movement restriction device on the stomach wall of the patient.According to one embodiment, the movement restriction device comprises a first portion having a first volume enclosed by material of the implantable movement restriction device and a second portion, different from the first portion, having a second volume enclosed by material of the implantable movement restriction device. The first volume and the second volumes may be equally large and the first volume may have a higher density than the second volume, and the second volume may have a density below 1000 kg / m3.According to one embodiment, the implantable medical device may be configured to be fixated to the stomach wall of the patient to act as a movement restriction device for hindering movement of the lower esophageal sphincter relative to the thoracic diaphragm. The movement restriction device comprises a first part, a second part, and a distance element. The first and second part may be configured to be connected to each other for forming at least a portion of a functional movement restriction device. The first and second parts are capable of disconnecting from each other if at least one of the first and second part becomes positioned inside of the stomach, such that the first and second part individually can pass through the gastro-intestinal tract, and the distance element is configured to create a space between the first and second part. The space is configured to allow in-growth of fibrotic tissue between portions of the first and second parts, and the space forms a recess in the functional movement restriction device. The recess may be more than 1mm wide and more than 2mm deep for allowing in-growth of fibrotic tissue for aiding in the fixation of the functional movement restriction device to the stomach wall.According to one embodiment, the first distance element is integrated in at least one of the first and second part, and the first distance element may protrude from a surface of at least one of the first and second part.According to one embodiment, the implantable medical device further comprises a first separate distance part comprising the first distance element. According to one embodiment, at least one of the first and second part may further comprise a recess configured to receive a portion of the first distance element.The first distance element may in any of the embodiments herein comprise at least a first and second portion configured to be placed at a distance from each other.According to one embodiment, the implantable medical device further comprises at least a third part, and the first, second and third parts may be configured to be connected to each other for forming at least a portion of the functional movement restriction device.The implantable medical device according to any one of the embodiments herein may further comprise a second distance element, and the first distance element may be configured to create a space between the first and second part and the second distance element may be configured to create a space between the first and third part. The first and second distance element may be portions of a separate distance part. According to one embodiment, at least one of the first, second and third parts may comprise a recess configured to receive a portion of the distance element.According to one embodiment, the space created by the distance element may have a volume exceeding 100mm3.According to one embodiment, the space forms a recess in the implantable medical device, and the recess has a depth exceeding 2mm and a width exceeding 1mm. According to one embodiment, the distance element is configured to prevent at least one of:rotation between the first and second part, linear movement between the first and second part in a first direction, and linear movement between the first and second part in a first and second direction.According to one embodiment, the first separate distance part is configured to be placed centrally in the functional movement restriction device, and the center of gravity of the first separate distance part may substantially coincide with the center of gravity of the functional movement restriction device.According to one embodiment, the first separate distance part comprises at least one rim comprising at least a first and a second surface. The first surface of the rim may be configured to engage a surface of the first part and the second surface of the flange is configured to engage a surface of the second part. The first and second surfaces of the at least one rim may be parallel. The first separate distance part may comprise at least two rims. The first rim may comprise at least a first and a second surface, the first surface of the first rim may be configured to engage a surface of the first part and the second surface of the first rim may be configured to engage a surface of the second part. The second rim may comprise at least a first and a second surface, and the first surface of the second rim may be configured to engage a surface of the first part and the second surface of the second rim may be configured to engage a surface of the third part.According to one embodiment, the first surfaces of the first rim and the first surface of the second rim are angled relative to each other with an angle in the range 20° - 70°. According to one embodiment, the first surfaces of the first rim and the first surface of the second rim are angled relative to each other with an angle in the range 40° - 50°.According to one embodiment, the first surfaces of the first rim and the first surface of the second rim are perpendicular.According to one embodiment, the first distance element may be configured to engage the recess in at least one of the first and second part in a direction of a length axis of the distance element, and the portion of the first distance element configured to enter the recess of the second part may comprise at least one surface being angled relative to the length axis of the distance element. According to one embodiment, the surface of the first distance element being angled may be configured to face a surface of the recess in at least one of the first and second part being angled with an angle different from the angle of the first distance element, and wherein a point on the angled surface of the first distance element is configured to abut a point on the angled surface of the recess.According to one embodiment, the angled surface of the first distance element abuts the angled surface of the recess over a length being less than half of the length of the angled surface of the first distance element.According to one embodiment, the angled surface of the first distance element abuts the angled surface of the recess over a length being less than one third of the length of the angled surface of the first distance element.According to one embodiment, the angled surface of the first distance element abuts the angled surface of the recess over a length being less than half of the depth of the recess, measured in a direction coinciding with the direction of the length axis of the first distance element, when the portion of the first distance element is inserted into the recess. According to one embodiment, the portion of the first distance element configured to enter the recess of the second part comprises a tapered portion. According to one embodiment, the tapered portion is tapered with an angle in the range 20° - 100°. According to one embodiment, the recess in at least one of the first and second part is tapered, such that two surfaces on opposite sides of the tapered portion of the first distance element faces two surfaces on opposite sides of the tapered recess, when the tapered portion of the first distance element is inserted into the recess. The tapered recess may be tapered with an angle in the range 30° - 135°. According to one embodiment, the tapered portion of the first distance element is tapered with a first angle and the tapered recess in at least one of the first and second part is tapered with a second angle, and the second angle is larger than the first angle. The second angle may be more than 3° larger than the first angle, or more than 5° larger than the first angle, or more than 10° larger than the first angle.According to one embodiment, the tapered portion of the first distance element, and the tapered recess in at least one of the first and second part is conical or frustum-conical.According to one embodiment, the tapered portion of the first distance element has the shape of a pyramid with a polygonal base.According to one embodiment, the portion of the first distance element configured to enter the recess of the first or second part comprises at least one surface having a curvature. According to one embodiment, the surface of the first distance element having a curvature is configured to face a surface of the recess in at least one of the first and second part. A point on the surface of the first distance element having the curvature is configured to abut a point on the surface of the recess. According to one embodiment, the surface of the first distance element having a curvature abuts the surface of the recess over a length being less than half of the length of the angled surface of the first distance element, when the first distance element has been positioned in the recess in at least one of the first and second part.According to one embodiment, the surface of the first distance element having a curvature abuts the surface of the recess over a length being less than one third of the length of the angled surface of the first distance element, when the portion of the first distance element is inserted into the recess.According to one embodiment, the surface of the first distance element having a curvature abuts the surface of the recess over a length being less than one third of the length of the angled surface of the first distance element, when the portion of the first distance element is inserted into the recess.According to one embodiment, the surface of the first distance element having a curvature abuts the surface of the recess over a length being less than half of the depth of the recess, measured in a direction coinciding with the direction of the length axis of the first distance element, when the portion of the first distance element is inserted into the recess. According to one embodiment, the portion of the first distance element configured to enter the recess of the second part comprises at least one surface having a first and second curvature extending in perpendicular directions. The portion of the first distance element configured to enter the recess of the second part may comprise at least one spherical surface.According to one embodiment, the recess in at least one of the first and second part is tapered, such that two curved surfaces on opposite sides of the portion of the first distance element configured to enter the recess of the first or second part faces two surfaces on opposite sides of the tapered recess, when the portion of the first distance element configured to enter the recess of the first or second part is inserted into the recess. According to one embodiment, the recess in at least one of the first and second part comprises at least one surface having a curvature. The recess in at least one of the first and second part may comprise at least one surface having a first and second curvature extending in perpendicular directions.According to one embodiment, the recess in at least one of the first and second part comprises at least one spherical surface.According to one embodiment, the portion of the first distance element configured to enter the recess of the first or second part comprises at least one surface having a curvature with a first radius and the recess in at least one of the first and second part comprises at least one surface having a curvature with a second radius. The second radius is according to one embodiment longer than the first radius.According to one embodiment, the portion of the first distance element configured to enter the recess of the first or second part comprises at least one surface having a first and second curvature extending in perpendicular directions. According to one embodiment, the recess in at least one of the first and second part comprises at least one surface having a first and second curvature extending in perpendicular directions, and the sum of the radii of the first and second curvatures of the recess in at least one of the first and second part is longer than the sum of the radii of the first and second curvature of the portion of the first distance element configured to enter the recess.According to one embodiment, the functional movement restriction device or the boundary of the functional movement restriction device may be elongated. The functional movement restriction device may be elongated such that a longest length is more than 1,5 times a widest width. According to one embodiment, the functional movement restriction device comprises a bend, and the functional movement restriction device comprises a bent center axis following the elongation of the functional movement restriction device.According to one embodiment, a first portion of the functional movement restriction device is configured to be positioned such that a first portion of the bent center axis is parallel to the caudal-cranial axis of the patient, and a second portion of the bent center axis is angled relative to the caudal-cranial axis of the patient, with an angle exceeding 5°. According to one embodiment, the second portion of the bent center axis is configured to bepositioned in the stomach such that it is angled towards the esophagus.According to one embodiment, at least one of the first and second part has a shape corresponding to an ellipsoid wedge or a truncated ellipsoid wedge.According to one embodiment, at least one of the first and second part has a shape corresponding to a spherical wedge or a truncated spherical wedge.At least one of the first and second part may have a shape corresponding to a portion of an ellipsoid wedge or a portion of a truncated ellipsoid wedge.According to one embodiment, at least one of the first and second part has a shape corresponding to a hemiellipsoid wedge or a truncated hemiellipsoid wedge.At least one of the first and second part may have a shape corresponding to a portion of a spherical wedge or a portion of a truncated spherical wedge.According to one embodiment, at least one of the first and second part has a shape corresponding to a hemispherical wedge or a truncated hemispherical wedge.According to one embodiment, at least one of the first and second part has a shape corresponding to an ellipsoid segment or a portion of an ellipsoid segment.According to one embodiment, at least one of the first and second part has a shape corresponding to a spherical segment or a portion of a spherical segment.The functional movement restriction device, or the boundary of the functional movement restriction device, may in any of the embodiments have a shape corresponding to an ellipsoid or a truncated ellipsoid.According to one embodiment, the functional movement restriction device, or the boundary of the functional movement restriction device, has a shape corresponding to a sphere or a truncated sphere.According to one embodiment, at least the periphery of at least one of the first and second part has a shape corresponding to a cylinder.According to one embodiment, the combined periphery of the first and second part has a shape corresponding to a cylinder.According to one embodiment, the periphery of the first part has a shape corresponding to a first cylinder having a first radius, and the periphery of the second part has a shape corresponding to a second cylinder having a second radius, and the first and second radii are different.According to one embodiment, the functional movement restriction device, or the boundary of the functional movement restriction device, comprises a stadium shaped cross-section, or a truncated stadium shaped cross-section. According to one embodiment, the functional movement restriction device comprises a bent stadium shaped cross-section, or a truncated bent stadium shaped cross-section. According to one embodiment, a periphery of the first part has a shape corresponding to a cylinder or an ellipsoid segment, and a periphery of the second part has a shape corresponding to a cylinder or an ellipsoid segment, and the first part comprises at least one protrusion protruding from a first base surface and the second part comprises at least one recess in a first base surface, and the at least one protrusion is adapted to be placed at least partially in the at least one recess. The at least one protrusion may be adapted to engage the at least one recess and the first part may further comprise at least one recess in a second base surface.The position of the at least one protrusion may coincide with the position of the at least one recess, such that the recess overlaps the protrusion when the first part is viewed in a direction normal to the first base surface. The at least one recess may recess into the at least one protrusion.According to one embodiment, the at least one protrusion may have the shape of a pyramid with a polygonal base. According to one embodiment, the first part further comprises at least one protrusion in a second base surface, and the second part may further comprise at least one protrusion in a second base surface. The second part may further comprise at least one recess in a second base surface.According to one embodiment, the implantable medical device further comprises a third part, and the first part further comprises a recess in a second base surface, the second part further comprises a protrusion protruding from a second base surface, the third part comprises a protrusion protruding from a first base surface and a recess in a second base surface, the protrusion of the first part is configured to be at least partially inserted into the recess of the second part, the protrusion of the second part is configured to be at least partially inserted into the recess of the third part, and the first, second and third parts are configured to be assembled for forming at least a portion of a functional implantable medical device, and wherein the recesses and protrusions stabilize the parts relative to each other when assembled. According to one embodiment, the area of the first base surface of the first part is smaller than the area of the first base surface of the second part.According to one embodiment, the at least one protrusion protruding from the first base surface of the first part comprises the distance element.According to one embodiment, the medical device is further configured to treat obesity by the movement restriction device being configured to protrude into the stomach and thereby reducing the volume of the cavity of the stomach. For the purpose of treating obesity, the functional movement restriction device may have a volume in the range 100cm3 – 1000cm3, or in the range 100cm3 – 500cm3. For the purpose of treating obesity, the functional implantable medical device may have a length in the range 2,5cm – 15cm or in the range 5cm – 15cm, or in the range 7cm – 15cm, or in the range 8cm – 15cm, or in the range 8cm – 12cm. The movement restriction device may in any of the embodiments herein comprises a surface friction reducing coating covering at least a part of the surface of the movement restriction device. The surface friction reducing coating may be configured to reduce the friction between the movement restriction device and the tissue of the stomach wall by which the movement restriction device is at least partially invaginated.The implantable medical device may further comprise a sensor configured to sense at least one of a force and a pressure, for monitoring a pressure or force exerted by the implantable movement restriction device on the stomach wall of the patient.According to one embodiment, the movement restriction device comprises a first portion having a first volume enclosed by material of the implantable movement restriction device and a second portion, different from the first portion, having a second volume enclosed by material of the implantable movement restriction device. The first volume and the second volumes may be equally large and the first volume may have a higher density than the second volume, and the second volume may have a density below 1000 kg / m3.An implantable medical device for treating reflux disease, the implantable medical device comprising a movement restriction device configured to be fixated to the stomach wall for hindering movement of the lower esophageal sphincter relative to the thoracic diaphragm is further provided. The movement restriction device comprises a first part and a second part. The first and second parts are configured to be connected to each other for forming at least a portion of a functional movement restriction device. The first and second parts are capable of disconnecting from each other, such that the first and second part individually can pass through the gastro-intestinal tract, and a periphery of the first part has a shape corresponding to a cylinder or an ellipsoid segment, and a periphery of the second part has a shape corresponding to a cylinder or an ellipsoid segment. The first part comprises at least one protrusion protruding from a first base surface and the second part comprises at least one recess in a first base surface, and the at least one protrusion is adapted to be placed at least partially in the at least one recess for stabilizing the first and second parts relative to each other. According to one embodiment, at least one protrusion of a first part the movement restriction device is adapted to engage at least one recess of a second part of the movement restriction device.According to one embodiment, the first part further comprises at least one recess in a second base surface. According to one embodiment, the position of the at least one protrusion coincides with the position of the at least one recess, such that the recess overlaps the protrusion when the first part is viewed in a direction normal to the first base surface. The at least one recess may recess into the at least one protrusion.According to one embodiment, the at least one protrusion is adapted to engage the at least one recess in a direction of a length axis of the protrusion, and the portion of the protrusion adapted to be placed at least partially in the at least one recess comprises at least one surface being angled relative to the length axis of the protrusion. According to one embodiment, the surface of the protrusion is being angled is configured to face a surface of the recess in the second part being angled with an angle different from the angle of the protrusion. A point on the angled surface of the protrusion is configured to abut a point on the angled surface of the recess.According to one embodiment, the angled surface of the protrusion abuts the angled surface of the recess over a length being less than half of the length of the angled surface of the protrusion.An angled surface of the protrusion may abut the angled surface of the recess over a length being less than one third of the length of the angled surface of protrusion.According to one embodiment, the angled surface of the protrusion abuts the angled surface of the recess over a length being less than half of the depth of the recess, measured in a direction coinciding with the direction of the length axis of the protrusion, when the portion of the protrusion is inserted into the recess. According to one embodiment, the portion of the protrusion configured to enter the recess of the second part comprises a tapered portion, and the tapered portion may be tapered with an angle in the range 20° - 150°. According to one embodiment, the recess in at least one of the first and second part is tapered, such that two surfaces on opposite sides of the tapered portion of the protrusion faces two surfaces on opposite sides of the tapered recess, when the tapered portion of the first distance element is inserted into the recess. The tapered recess may be tapered with an angle in the range 30° - 155°. According to one embodiment, the tapered portion of the protrusion is tapered with a first angle and the tapered recess in at least one of the first and second part is tapered with a second angle, and the second angle is larger than the first angle. The second angle may be more than 3° larger than the first angle, or more than 5° larger than the first angle, or more than 10° larger than the first angle.According to one embodiment, the at least one protrusion has the shape of a pyramid with a polygonal base. According to one embodiment, the first part further comprises at least one protrusion in a second base surface, and the second part further comprises at least one protrusion in a second base surface. The second part may further comprise at least one recess in a second base surface.According to one embodiment, the implantable medical device further comprises a third part. The first part further comprises a recess in a second base surface, the second part further comprises a protrusion protruding from a second base surface, the third part comprises a protrusion protruding from a first base surface and a recess in a second base surface. The protrusion of the first part is configured to be at least partially inserted into the recess of the second part, the protrusion of the second part is configured to be at least partially inserted into the recess of the third part, and wherein the first, second and third parts are configured to be assembled for forming at least a portion of a functional implantable medical device, and wherein the recesses and protrusions stabilize the parts relative to each other when assembled. According to one embodiment, the area of the first base surface of the first part is smaller than the area of the first base surface of the second part.The functional movement restriction device, or the boundary of the functional movement restriction device, may in any of the embodiments have a shape corresponding to an ellipsoid or a truncated ellipsoid.According to one embodiment, the functional movement restriction device, or the boundary of the functional movement restriction device, has a shape corresponding to a sphere or a truncated sphere.According to one embodiment, at least the periphery of at least one of the first and second part has a shape corresponding to a cylinder.According to one embodiment, the combined periphery of the first and second part has a shape corresponding to a cylinder.According to one embodiment, the periphery of the first part has a shape corresponding to a first cylinder having a first radius, and the periphery of the second part has a shape corresponding to a second cylinder having a second radius, and the first and second radii are different.According to one embodiment, the functional movement restriction device, or the boundary of the functional movement restriction device, comprises a stadium shaped cross-section, or a truncated stadium shaped cross-section. According to one embodiment, the functional movement restriction device comprises a bent stadium shaped cross-section, or a truncated bent stadium shaped cross-section. According to one embodiment, the functional movement restriction device or the boundary of the functional movement restriction device may be elongated. The functional movement restriction device may be elongated such that a longest length is more than 1,5 times a widest width. According to one embodiment, the functional movement restriction device comprises a bend, and the functional movement restriction device comprises a bent center axis following the elongation of the functional movement restriction device.According to one embodiment, a first portion of the functional movement restriction device is configured to be positioned such that a first portion of the bent center axis is parallel to the caudal-cranial axis of the patient, and a second portion of the bent center axis is angled relative to the caudal-cranial axis of the patient, with an angle exceeding 5°. According to one embodiment, the second portion of the bent center axis is configured to bepositioned in the stomach such that it is angled towards the esophagus.According to one embodiment, the protrusion comprises a first distance element configured to create a space located between the first and second part. The space is configured to allow in-growth of fibrotic tissue between portions of the first and second parts, and wherein the space is confined at least partially by a first surface of the first part and a second surface of the second part and wherein the first and second surfaces are positioned opposite each other when the first and second parts are connected. A line segment of a first straight line is bounded by a first point on the first surface and a second point on the second surface. The line segment of the first straight line is more than 1mm. A line segment of a second straight line is bounded by a third point on the first surface and a fourth point on the second surface. The line segment of the second straight line is more than 1mm and the first straight line is parallel to the second straight line. The first and second straight lines intersect a third straight line which also intersects the center of gravity of the functional movement restriction device, and a distance between the first and second straight lines is more than 2mm for allowing in-growth of fibrotic tissue for aiding in the fixation of the functional movement restriction device to the stomach wall.According to one embodiment, the protrusion comprises a first distance element configured to create a space located between the first and second part. The space is configured to allow in-growth of fibrotic tissue between portions of the first and second parts and the space forms a recess in the functional implantable medical device. The recess is more than 1mm wide and more than 2mm deep for allowing in-growth of fibrotic tissue for aiding in the fixation of the functional implantable medical device to the stomach wall.According to one embodiment, the medical device is further configured to treat obesity by the movement restriction device being configured to protrude into the stomach and thereby reducing the volume of the cavity of the stomach. For the purpose of treating obesity, the functional movement restriction device may have a volume in the range 100cm3 – 1000cm3, or in the range 100cm3 – 500cm3. For the purpose of treating obesity, the functional implantable medical device may have a length in the range 2,5cm – 15cm or in the range 5cm – 15cm, or in the range 7cm – 15cm, or in the range 8cm – 15cm, or in the range 8cm – 12cm. The movement restriction device may in any of the embodiments herein comprises a surface friction reducing coating covering at least a part of the surface of the movement restriction device. The surface friction reducing coating may be configured to reduce the friction between the movement restriction device and the tissue of the stomach wall by which the movement restriction device is at least partially invaginated.The implantable medical device may further comprise a sensor configured to sense at least one of a force and a pressure, for monitoring a pressure or force exerted by the implantable movement restriction device on the stomach wall of the patient.According to one embodiment, the movement restriction device comprises a first portion having a first volume enclosed by material of the implantable movement restriction device and a second portion, different from the first portion, having a second volume enclosed by material of the implantable movement restriction device. The first volume and the second volumes may be equally large and the first volume may have a higher density than the second volume, and the second volume may have a density below 1000 kg / m3.An apparatus for treating reflux disease of a human patient is further provided. The apparatus comprising an implantable movement restriction device having a shape and size allowing it to be arranged to rest against a fundus wall portion of the patient’s stomach, such that the movement restriction device is implanted at a position between the thoracic diaphragm of the patient and a portion of the fundus wall, and such that movement of the lower esophageal sphincter of the patient’s stomach towards the thoracic diaphragm is restricted to hinder the lower esophageal sphincter from sliding through the opening in the thoracic diaphragm into the patient’s thorax. The apparatus further comprising an electrode arrangement configured to engage and electrically stimulate the lower esophageal sphincter for causing contraction of the lower esophageal sphincter. The apparatus further comprising an electric impedance sensor configured to measure a change in electrical impedance in the tissue of the lower esofageal sphincter or in the esophagus tissue for detecting the patient swallowing, and a stimulation controller configured to control the electrical stimulation of the lower esophageal sphincter in response to signals from the electric impedance sensor.According to one embodiment, the apparatus further comprises a reference electrode connected to the stimulation controller, and wherein the stimulation controller is configured to generate the output from the sensor based on an electrical interaction between the electric impedance sensor and the reference electrode. According to one embodiment, the stimulation controller is configured to generate a time-varying signal having a frequency component that varies in the range of 1-10 kHz.According to one embodiment, the stimulation controller is configured to generate a time-varying signal having a frequency component that varies in the range of 2-8 kHz.According to one embodiment, the stimulation controller is configured to generate a time-varying signal having a frequency component that varies in the range of 4-6 kHz.According to one embodiment, the electrode arrangement comprises at least two electrode elements configured to be arranged on opposing sides of the lower esophageal sphincter.According to one embodiment, the apparatus further comprises a holder configured to support the at least two electrode elements at the opposing sides of the cardiac sphincter.According to one embodiment, the apparatus further comprises an implantable energy source configured to provide the electrode with electrical power.According to one embodiment, the implantable energy source is arranged inside the movement restriction device.An implantable medical device for treating obesity is further provided. The implantable medical device is configured to be fixated to the stomach wall and protrude into the stomach and thereby reduce the volume of the cavity of the stomach. The implantable medical device comprises a first part, a second part, and a first distance element. The first and second parts are configured to be connected to each other for forming at least a portion of a functional implantable medical device. The first and second parts are capable of disconnecting from each other, such that the first and second part individually can pass through the gastro-intestinal tract. The first distance element is configured to create a space located between the first and second part. The space is configured to allow in-growth of fibrotic tissue between portions of the first and second parts. The space is confined at least partially by a first surface of the first part and a second surface of the second part. The first and second surfaces are positioned opposite each other when the first and second parts are connected. A line segment of a first straight line is bounded by a first point on the first surface and a second point on the second surface, and the line segment of the first straight line is more than 1mm. A line segment of a second straight line is bounded by a third point on the first surface and a fourth point on the second surface, and the line segment of the second straight line is more than 1mm. The first straight line is parallel to the second straight line, the first and second straight lines intersect a third straight line which also intersects the center of gravity of the functional medical device. A distance between the first and second straight lines is more than 2mm for allowing in-growth of fibrotic tissue for aiding in the fixation of the functional implantable medical device to the stomach wall.The functional implantable medical device may have a volume in the range 100cm3 – 1000cm3, or preferably in the range 100cm3 – 500cm3. The functional implantable medical device may have a length in the range 2,5cm – 15cm, or more preferably a length in the range 5cm – 15cm and even more preferably a length in the range 7cm – 15cm, or even more preferably a length in the range 8cm – 15cm, and even more preferably a length in the range 8cm – 12cm. According to one embodiment, the first distance element is integrated in at least one of the first and second part, and the first distance element may protrude from a surface of at least one of the first and second part.According to one embodiment, the implantable medical device further comprises a first separate distance part comprising the first distance element. According to one embodiment, at least one of the first and second part may further comprise a recess configured to receive a portion of the first distance element.The first distance element may in any of the embodiments herein comprise at least a first and second portion configured to be placed at a distance from each other.According to one embodiment, the implantable medical device further comprises at least a third part, and the first, second and third parts may be configured to be connected to each other for forming at least a portion of the functional movement restriction device.The implantable medical device according to any one of the embodiments herein may further comprise a second distance element, and the first distance element may be configured to create a space between the first and second part and the second distance element may be configured to create a space between the first and third part. The first and second distance element may be portions of a separate distance part. According to one embodiment, at least one of the first, second and third parts may comprise a recess configured to receive a portion of the distance element.According to one embodiment, the space created by the distance element may have a volume exceeding 100mm3.According to one embodiment, the space forms a recess in the implantable medical device, and the recess has a depth exceeding 2mm and a width exceeding 1mm. According to one embodiment, the distance element is configured to prevent at least one of:rotation between the first and second part, linear movement between the first and second part in a first direction, and linear movement between the first and second part in a first and second direction.According to one embodiment, the first separate distance part is configured to be placed centrally in the functional movement restriction device, and the center of gravity of the first separate distance part may substantially coincide with the center of gravity of the functional movement restriction device.According to one embodiment, the first separate distance part comprises at least one rim comprising at least a first and a second surface. The first surface of the rim may be configured to engage a surface of the first part and the second surface of the flange is configured to engage a surface of the second part. The first and second surfaces of the at least one rim may be parallel. The first separate distance part may comprise at least two rims. The first rim may comprise at least a first and a second surface, the first surface of the first rim may be configured to engage a surface of the first part and the second surface of the first rim may be configured to engage a surface of the second part. The second rim may comprise at least a first and a second surface, and the first surface of the second rim may be configured to engage a surface of the first part and the second surface of the second rim may be configured to engage a surface of the third part.According to one embodiment, the first surfaces of the first rim and the first surface of the second rim are angled relative to each other with an angle in the range 20° - 70°. According to one embodiment, the first surfaces of the first rim and the first surface of the second rim are angled relative to each other with an angle in the range 40° - 50°.According to one embodiment, the first surfaces of the first rim and the first surface of the second rim are perpendicular.According to one embodiment, the first distance element may be configured to engage the recess in at least one of the first and second part in a direction of a length axis of the distance element, and the portion of the first distance element configured to enter the recess of the second part may comprise at least one surface being angled relative to the length axis of the distance element. According to one embodiment, the surface of the first distance element being angled may be configured to face a surface of the recess in at least one of the first and second part being angled with an angle different from the angle of the first distance element, and wherein a point on the angled surface of the first distance element is configured to abut a point on the angled surface of the recess.According to one embodiment, the angled surface of the first distance element abuts the angled surface of the recess over a length being less than half of the length of the angled surface of the first distance element.According to one embodiment, the angled surface of the first distance element abuts the angled surface of the recess over a length being less than one third of the length of the angled surface of the first distance element.According to one embodiment, the angled surface of the first distance element abuts the angled surface of the recess over a length being less than half of the depth of the recess, measured in a direction coinciding with the direction of the length axis of the first distance element, when the portion of the first distance element is inserted into the recess. According to one embodiment, the portion of the first distance element configured to enter the recess of the second part comprises a tapered portion. According to one embodiment, the tapered portion is tapered with an angle in the range 20° - 100°. According to one embodiment, the recess in at least one of the first and second part is tapered, such that two surfaces on opposite sides of the tapered portion of the first distance element faces two surfaces on opposite sides of the tapered recess, when the tapered portion of the first distance element is inserted into the recess. The tapered recess may be tapered with an angle in the range 30° - 135°. According to one embodiment, the tapered portion of the first distance element is tapered with a first angle and the tapered recess in at least one of the first and second part is tapered with a second angle, and the second angle is larger than the first angle. The second angle may be more than 3° larger than the first angle, or more than 5° larger than the first angle, or more than 10° larger than the first angle.According to one embodiment, the tapered portion of the first distance element, and the tapered recess in at least one of the first and second part is conical or frustum-conical.According to one embodiment, the tapered portion of the first distance element has the shape of a pyramid with a polygonal base.According to one embodiment, the portion of the first distance element configured to enter the recess of the first or second part comprises at least one surface having a curvature. According to one embodiment, the surface of the first distance element having a curvature is configured to face a surface of the recess in at least one of the first and second part. A point on the surface of the first distance element having the curvature is configured to abut a point on the surface of the recess. According to one embodiment, the surface of the first distance element having a curvature abuts the surface of the recess over a length being less than half of the length of the angled surface of the first distance element, when the first distance element has been positioned in the recess in at least one of the first and second part.According to one embodiment, the surface of the first distance element having a curvature abuts the surface of the recess over a length being less than one third of the length of the angled surface of the first distance element, when the portion of the first distance element is inserted into the recess.According to one embodiment, the surface of the first distance element having a curvature abuts the surface of the recess over a length being less than one third of the length of the angled surface of the first distance element, when the portion of the first distance element is inserted into the recess.According to one embodiment, the surface of the first distance element having a curvature abuts the surface of the recess over a length being less than half of the depth of the recess, measured in a direction coinciding with the direction of the length axis of the first distance element, when the portion of the first distance element is inserted into the recess. According to one embodiment, the portion of the first distance element configured to enter the recess of the second part comprises at least one surface having a first and second curvature extending in perpendicular directions. The portion of the first distance element configured to enter the recess of the second part may comprise at least one spherical surface.According to one embodiment, the recess in at least one of the first and second part is tapered, such that two curved surfaces on opposite sides of the portion of the first distance element configured to enter the recess of the first or second part faces two surfaces on opposite sides of the tapered recess, when the portion of the first distance element configured to enter the recess of the first or second part is inserted into the recess. According to one embodiment, the recess in at least one of the first and second part comprises at least one surface having a curvature. The recess in at least one of the first and second part may comprise at least one surface having a first and second curvature extending in perpendicular directions.According to one embodiment, the recess in at least one of the first and second part comprises at least one spherical surface.According to one embodiment, the portion of the first distance element configured to enter the recess of the first or second part comprises at least one surface having a curvature with a first radius and the recess in at least one of the first and second part comprises at least one surface having a curvature with a second radius. The second radius is according to one embodiment longer than the first radius.According to one embodiment, the portion of the first distance element configured to enter the recess of the first or second part comprises at least one surface having a first and second curvature extending in perpendicular directions. According to one embodiment, the recess in at least one of the first and second part comprises at least one surface having a first and second curvature extending in perpendicular directions, and the sum of the radii of the first and second curvatures of the recess in at least one of the first and second part is longer than the sum of the radii of the first and second curvature of the portion of the first distance element configured to enter the recess.According to one embodiment, the functional implantable medical device or the boundary of the functional implantable medical device may be elongated. The functional implantable medical device may be elongated such that a longest length is more than 1,5 times a widest width. According to one embodiment, the functional implantable medical device comprises a bend, and the functional implantable medical device comprises a bent center axis following the elongation of the functional implantable medical device.According to one embodiment, a first portion of the functional implantable medical device is configured to be positioned such that a first portion of the bent center axis is parallel to the caudal-cranial axis of the patient, and a second portion of the bent center axis is angled relative to the caudal-cranial axis of the patient, with an angle exceeding 5°. According to one embodiment, the second portion of the bent center axis is configured to bepositioned in the stomach such that it is angled towards the esophagus.According to one embodiment, at least one of the first and second part has a shape corresponding to an ellipsoid wedge or a truncated ellipsoid wedge.According to one embodiment, at least one of the first and second part has a shape corresponding to a spherical wedge or a truncated spherical wedge.At least one of the first and second part may have a shape corresponding to a portion of an ellipsoid wedge or a portion of a truncated ellipsoid wedge.According to one embodiment, at least one of the first and second part has a shape corresponding to a hemiellipsoid wedge or a truncated hemiellipsoid wedge.At least one of the first and second part may have a shape corresponding to a portion of a spherical wedge or a portion of a truncated spherical wedge.According to one embodiment, at least one of the first and second part has a shape corresponding to a hemispherical wedge or a truncated hemispherical wedge.According to one embodiment, at least one of the first and second part has a shape corresponding to an ellipsoid segment or a portion of an ellipsoid segment.According to one embodiment, at least one of the first and second part has a shape corresponding to a spherical segment or a portion of a spherical segment.The functional movement restriction device, or the boundary of the functional implantable medical device, may in any of the embodiments have a shape corresponding to an ellipsoid or a truncated ellipsoid.According to one embodiment, the functional implantable medical device, or the boundary of the functional implantable medical device, has a shape corresponding to a sphere or a truncated sphere.According to one embodiment, at least the periphery of at least one of the first and second part has a shape corresponding to a cylinder.According to one embodiment, the combined periphery of the first and second part has a shape corresponding to a cylinder.According to one embodiment, the periphery of the first part has a shape corresponding to a first cylinder having a first radius, and the periphery of the second part has a shape corresponding to a second cylinder having a second radius, and the first and second radii are different.According to one embodiment, the functional implantable medical device, or the boundary of the functional implantable medical device, comprises a stadium shaped cross-section, or a truncated stadium shaped cross-section. According to one embodiment, the functional implantable medical device comprises a bent stadium shaped cross-section, or a truncated bent stadium shaped cross-section. According to one embodiment, a periphery of the first part has a shape corresponding to a cylinder or an ellipsoid segment, and a periphery of the second part has a shape corresponding to a cylinder or an ellipsoid segment, and the first part comprises at least one protrusion protruding from a first base surface and the second part comprises at least one recess in a first base surface, and the at least one protrusion is adapted to be placed at least partially in the at least one recess. The at least one protrusion may be adapted to engage the at least one recess and the first part may further comprise at least one recess in a second base surface.The position of the at least one protrusion may coincide with the position of the at least one recess, such that the recess overlaps the protrusion when the first part is viewed in a direction normal to the first base surface. The at least one recess may recess into the at least one protrusion.According to one embodiment, the at least one protrusion may have the shape of a pyramid with a polygonal base. According to one embodiment, the first part further comprises at least one protrusion in a second base surface, and the second part may further comprise at least one protrusion in a second base surface. The second part may further comprise at least one recess in a second base surface.According to one embodiment, the implantable medical device further comprises a third part, and the first part further comprises a recess in a second base surface, the second part further comprises a protrusion protruding from a second base surface, the third part comprises a protrusion protruding from a first base surface and a recess in a second base surface, the protrusion of the first part is configured to be at least partially inserted into the recess of the second part, the protrusion of the second part is configured to be at least partially inserted into the recess of the third part, and the first, second and third parts are configured to be assembled for forming at least a portion of a functional implantable medical device, and wherein the recesses and protrusions stabilize the parts relative to each other when assembled. According to one embodiment, the area of the first base surface of the first part is smaller than the area of the first base surface of the second part.According to one embodiment, the at least one protrusion protruding from the first base surface of the first part comprises the distance element.The implantable medical device may in any of the embodiments herein comprises a surface friction reducing coating covering at least a part of the surface of the implantable medical device. The surface friction reducing coating may be configured to reduce the friction between the implantable medical device and the tissue of the stomach wall by which the implantable medical device is at least partially invaginated.The implantable medical device may further comprise a sensor configured to sense at least one of a force and a pressure, for monitoring a pressure or force exerted by the implantable medical device on the stomach wall of the patient.According to one embodiment, the implantable medical device comprises a first portion having a first volume enclosed by material of the implantable medical device and a second portion, different from the first portion, having a second volume enclosed by material of the implantable medical device. The first volume and the second volumes may be equally large and the first volume may have a higher density than the second volume, and the second volume may have a density below 1000 kg / m3.An implantable medical device for treating reflux disease is further provided. The implantable medical device comprises a movement restriction device configured to be fixated to the stomach wall for hindering movement of the lower esophageal sphincter relative to the thoracic diaphragm. The movement restriction device comprises a central part, and at least two outer parts. The central part and the at least two outer parts are configured to be connected to each other for forming at least a portion of a functional movement restriction device. The central part and the at least two outer parts are capable of disconnecting from each other, such that the central part and the at least two outer parts individually can pass through the gastro-intestinal tract. The outer surface of the functional movement restriction device comprises at least four flat surfaces separated from each other and interspaced by at least four curved surfaces, and the combined area of the at least four flat surfaces is in the interval 10% - 20% of the total surface area of the functional movement restriction device. According to one embodiment, the functional movement restriction device comprises at least five flat surfaces. According to one embodiment, the outer surface of the functional movement restriction device comprises at least six flat surfaces. According to one embodiment, the outer surface of the functional movement restriction device comprises at least seven flat surfaces. According to one embodiment, the outer surface of the functional movement restriction device comprises at least eight flat surfaces. The flat surfaces in any of the embodiments may be elliptical or circular or polygonal.An implantable medical device for treating reflux disease is further provided. The implantable medical device comprises a movement restriction device configured to be fixated to the stomach wall for hindering movement of the lower esophageal sphincter relative to the thoracic diaphragm. The movement restriction device comprises a central part, and at least two outer parts. The central part and the at least two outer parts are configured to be connected to each other for forming at least a portion of a functional movement restriction device. The central part and the at least two outer parts are capable of disconnecting from each other, such that the central part and the at least two outer parts individually can pass through the gastro-intestinal tract. According to one embodiment, at least one of the functional movement restriction device and the boundary of the functional movement restriction device has a volume in the range 10cm3 – 30cm3 and according to another embodiment, the functional movement restriction device or the boundary of the functional movement restriction device has a volume in the range 12cm3 – 25cm3, and according to another embodiment, the functional movement restriction device or the boundary of the functional movement restriction device has a volume in the range 15cm3 – 25cm3, and according to another embodiment, the functional movement restriction device or the boundary of the functional movement restriction device has a volume in the range 15cm3 – 22cm3.An implantable medical device for treating reflux disease is further provided. The implantable medical device comprises a movement restriction device configured to be fixated to the stomach wall for hindering movement of the lower esophageal sphincter relative to the thoracic diaphragm, the movement restriction device comprises at least two parts, wherein the parts are configured to be connected to each other for forming at least a portion of a functional movement restriction device, and the at least two parts are capable of disconnecting from each other, such that the at least two parts individually can pass through the gastro-intestinal tract. The functional movement restriction device has a height in the range 3cm – 6cm, or a height in the range 3cm – 5cm, or a height in the range 3,5cm – 6cm, or a height in the range 4cm – 6cm.The implantable medical device may further comprise a central part, and the at least two parts may be configured to be connected to the central part for forming at least a portion of the functional movement restriction device. The central part and the at least two parts may be capable of disconnecting from each other, such that the central part and the at least two parts individually can pass through the gastro-intestinal tract.An implantable medical device for treating reflux disease is further provided. The implantable medical device comprises a movement restriction device configured to be fixated to the stomach wall for hindering movement of the lower esophageal sphincter relative to the thoracic diaphragm. The movement restriction device comprises a central part, and at least two outer parts. The central part and the at least two outer parts are configured to be connected to each other for forming at least a portion of a functional movement restriction device. The central part and the at least two outer parts are capable of disconnecting from each other, such that the central part and the at least two outer parts individually can pass through the gastro-intestinal tract. At least one of the two outer parts comprises a wedge-shaped portion and the central part comprises a wedge-shaped portion. The wedge-shaped portion of the at least one outer part is configured to be placed in the wedge-shaped portion of the central part, and the wedge-shaped portion of the at least one outer part is wedge-shaped with a first angle. The wedge-shaped portion of the central part is wedge-shaped with a second angle, and wherein the first angle is more than 7° larger than the second angle. According to one embodiment, the first angle is more than 10° larger than the second angle, and according to another embodiment, the first angle is more than 12° larger than the second angle, and according to another embodiment, the first angle is more than 15° larger than the second angle. The wedge-shaped portion of the at least one outer part may comprise a wedge-shaped recess configured to engage a wedge-shaped protrusion of the central part, or the at least one outer part may comprise a wedge-shaped protrusion configured to engage a wedge-shaped recess of the central part. The wedge-shaped portion of the central part may comprise a wedge-shaped recess or a wedge-shaped protrusion.An implantable medical device for treating reflux disease is further provided. The implantable medical device comprises a movement restriction device configured to be fixated to the stomach wall for hindering movement of the lower esophageal sphincter relative to the thoracic diaphragm. The movement restriction device comprises a central part, and at least two outer parts. The central part and the at least two outer parts are configured to be connected to each other for forming at least a portion of a functional movement restriction device. The central part and the at least two outer parts are capable of disconnecting from each other, such that the central part and the at least two outer parts individually can pass through the gastro-intestinal tract. At least one of the two outer parts comprises a wedge-shaped portion and the central part comprises a wedge-shaped portion. The wedge-shaped portion of the central part is configured to be placed in the wedge-shaped portion of the central part, and the wedge-shaped portion of the at least one outer part is wedge-shaped with a first angle, and the wedge-shaped portion of the central part is wedge-shaped with a second angle, and the second angle is more than 7° larger than the first angle. According to one embodiment, the second angle is more than 10° larger than the first angle, and according to another embodiment, the second angle is more than 12° larger than the first angle, and according to another embodiment, the second angle is more than 15° larger than the first angle.The wedge-shaped portion of the at least one outer part may comprise a wedge-shaped recess or a wedge-shaped protrusion. The wedge-shaped portion of the central part may comprise a wedge-shaped recess or may comprise a wedge-shaped protrusion.An implantable medical device for treating reflux disease is further provided. The implantable medical device comprises a movement restriction device configured to be fixated to the stomach wall for hindering movement of the lower esophageal sphincter relative to the thoracic diaphragm. The movement restriction device comprises a central part, and at least two outer parts. The central part and the at least two outer parts are configured to be connected to each other for forming at least a portion of a functional movement restriction device. The central part and the at least two outer parts are capable of disconnecting from each other, such that the central part and the at least two outer parts individually can pass through the gastro-intestinal tract. At least one of the two outer parts comprises a contacting surface configured to be placed in contact with a contacting surface of the central part, and at least one of the contacting surfaces of the at least one outer part and the contacting surface of the central part is curved.According to one embodiment, the contacting surface of the at least one outer part and the contacting surface of the central part is convex.According to one embodiment, at least one of the contacting surfaces of the at least one outer part and the contacting surface of the central part is concave.According to one embodiment, at least one of the contacting surfaces of the at least one outer part and the contacting surface of the central part comprises an elliptic point.According to one embodiment, the contacting surface of the at least one outer part contacts the contacting surface of the central part over less than half of the area of the contacting surface of the at least one outer part.According to one embodiment, the contacting surface of the at least one outer part contacts the contacting surface of the central part over less than one third of the area of the contacting surface of the at least one outer part.An implantable medical device for treating reflux disease is further provided. The implantable medical device comprises a movement restriction device configured to be fixated to the stomach wall for hindering movement of the lower esophageal sphincter relative to the thoracic diaphragm. The movement restriction device comprises a central part, and at least two outer parts. The central part and the at least two outer parts are configured to be connected to each other for forming at least a portion of a functional movement restriction device. The central part and the at least two outer parts are capable of disconnecting from each other, such that the central part and the at least two outer parts individually can pass through the gastro-intestinal tract. The central part comprises at least three vertically extending rims being spaced apart, and each the at least three vertically extending rims have at least one contacting surface configured to contact at least one surface of the at least two outer parts. At least a portion of the at least three vertically extending rims is wedge-shaped with an angle in the range 20° - 60°.According to one embodiment, a portion of the at least three vertically extending rims is wedge-shaped with an angle exceeding 25°.According to one embodiment, a portion of the at least three vertically extending rims is wedge-shaped with an angle exceeding 30°.According to one embodiment, a portion of the at least three vertically extending rims is wedge-shaped with an angle exceeding 35°.The wedge-shaped portion of the at least one vertically extending rim may be tapered in a direction away from the center of gravity of the central part. According to one embodiment, the vertically extending rim has an elongated wedge-shaped portion, and wherein the elongated wedge-shaped portion of the vertically extending rim is tapered in a direction of the elongation of the vertically extending rim.The implantable medical device may further comprise at least one horizontally extending rim extending substantially perpendicularly from at least one of the vertically extending rims, and the horizontally extending rim may comprise a wedge-shaped portion. The wedge-shaped portion of the horizontally extending rim may be tapered in a direction away from the center of gravity of the central part.According to one embodiment, the wedge-shaped portion of the horizontally extending rim is wedge-shaped with an angle in the range 20° - 60°.An implantable medical device for treating reflux disease is further provided. The implantable medical device comprises a movement restriction device configured to be fixated to the stomach wall for hindering movement of the lower esophageal sphincter relative to the thoracic diaphragm. The movement restriction device comprises a central part, and at least two outer parts. The central part and the at least two outer parts are configured to be connected to each other for forming at least a portion of a functional movement restriction device. The central part and the at least two outer parts are capable of disconnecting from each other, such that the central part and the at least two outer parts individually can pass through the gastro-intestinal tract. The central part comprises at least one horizontally extending rim extending in a direction perpendicular to the vertical plane and wherein the central part has at least one contacting surface configured to contact at least one surface of the at least two outer parts. A portion of the horizontally extending rim is wedge-shaped with an angle in the range 20° - 60°.According to one embodiment, a portion of the horizontally extending rim is wedge-shaped with an angle exceeding 25°, or with an angle exceeding 30°, or with an angle exceeding 35°.According to one embodiment, the wedge-shaped portion of the horizontally extending rim is tapered in a direction away from the center of gravity of the central part.According to one embodiment, the implantable medical device further comprises at least two vertically extending rims extending substantially perpendicularly from the horizontally extending rim. According to one embodiment, the vertically extending rims comprises wedge-shaped portions. According to one embodiment, the wedge-shaped portion of the vertically extending rims are tapered in a direction away from the center of gravity of the central part.According to one embodiment, the wedge-shaped portions of the vertically extending rims are wedge-shaped with an angle in the range 20° - 60°.An implantable medical device for treating reflux disease is further provided. The implantable medical device comprises a movement restriction device configured to be fixated to the stomach wall for hindering movement of the lower esophageal sphincter relative to the thoracic diaphragm. The movement restriction device comprises a central part, and at least two outer parts. The central part and the at least two outer parts are configured to be connected to each other for forming at least a portion of a functional movement restriction device. The central part and the at least two outer parts are capable of disconnecting from each other, such that the central part and the at least two outer parts individually can pass through the gastro-intestinal tract. The mass of the central part exceeds the mass of at least one of the outer parts. According to one embodiment, the mass of the central part exceeds the mass of at least one of the outer parts by at least 10%.According to one embodiment, the mass of the central part exceeds the mass of at least one of the outer parts by at least 20%.According to one embodiment, the mass of the central part exceeds the mass of at least one of the outer parts by at least 30%.According to one embodiment, the volume of the central part exceeds the volume of at least one of the outer parts by at least 10%. According to one embodiment, the volume of the central part exceeds the volume of at least one of the outer parts by at least 20%.According to one embodiment, the volume of the central part exceeds the volume of at least one of the outer parts by at least 30%.An implantable medical device for treating reflux disease is further provided. The implantable medical device comprises a movement restriction device configured to be fixated to the stomach wall for hindering movement of the lower esophageal sphincter relative to the thoracic diaphragm. The movement restriction device comprises a central part, and at least two outer parts. The central part and the at least two outer parts are configured to be connected to each other for forming at least a portion of a functional movement restriction device. The central part and the at least two outer parts are capable of disconnecting from each other, such that the central part and the at least two outer parts individually can pass through the gastro-intestinal tract. The longest cross-sectional distance of at least one of the outer parts exceeds the longest cross-sectional distance of the central part by at least 20%.According to one embodiment, the longest cross-sectional distance of at least one of the outer parts exceeds the longest cross-sectional distance of the central part by at least 30%.According to one embodiment, the longest cross-sectional distance of at least one of the outer parts exceeds the longest cross-sectional distance of the central part by at least 40%.According to one embodiment, the longest cross-sectional distance of at least one of the outer parts exceeds the longest cross-sectional distance of the central part by at least 50%.An implantable medical device for treating reflux disease is further provided, the implantable medical device comprises a movement restriction device configured to be fixated to the stomach wall for hindering movement of the lower esophageal sphincter relative to the thoracic diaphragm. According to one embodiment, at least one of the movement restriction device and the boundary of the movement restriction device has a surface area in the range 20cm2 – 50cm2.According to one embodiment, at least one of the movement restriction device and the boundary of the movement restriction device has a surface area in the range 25cm2 – 50cm2.According to one embodiment, at least one of the movement restriction device and the boundary of the movement restriction device has a surface area in the range 25cm2 – 40cm2.According to one embodiment, at least one of the movement restriction device and the boundary of the movement restriction device has a surface area in the range 20cm2 – 40cm2.According to one embodiment, at least one of the movement restriction device and the boundary of the movement restriction device has a surface area in the range 20cm2 – 35cm2.According to one embodiment, at least one of the movement restriction device and the boundary of the movement restriction device has a surface area in the range 20cm2 – 30cm2.According to one embodiment, the movement restriction device is elongated and has a height, being a longest cross-sectional distance, and a width, being a longest cross-sectional distance perpendicular to the height, and wherein the height is in the range 1,2 times – 2 times longer than the width. According to one embodiment, the height is in the range 1,3 times – 2 times longer than the width. According to one embodiment, the height is in the range 1,2 times – 1,8 times longer than the width. According to one embodiment, the height is in the range 1,3 times – 1,6 times longer than the width.According to one embodiment, the movement restriction device has a height in the range 3cm – 5cm, or a height in the range 3,5cm – 6cm, or a height in the range 4cm – 5cm, or a height in the range 4cm – 6cm.According to one embodiment, at least one of the movement restriction device and the boundary of the movement restriction device has a volume in the range 10cm3 – 30cm3 and according to another embodiment, the movement restriction device or the boundary of the movement restriction device has a volume in the range 12cm3 – 25cm3, and according to another embodiment, the movement restriction device or the boundary of the movement restriction device has a volume in the range 15cm3 – 25cm3, and according to another embodiment, the movement restriction device or the boundary of the movement restriction device has a volume in the range 15cm3 – 22cm3.An implantable medical device for treating reflux disease is further provided, the implantable medical device comprises a movement restriction device configured to be fixated to the stomach wall for hindering movement of the lower esophageal sphincter relative to the thoracic diaphragm, the movement restriction device comprises at least two parts, wherein the parts are configured to be connected to each other for forming at least a portion of a functional movement restriction device, and the at least two parts are capable of disconnecting from each other, such that the at least two parts individually can pass through the gastro-intestinal tract. At least one of the functional movement restriction device and the boundary of the functional movement restriction device has a surface area in the range 20cm2 – 50cm2.According to one embodiment, at least one of the functional movement restriction device and the boundary of the functional movement restriction device has a surface area in the range 25cm2 – 50cm2.According to one embodiment, at least one of the functional movement restriction device and the boundary of the functional movement restriction device has a surface area in the range 25cm2 – 40cm2.According to one embodiment, at least one of the functional movement restriction device and the boundary of the functional movement restriction device has a surface area in the range 20cm2 – 40cm2.According to one embodiment, at least one of the functional movement restriction device and the boundary of the functional movement restriction device has a surface area in the range 20cm2 – 35cm2.According to one embodiment, at least one of the functional movement restriction device and the boundary of the functional movement restriction device has a surface area in the range 20cm2 – 30cm2.According to one embodiment, the functional movement restriction device is elongated and has a height, being a longest cross-sectional distance, and a width, being a longest cross-sectional distance perpendicular to the height, and wherein the height is in the range 1,2 times – 2 times longer than the width. According to one embodiment, the height is in the range 1,3 times – 2 times longer than the width. According to one embodiment, the height is in the range 1,2 times – 1,8 times longer than the width. According to one embodiment, the height is in the range 1,3 times – 1,6 times longer than the width.According to one embodiment, the functional movement restriction device has a height in the range 3cm – 5cm, or a height in the range 3,5cm – 6cm, or a height in the range 4cm – 5cm, or a height in the range 4cm – 6cm.According to one embodiment, the implantable medical device further comprises a central part, and the at least two parts are configured to be connected to the central part for forming at least a portion of the functional movement restriction device. The central part and the at least two parts are capable of disconnecting from each other, such that the central part and the at least two parts individually can pass through the gastro-intestinal tract.An implantable medical device for treating reflux disease is further provided. The implantable medical device comprises a movement restriction device configured to be fixated to the stomach wall for hindering movement of the lower esophageal sphincter relative to the thoracic diaphragm. The movement restriction device comprises at least two parts, wherein the parts are configured to be connected to each other for forming at least a portion of a functional movement restriction device. The at least two parts are capable of disconnecting from each other, such that the at least two parts individually can pass through the gastro-intestinal tract. The functional movement restriction device is elongated and has a height, being a longest cross-sectional distance, and a width, being a longest cross-sectional distance perpendicular to the height, and wherein the height is the range 1,2 – 2 times longer than the width. According to one embodiment, the height is in the range 1,3 – 2 times longer than the width. According to one embodiment, the height is in the range 1,2 – 1,8 times longer than the width. According to one embodiment, the height is in the range 1,3 – 1,6 times longer than the width.According to one embodiment, the functional movement restriction device has a height in the range 3cm – 5cm.According to one embodiment, the functional movement restriction device has a height in the range 3,5cm – 6cm.According to one embodiment, the functional movement restriction device has a height in the range 4cm – 5cm.According to one embodiment, the functional movement restriction device has a height in the range 4cm – 6cm.The implantable medical device may further comprise a central part, and the at least two parts may be configured to be connected to the central part for forming at least a portion of the functional movement restriction device. The central part and the at least two parts may be capable of disconnecting from each other, such that the central part and the at least two parts individually can pass through the gastro-intestinal tract.A surgical method of treating reflux disease is further provided. The surgical method comprises steps of dissecting the fundus at least partially on the posterior side thereof, dissecting the esophagus such that the esophagus is disconnected from the surrounding tissue at least 3cm in a cranial direction from the angle of his, connecting the fundus to the esophagus by: placing at least two posterior sutures or staplers, connecting the fundus to the esophagus, on the sinister-posterior side of the esophagus, and placing at least two anterior sutures or staplers, connecting the fundus to the esophagus, on the sinister-anterior side of the esophagus. The surgical method further comprises the step of fixating an implantable movement restriction device to the fundus, such that the lower esophageal sphincter is prevented from sliding through the esophageal hiatus. According to one embodiment the surgical method step of dissecting the fundus at least partially on the posterior side thereof comprises at least partially freeing the fundus from at least one of the gastrophrenic ligament and the gastrosplenic ligament. The step of dissecting the fundus at least partially on the posterior side thereof may comprise dissecting the fundus at least 0,5 cm posterior to a coronal plane intersecting a most cranial point of the fundus, or dissecting the fundus at least partially on the posterior side thereof at least 1 cm posterior to a coronal plane intersecting a most cranial point of the fundus.According to one embodiment the surgical method step of dissecting the fundus at least partially on the posterior side thereof may comprise dissecting the fundus at least 0,5 cm posterior to the most anterior fixation point of the gastrophrenic ligament on the fundus, or at least 1 cm posterior to the most anterior fixation point of the gastrophrenic ligament on the fundus.According to one embodiment the surgical method step of dissecting the fundus at least partially on the posterior side thereof comprises dissecting the fundus at least 0,5 cm posterior to an extension of the greater curvature of the stomach in the region of the fundus, or at least 1 cm posterior to an extension of the greater curvature of the stomach in the region of the fundus.According to one embodiment the surgical method step of dissecting the esophagus comprises dissecting the esophagus such that the esophagus is disconnected from the surrounding tissue at least 4 cm in a cranial direction from the angle of his, preferably at least 5 cm in a cranial direction from the angle of his and most preferably at least 6 cm in a cranial direction from the angle of his.According to one embodiment the surgical method step of dissecting the esophagus such that the esophagus is disconnected from the surrounding tissue comprises dissecting the esophagus into mediastinum. The step of dissecting the esophagus into mediastinum may comprise dissecting the esophagus into mediastinum such that the esophagus is disconnected from the surrounding tissue at least 1 cm in a cranial direction from the distal edge of the esophageal hiatus, preferably at least 2 cm in a cranial direction from the distal edge of the esophageal hiatus and most preferably at least 3 cm in a cranial direction from the distal edge of the esophageal hiatus.According to one embodiment, the step of dissecting the esophagus into mediastinum comprises dissecting the esophagus distally from a point 2 cm distally from the esophageal plexus of the vagus nerve, preferably from a point 1 cm distally from the esophageal plexus of the vagus nerve, more preferably from a point 0,5 cm distally from the esophageal plexus of the vagus nerve.According to one embodiment, the step of dissecting the esophagus comprises freeing the esophagus from the crus muscles. According to one embodiment, the surgical method step of placing at least two posterior sutures or staplers, connecting the fundus to the esophagus, on the sinister-posterior side of the esophagus, comprises placing at least two continuous sutures connecting the fundus to the esophagus, on the sinister-posterior side of the esophagus. According to one embodiment, the surgical method step of placing at least two anterior sutures or staplers, connecting the fundus to the esophagus, on the sinister-anterior side of the esophagus comprises placing at least two continuous sutures connecting the fundus to the esophagus, on the sinister-anterior side of the esophagus.In any of the embodiments herein, at least one of starting and ending of the continuous sutures may be performed in the serosa of the stomach wall for securing the sutures to the serosa of the stomach wall.According to one embodiment, the surgical method step of placing at least two posterior sutures or staplers, connecting the fundus to the esophagus, on the sinister-posterior side of the esophagus comprises placing at least two lateral sutures substantially along a cranial-caudal axis, on the sinister-posterior side of the esophagus.According to one embodiment, the surgical method step of placing at least two anterior sutures or staplers, connecting the fundus to the esophagus, on the sinister-anterior side of the esophagus comprises placing at least two lateral sutures substantially along a cranial-caudal axis, on the sinister-anterior side of the esophagus.According to one embodiment, the surgical method step of placing at least two posterior sutures or staplers, connecting the fundus to the esophagus, on the sinister-posterior side of the esophagus, comprises placing the at least two posterior sutures or staplers at least 0,5 cm posterior to a coronal plane intersecting a most cranial point of the fundus.According to one embodiment the surgical method step of placing at least two anterior sutures or staplers, connecting the fundus to the esophagus, on the sinister-anterior side of the esophagus, comprises placing the at least two anterior sutures or staplers at least 0,5 cm anterior from the coronal plane intersecting the most cranial point of the fundus.According to one embodiment, the surgical method step of placing at least two posterior sutures or staplers, connecting the fundus to the esophagus, on the sinister-posterior side of the esophagus comprises placing the most caudal suture or stapler at least 0,5 cm from the angle of His. According to one embodiment the surgical method step of placing at least two anterior sutures or staplers, connecting the fundus to the esophagus, on the sinister-anterior side of the esophagus comprises placing the most caudal suture or stapler at least 0,5 cm from the angle of His.According to one embodiment the surgical method step of placing at least two posterior sutures or staplers, connecting the fundus to the esophagus, on the sinister-posterior side of the esophagus comprises placing the most caudal suture or stapler at least 1,5 cm from the angle of His.According to one embodiment the surgical method step of placing at least two anterior sutures or staplers, connecting the fundus to the esophagus, on the sinister-anterior side of the esophagus comprises placing the most caudal suture or stapler at least 1,5 cm from the angle of His.According to one embodiment the surgical method step of placing the most caudal suture or stapler of the at least two posterior sutures or staplers, connecting the fundus to the esophagus, on the sinister-posterior side of the esophagus at least 0,5 cm from the angle of His and placing the most caudal suture or stapler of the at least two anterior sutures or staplers, connecting the fundus to the esophagus, on the sinister-anterior side of the esophagus at least 1,5 cm from the angle of His.According to one embodiment the surgical method step of placing the most caudal suture or stapler of the at least two posterior sutures or staplers, connecting the fundus to the esophagus, on the sinister-posterior side of the esophagus at least 1,5 cm from the angle of His and placing the most caudal suture or stapler of the at least two anterior sutures or staplers, connecting the fundus to the esophagus, on the sinister-anterior side of the esophagus at least 0,5 cm from the angle of His.According to one embodiment the surgical method step of connecting the fundus to the esophagus further comprises placing at least one central suture or stapler on a cranial-caudal axis extending between the at least two posterior sutures or staplers and the at least two anterior sutures or staplers. The step of placing at least one central suture or stapler on a cranial-caudal axis may comprise placing at least one central suture or stapler being disconnected from the at least two anterior sutures or staplers and from the at least two posterior sutures or staplers, for maintaining the possibility of radial expansion the esophagus for limiting the disk of dysphagia.According to one embodiment the surgical method step of placing at least two posterior sutures or staplers, connecting the fundus to the esophagus, on the sinister-posterior side of the esophagus, and placing at least two anterior sutures or staplers, connecting the fundus to the esophagus, on the sinister-anterior side of the esophagus, comprises using an at least partially barbed suture. In any of the surgical methods described herein, the step of fixating the implantable movement restriction device to the fundus may comprise placing continuous purse-string roof sutures in the region of the greater curvature of the stomach, in the region of the fundus, such that the stomach tissue can be contracted by pulling the ends of the purse-string sutures. The step of placing roof sutures may comprise placing at least one of the continuous purse-string roof sutures at least 1 cm behind the greater curvature of the stomach, in the region of the fundus.According to one embodiment the step of placing the continuous purse-string roof sutures may comprise placing the continuous purse-string roof sutures using an at least partially un-barbed suture.According to one embodiment the surgical method step of placing the continuous purse-string roof sutures may comprise starting or ending the continuous purse-string roof sutures at least 0,5 cm from the esophagus. According to one embodiment, the surgical method step of placing the continuous purse-string roof sutures may comprise placing the continuous purse-string roof sutures using a suture ending with a loop, such that the suture can be drawn through the loop for contracting the stomach tissue. In any of the surgical methods described herein, the step of fixating the implantable movement restriction device to the fundus may comprise inserting the implantable movement restriction device into the abdomen of the patient. The step of inserting the implantable movement restriction device into the abdomen of the patient may comprise inserting the implantable movement restriction device into the abdomen of the patient using an insertion instrument having an elongated abdominal portion.According to one embodiment, the surgical method step of fixating the implantable movement restriction device to the fundus may comprise pushing the implantable movement restriction device into the fundus in a cranial-dorsal direction using the instrument having the elongated abdominal portion. The step of pushing the implantable movement restriction device into the fundus in a dorsal-cranial direction using the instrument having the elongated abdominal portion may comprise pushing the implantable movement restriction device into the fundus in a dorsal-cranial direction using the instrument such that a portion of the implantable medical device ends up dorsal to the roof sutures for placing the movement restriction device in the fundus for facilitating the subsequent invagination in a high-up in fundus position. According to one embodiment, the step of fixating the implantable movement restriction device to the fundus comprises placing continuous purse-string base sutures in the region of the caudal end of the implantable movement restriction device. The step of placing continuous purse-string floor sutures in the region of the caudal end of the implantable movement restriction device may comprise placing at least two of the continuous purse-string floor sutures following an arc. In cases when the at least two continuous purse-string floor sutures are placed following an arc the continuous purse-string floor sutures may be placed following an arc below the elongated abdominal portion of the instrument holding the implantable movement restriction device.According to one embodiment, the step of placing continuous purse-string base sutures in the region of the caudal end of the implantable movement restriction device may comprise placing the continuous purse-string base sutures such that the continuous purse-string base sutures forms a closed curve.According to one embodiment, the step of fixating the implantable movement restriction device to the fundus may comprise placing at least one suture or stapler from stomach wall to stomach wall above the elongated abdominal portion of the instrument holding the implantable movement restriction device.According to one embodiment, the step of placing continuous purse-string base sutures in the region of the caudal end of the implantable movement restriction device may comprise placing one of the continuous purse-string base sutures from stomach wall to stomach wall above the elongated abdominal portion of the instrument holding the implantable movement restriction device.The step of fixating the implantable movement restriction device to the fundus may comprise releasing the elongated abdominal portion of the instrument from the implantable movement restriction device.According to one embodiment, the step of fixating the implantable movement restriction device to the fundus may comprise placing at least one suture or stapler from stomach wall to stomach wall in the region from which the elongated abdominal portion of the instrument was removed, for closing the hole through which the elongated abdominal portion of the instrument passed. According to one embodiment, the step of placing continuous purse-string base sutures in the region of the caudal end of the implantable movement restriction device may comprise placing continuous purse-string base sutures using an at least un-barbed suture for enabling the contraction and relaxation of the stomach wall during the surgical procedure. According to one embodiment, the step of fixating the implantable movement restriction device to the fundus comprises contracting a first portion of the stomach wall by pulling on the purse-string roof sutures and contracting a second portion of the stomach wall by pulling on the purse-string base sutures. The implantable movement restriction device may thus be fixated in the stomach wall between the first contracted portion and the second contracted portion. The surgical method according to any one of the preceding embodiments may further comprise the step of fixating the implantable movement restriction device to the fundus by invaginating the implantable movement restriction device in the fundus wall from the outside thereof. The step of invaginating the implantable movement restriction device in the fundus wall from the outside thereof may comprise placing at least two sutures or staplers from stomach wall to stomach wall for connecting stomach wall to stomach wall around the implantable movement restriction device and thereby enclose the implantable movement restriction device in a pouch formed by the stomach wall of the fundus. The step of invaginating the implantable movement restriction device may comprise ending the invagination by fixating the suture to the serosa of the stomach wall for long term fixation.According to one embodiment, the step of fixating the implantable movement restriction device to the fundus comprises contracting the first portion of the stomach wall by pulling on the purse-string roof sutures and determining the length of the loop formed by the purse-string roof sutures by securing the purse-string roof sutures to the serosa of the stomach wall. A surgical method of treating reflux disease is further provided. The surgical method comprises the steps of connecting the fundus to the esophagus by: placing at least two posterior lateral sutures or staplers substantially along a cranial-caudal axis on the sinister-posterior side of the esophagus, connecting the fundus to the esophagus on the sinister-posterior side of the esophagus, and placing at least two anterior lateral sutures or staplers substantially along a cranial-caudal axis on the sinister-posterior side of the esophagus, connecting the fundus to the esophagus on the sinister-posterior side of the esophagus. The surgical method further comprises the step of fixating an implantable movement restriction device to the fundus, such that the lower esophageal sphincter is prevented from sliding through the esophageal hiatus. According to one embodiment, the surgical method step of placing at least two posterior sutures or staplers, connecting the fundus to the esophagus, on the sinister-posterior side of the esophagus, comprises placing at least two continuous sutures connecting the fundus to the esophagus, on the sinister-posterior side of the esophagus. According to one embodiment, the surgical method step of placing at least two anterior sutures or staplers, connecting the fundus to the esophagus, on the sinister-anterior side of the esophagus comprises placing at least two continuous sutures connecting the fundus to the esophagus, on the sinister-anterior side of the esophagus.In any of the embodiments herein, at least one of starting and ending of the continuous sutures may be performed in the serosa of the stomach wall for securing the sutures to the serosa of the stomach wall.According to one embodiment, the surgical method step of placing at least two posterior sutures or staplers, connecting the fundus to the esophagus, on the sinister-posterior side of the esophagus comprises placing at least two lateral sutures substantially along a cranial-caudal axis, on the sinister-posterior side of the esophagus.According to one embodiment, the surgical method step of placing at least two anterior sutures or staplers, connecting the fundus to the esophagus, on the sinister-anterior side of the esophagus comprises placing at least two lateral sutures substantially along a cranial-caudal axis, on the sinister-anterior side of the esophagus.According to one embodiment, the surgical method step of placing at least two posterior sutures or staplers, connecting the fundus to the esophagus, on the sinister-posterior side of the esophagus, comprises placing the at least two posterior sutures or staplers at least 0,5 cm posterior to a coronal plane intersecting a most cranial point of the fundus.According to one embodiment the surgical method step of placing at least two anterior sutures or staplers, connecting the fundus to the esophagus, on the sinister-anterior side of the esophagus, comprises placing the at least two anterior sutures or staplers at least 0,5 cm anterior from the coronal plane intersecting the most cranial point of the fundus.According to one embodiment, the surgical method step of placing at least two posterior sutures or staplers, connecting the fundus to the esophagus, on the sinister-posterior side of the esophagus comprises placing the most caudal suture or stapler at least 0,5 cm from the angle of His. According to one embodiment the surgical method step of placing at least two anterior sutures or staplers, connecting the fundus to the esophagus, on the sinister-anterior side of the esophagus comprises placing the most caudal suture or stapler at least 0,5 cm from the angle of His.According to one embodiment the surgical method step of placing at least two posterior sutures or staplers, connecting the fundus to the esophagus, on the sinister-posterior side of the esophagus comprises placing the most caudal suture or stapler at least 1,5 cm from the angle of His.According to one embodiment the surgical method step of placing at least two anterior sutures or staplers, connecting the fundus to the esophagus, on the sinister-anterior side of the esophagus comprises placing the most caudal suture or stapler at least 1,5 cm from the angle of His.According to one embodiment the surgical method step of placing the most caudal suture or stapler of the at least two posterior sutures or staplers, connecting the fundus to the esophagus, on the sinister-posterior side of the esophagus at least 0,5 cm from the angle of His and placing the most caudal suture or stapler of the at least two anterior sutures or staplers, connecting the fundus to the esophagus, on the sinister-anterior side of the esophagus at least 1,5 cm from the angle of His.According to one embodiment the surgical method step of placing the most caudal suture or stapler of the at least two posterior sutures or staplers, connecting the fundus to the esophagus, on the sinister-posterior side of the esophagus at least 1,5 cm from the angle of His and placing the most caudal suture or stapler of the at least two anterior sutures or staplers, connecting the fundus to the esophagus, on the sinister-anterior side of the esophagus at least 0,5 cm from the angle of His.According to one embodiment the surgical method step of connecting the fundus to the esophagus further comprises placing at least one central suture or stapler on a cranial-caudal axis extending between the at least two posterior sutures or staplers and the at least two anterior sutures or staplers. The step of placing at least one central suture or stapler on a cranial-caudal axis may comprise placing at least one central suture or stapler being disconnected from the at least two anterior sutures or staplers and from the at least two posterior sutures or staplers, for maintaining the possibility of radial expansion the esophagus for limiting the disk of dysphagia.According to one embodiment the surgical method step of placing at least two posterior sutures or staplers, connecting the fundus to the esophagus, on the sinister-posterior side of the esophagus, and placing at least two anterior sutures or staplers, connecting the fundus to the esophagus, on the sinister-anterior side of the esophagus, comprises using an at least partially barbed suture. A surgical method of treating reflux disease is further provided. The surgical method comprises the steps of dissecting the fundus at least partially on the posterior side thereof, wherein the step of dissecting the fundus at least partially on the posterior side thereof comprises at least partially freeing the fundus from at least one of the gastrophrenic ligament and the gastrosplenic ligament, and fixating an implantable movement restriction device to the fundus, such that the lower esophageal sphincter is prevented from sliding through the esophageal hiatus.The step of dissecting the fundus at least partially on the posterior side thereof may comprise dissecting the fundus at least 0,5 cm posterior to a coronal plane intersecting a most cranial point of the fundus or dissecting the fundus at least partially on the posterior side thereof at least 1 cm posterior to a coronal plane intersecting a most cranial point of the fundus.According to one embodiment the surgical method step of dissecting the fundus at least partially on the posterior side thereof may comprise dissecting the fundus at least 0,5 cm posterior to the most anterior fixation point of the gastrophrenic ligament on the fundus, or at least 1 cm posterior to the most anterior fixation point of the gastrophrenic ligament on the fundus.According to one embodiment the surgical method step of dissecting the fundus at least partially on the posterior side thereof comprises dissecting the fundus at least 0,5 cm posterior to an extension of the greater curvature of the stomach in the region of the fundus, or at least 1 cm posterior to an extension of the greater curvature of the stomach in the region of the fundus.In any of the surgical methods described herein, the step of fixating the implantable movement restriction device to the fundus may comprise placing continuous purse-string roof sutures in the region of the greater curvature of the stomach, in the region of the fundus, such that the stomach tissue can be contracted by pulling the ends of the purse-string sutures. The step of placing roof sutures may comprise placing at least one of the continuous purse-string roof sutures at least 1 cm behind the greater curvature of the stomach, in the region of the fundus.According to one embodiment the step of placing the continuous purse-string roof sutures may comprise placing the continuous purse-string roof sutures using an at least partially un-barbed suture.According to one embodiment the surgical method step of placing the continuous purse-string roof sutures may comprise starting or ending the continuous purse-string roof sutures at least 0,5 cm from the esophagus. According to one embodiment, the surgical method step of placing the continuous purse-string roof sutures may comprise placing the continuous purse-string roof sutures using a suture ending with a loop, such that the suture can be drawn through the loop for contracting the stomach tissue. In any of the surgical methods described herein, the step of fixating the implantable movement restriction device to the fundus may comprise inserting the implantable movement restriction device into the abdomen of the patient. The step of inserting the implantable movement restriction device into the abdomen of the patient may comprise inserting the implantable movement restriction device into the abdomen of the patient using an insertion instrument having an elongated abdominal portion.According to one embodiment, the surgical method step of fixating the implantable movement restriction device to the fundus may comprise pushing the implantable movement restriction device into the fundus in a cranial-dorsal direction using the instrument having the elongated abdominal portion. The step of pushing the implantable movement restriction device into the fundus in a dorsal-cranial direction using the instrument having the elongated abdominal portion may comprise pushing the implantable movement restriction device into the fundus in a dorsal-cranial direction using the instrument such that a portion of the implantable medical device ends up dorsal to the roof sutures for placing the movement restriction device in the fundus for facilitating the subsequent invagination in a high-up in fundus position. According to one embodiment, the step of fixating the implantable movement restriction device to the fundus comprises placing continuous purse-string base sutures in the region of the caudal end of the implantable movement restriction device. The step of placing continuous purse-string floor sutures in the region of the caudal end of the implantable movement restriction device may comprise placing at least two of the continuous purse-string floor sutures following an arc. In cases when the at least two continuous purse-string floor sutures are placed following an arc the continuous purse-string floor sutures may be placed following an arc below the elongated abdominal portion of the instrument holding the implantable movement restriction device.According to one embodiment, the step of placing continuous purse-string base sutures in the region of the caudal end of the implantable movement restriction device may comprise placing the continuous purse-string base sutures such that the continuous purse-string base sutures forms a closed curve.According to one embodiment, the step of fixating the implantable movement restriction device to the fundus may comprise placing at least one suture or stapler from stomach wall to stomach wall above the elongated abdominal portion of the instrument holding the implantable movement restriction device.According to one embodiment, the step of placing continuous purse-string base sutures in the region of the caudal end of the implantable movement restriction device may comprise placing one of the continuous purse-string base sutures from stomach wall to stomach wall above the elongated abdominal portion of the instrument holding the implantable movement restriction device.The step of fixating the implantable movement restriction device to the fundus may comprise releasing the elongated abdominal portion of the instrument from the implantable movement restriction device.According to one embodiment, the step of fixating the implantable movement restriction device to the fundus may comprise placing at least one suture or stapler from stomach wall to stomach wall in the region from which the elongated abdominal portion of the instrument was removed, for closing the hole through which the elongated abdominal portion of the instrument passed. According to one embodiment, the step of placing continuous purse-string base sutures in the region of the caudal end of the implantable movement restriction device may comprise placing continuous purse-string base sutures using an at least un-barbed suture for enabling the contraction and relaxation of the stomach wall during the surgical procedure. According to one embodiment, the step of fixating the implantable movement restriction device to the fundus comprises contracting a first portion of the stomach wall by pulling on the purse-string roof sutures and contracting a second portion of the stomach wall by pulling on the purse-string base sutures. The implantable movement restriction device may thus be fixated in the stomach wall between the first contracted portion and the second contracted portion. The surgical method according to any one of the preceding embodiments may further comprise the step of fixating the implantable movement restriction device to the fundus by invaginating the implantable movement restriction device in the fundus wall from the outside thereof. The step of invaginating the implantable movement restriction device in the fundus wall from the outside thereof may comprise placing at least two sutures or staplers from stomach wall to stomach wall for connecting stomach wall to stomach wall around the implantable movement restriction device and thereby enclose the implantable movement restriction device in a pouch formed by the stomach wall of the fundus. The step of invaginating the implantable movement restriction device may comprise ending the invagination by fixating the suture to the serosa of the stomach wall for long term fixation.According to one embodiment, the step of fixating the implantable movement restriction device to the fundus comprises contracting the first portion of the stomach wall by pulling on the purse-string roof sutures and determining the length of the loop formed by the purse-string roof sutures by securing the purse-string roof sutures to the serosa of the stomach wall. A surgical method of treating reflux disease is further provided. The surgical method comprises the steps of: dissecting the esophagus such that the esophagus is disconnected from the surrounding tissue at least 3cm in a cranial direction from the angle of his and fixating an implantable movement restriction device to the fundus, such that the lower esophageal sphincter is prevented from sliding through the esophageal hiatus. According to one embodiment the surgical method step of dissecting the esophagus comprises dissecting the esophagus such that the esophagus is disconnected from the surrounding tissue at least 4 cm in a cranial direction from the angle of his, preferably at least 5 cm in a cranial direction from the angle of his and most preferably at least 6 cm in a cranial direction from the angle of his.According to one embodiment the surgical method step of dissecting the esophagus such that the esophagus is disconnected from the surrounding tissue comprises dissecting the esophagus into mediastinum. The step of dissecting the esophagus into mediastinum may comprise dissecting the esophagus into mediastinum such that the esophagus is disconnected from the surrounding tissue at least 1 cm in a cranial direction from the distal edge of the esophageal hiatus, preferably at least 2 cm in a cranial direction from the distal edge of the esophageal hiatus and most preferably at least 3 cm in a cranial direction from the distal edge of the esophageal hiatus.According to one embodiment, the surgical method step of placing at least two posterior sutures or staplers, connecting the fundus to the esophagus, on the sinister-posterior side of the esophagus, comprises placing at least two continuous sutures connecting the fundus to the esophagus, on the sinister-posterior side of the esophagus. According to one embodiment, the surgical method step of placing at least two anterior sutures or staplers, connecting the fundus to the esophagus, on the sinister-anterior side of the esophagus comprises placing at least two continuous sutures connecting the fundus to the esophagus, on the sinister-anterior side of the esophagus.In any of the embodiments herein, at least one of starting and ending of the continuous sutures may be performed in the serosa of the stomach wall for securing the sutures to the serosa of the stomach wall.According to one embodiment, the surgical method step of placing at least two posterior sutures or staplers, connecting the fundus to the esophagus, on the sinister-posterior side of the esophagus comprises placing at least two lateral sutures substantially along a cranial-caudal axis, on the sinister-posterior side of the esophagus.According to one embodiment, the surgical method step of placing at least two anterior sutures or staplers, connecting the fundus to the esophagus, on the sinister-anterior side of the esophagus comprises placing at least two lateral sutures substantially along a cranial-caudal axis, on the sinister-anterior side of the esophagus.According to one embodiment, the surgical method step of placing at least two posterior sutures or staplers, connecting the fundus to the esophagus, on the sinister-posterior side of the esophagus, comprises placing the at least two posterior sutures or staplers at least 0,5 cm posterior to a coronal plane intersecting a most cranial point of the fundus.According to one embodiment the surgical method step of placing at least two anterior sutures or staplers, connecting the fundus to the esophagus, on the sinister-anterior side of the esophagus, comprises placing the at least two anterior sutures or staplers at least 0,5 cm anterior from the coronal plane intersecting the most cranial point of the fundus.According to one embodiment, the surgical method step of placing at least two posterior sutures or staplers, connecting the fundus to the esophagus, on the sinister-posterior side of the esophagus comprises placing the most caudal suture or stapler at least 0,5 cm from the angle of His. According to one embodiment the surgical method step of placing at least two anterior sutures or staplers, connecting the fundus to the esophagus, on the sinister-anterior side of the esophagus comprises placing the most caudal suture or stapler at least 0,5 cm from the angle of His.According to one embodiment the surgical method step of placing at least two posterior sutures or staplers, connecting the fundus to the esophagus, on the sinister-posterior side of the esophagus comprises placing the most caudal suture or stapler at least 1,5 cm from the angle of His.According to one embodiment the surgical method step of placing at least two anterior sutures or staplers, connecting the fundus to the esophagus, on the sinister-anterior side of the esophagus comprises placing the most caudal suture or stapler at least 1,5 cm from the angle of His.According to one embodiment the surgical method step of placing the most caudal suture or stapler of the at least two posterior sutures or staplers, connecting the fundus to the esophagus, on the sinister-posterior side of the esophagus at least 0,5 cm from the angle of His and placing the most caudal suture or stapler of the at least two anterior sutures or staplers, connecting the fundus to the esophagus, on the sinister-anterior side of the esophagus at least 1,5 cm from the angle of His.According to one embodiment the surgical method step of placing the most caudal suture or stapler of the at least two posterior sutures or staplers, connecting the fundus to the esophagus, on the sinister-posterior side of the esophagus at least 1,5 cm from the angle of His and placing the most caudal suture or stapler of the at least two anterior sutures or staplers, connecting the fundus to the esophagus, on the sinister-anterior side of the esophagus at least 0,5 cm from the angle of His.According to one embodiment the surgical method step of connecting the fundus to the esophagus further comprises placing at least one central suture or stapler on a cranial-caudal axis extending between the at least two posterior sutures or staplers and the at least two anterior sutures or staplers. The step of placing at least one central suture or stapler on a cranial-caudal axis may comprise placing at least one central suture or stapler being disconnected from the at least two anterior sutures or staplers and from the at least two posterior sutures or staplers, for maintaining the possibility of radial expansion the esophagus for limiting the disk of dysphagia.According to one embodiment the surgical method step of placing at least two posterior sutures or staplers, connecting the fundus to the esophagus, on the sinister-posterior side of the esophagus, and placing at least two anterior sutures or staplers, connecting the fundus to the esophagus, on ...

Claims

1. An implantable medical device for treating reflux disease, the implantable medical device comprising a movement restriction device configured to be fixated to the stomach wall for hindering movement of the lower esophageal sphincter relative to the thoracic diaphragm, the movement restriction device comprises:%2. a central part, and%2. at least two outer parts, wherein the at least two outer parts are configured to be connected to each other along a vertical plane and wherein the at least two outer parts are configured to be connected to the central part for forming at least a portion of a functional movement restriction device, the central part and the at least two outer parts are capable of disconnecting from each other, such that the central part and the at least two outer parts individually can pass through the gastro-intestinal tract, wherein the central part comprises at least one horizontally extending rim extending in a direction perpendicular to the vertical plane and wherein the central part has at least one contacting surface configured to contact at least one surface of the at least two outer parts, and wherein a portion of the horizontally extending rim is wedge-shaped with an angle in the range 20° - 60°. 2. The implantable medical device according to aspect 1, wherein the portion of the horizontally extending rim is wedge-shaped with an angle exceeding 25°. 3. The implantable medical device according to aspect 1, wherein a portion of the horizontally extending rim is wedge-shaped with an angle exceeding 30° or exceeding 35°. 4. The implantable medical device according to any one of aspects 1 – 4, wherein the wedge-shaped portion of the horizontally extending rim is tapered in a direction away from the center of gravity of the central part. 5. The implantable medical device according to any one of aspects 1 – 5, further comprising at least two vertically extending rims extending substantially perpendicularly from the horizontally extending rim.  6. The implantable medical device according to aspects 6, wherein the vertically extending rims comprises wedge-shaped portions.  7. The implantable medical device according to aspects 7, wherein the wedge-shaped portion of the vertically extending rims are tapered in a direction away from the center of gravity of the central part. 8. The implantable medical device according to any one of aspects 7 and 8, wherein the wedge-shaped portions of the vertically extending rims are wedge-shaped with an angle in the range 20° - 60°. 9. The apparatus according to any one of the preceding aspects, wherein the implantable movement restriction device (110) comprises a first portion having a first volume enclosed by material of the implantable movement restriction device (110), and a second portion, different from the first portion, having a second volume enclosed by material of the implantable movement restriction device (110), wherein:the first volume and the second volumes are equally large, the first volume has a higher density than the second volume, and the second volume has a density below 1000 kg / m3. 9. The apparatus according to aspect 9, wherein the first volume comprises a first solid material. 10. The apparatus according to aspect 10, wherein the first solid material comprises a polymer material.  11. The apparatus according to aspect 11, wherein the first solid material comprises at least one of silicone-based material and a polyurethane-based material.  12. The apparatus according to any one of aspects 9 – 12, wherein the second volume comprises a second solid material. 13. The apparatus according to aspect 13, wherein the second solid material comprises a polymer material.  14. The apparatus according to aspect 14, wherein the second solid material comprises a at least one of a polypropylene-based and a polyethylene-based material.  15. The apparatus according to any one of aspects 13 – 15, wherein the first volume comprises a solid material having a density above 1000 kg / m3 and the second volume comprises a solid material having a density below 1000 kg / m3. 16. The apparatus according to any one of aspects 9 – 16, wherein the second volume comprises a gas. 17. The apparatus according to any one of aspects 9 – 17, wherein the second volume comprises a plurality of volumes of gas enclosed by an enclosing material. 18. The apparatus according to aspect 18, wherein the second volume comprises a solid polymer material enclosing the enclosing material, and wherein the enclosing material is harder than the solid polymer material. 19. The apparatus according to any one of aspects 18 and 19, wherein the plurality of volumes of gas enclosed by an enclosing material makes up at least 10 volume percent of the second volume, more preferably at least 20 volume percent of the second volume, and even more preferably at least 30 volume percent of the second volume. 20. The apparatus according to any one of aspects 18 – 20, wherein the enclosing material comprises glass. 21. The apparatus according to any one of the preceding aspects, wherein the implantable movement restriction device comprises an outer surface configured to rest against the stomach wall portion, and wherein an average surface roughness measured on the outer surface is no more than 0.5 µm. 22. The apparatus (100) according to aspect 22, wherein the average surface roughness is Ra as defined according to ISO 21920-2:2021. 23. The apparatus (100) according to aspect 22, wherein the average surface roughness is Sa as defined according to ISO 25178-2:2021. 24. The apparatus (100) according to any one of aspects 22 – 24, wherein the average surface roughness is in the range of 0.1–0.5 µm.  25. The apparatus (100) according to any one of aspects 22 – 25, wherein the average surface roughness is in the range of 0.1–0.3 µm.  26. The apparatus according to any one of the preceding aspects, wherein an indentation hardness on the Shore A scale measured on the outer surface of the movement restriction device is at least 50. 27. The apparatus according to aspect 27, wherein the indentation hardness is indentation hardness is measured by the durometer method defined in part 4 of ISO 48-4:2018. 28. The apparatus according to aspects 27 – 28, wherein an indentation hardness on the Shore A scale measured on the outer surface is no more than 70. 29. The apparatus according to any one of aspects 27 – 29, wherein an indentation hardness on the Shore A scale measured on the outer surface is in the range of 55 to 65. 31.The apparatus according to any one of the preceding aspects, wherein the implantable movement restriction device comprises a contrast agent.   32. The apparatus according to aspect 31, wherein the contrast agent is BaSO4.  33. The apparatus according to aspect 31 or 32, wherein the implantable movement restriction device comprises the contrast agent in an amount of 1–15 % by weight of the implantable movement restriction device. 34. The apparatus according to aspect 33, wherein the implantable movement restriction device comprises the contrast agent in an amount of 1–6% by weight of the implantable movement restriction device. 35. The apparatus according to aspect 34, the implantable movement restriction device comprises the contrast agent in an amount of 8–15 % by weight of the implantable movement restriction device.  

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