Implantable medical device comprising a force detection or force variation detection sensor

Abstract

An implantable medical device (10), such as a lumbar interbody cage, equipped with a sensor configured to detect a force or a variation of a force exerted on the device (10).

Description

Implantable medical device comprising a force or force variation detection sensor

[0001] The present invention relates to the field of implantable medical devices.

[0002] The invention is of particular interest, but not limited to, the context of arthrodesis, also known as bone fusion. State of the art

[0003] An arthrodesis allows vertebrae to be locked together, typically to eliminate pain and reduce neurological risks resulting from pathological spinal instability.

[0004] To achieve this, it is known to place an interbody cage between two vertebrae, in place of a previously removed intervertebral disc. Such a cage allows, on the one hand, for the vertebrae between which it is placed to be kept apart and, on the other hand, for bone healing to be ensured by means of a bone graft placed in or around the cage.

[0005] There is a need to improve the detection of a lack of bone fusion after implantation of such an interbody cage.

[0006] The invention relates to an implantable medical device comprising a body and an electronic system, the electronic system comprising at least one sensor and being configured to transmit data measured by the sensor to a remote device, the sensor being configured to detect at least one force or variation of a force exerted on the device.

[0007] The invention thus makes it possible to detect forces or variations in forces exerted on the device when it is implanted.

[0008] When the device forms an interbody cage, it is possible to monitor the fusion process of two vertebrae and in particular to detect an absence of bone fusion which typically results in the presence of relative movements of these vertebrae, one in relation to the other and / or in relation to the implanted device.

[0009] In a preferred, non-limiting embodiment, the sensor includes at least one strain gauge.

[0010] Alternatively or in addition, the device may include one or more other types of sensors.

[0011] The electronic system may include an electronic chip.

[0012] This electronic chip may be a radio-frequency identification chip.

[0013] In an embodiment in which the electronic system includes an electronic chip, the latter can be configured to undergo deformation under the action of said force, the sensor being configured to detect a deformation of the electronic chip.

[0014] In other words, the electronic system of the device of the invention may include a component, in particular a chip, forming a proof body.

[0015] In such an embodiment, the sensor can be a strain gauge fixed to the chip and / or to another element attached to the chip.

[0016] In one embodiment, the device includes a force transmission element configured to be displaced and / or deformed relative to the body, or relative to a part of the body, under the action of said force so as to stress the sensor.

[0017] The device can of course include both a force transmission element and a test body, for example a test body as defined above which can be formed by a component of the electronic system and / or by another element of the device.

[0018] Alternatively, the device may include a force transmission element and be devoid of a test body.

[0019] In general, when the device includes a force transmission element, this can be formed by the body of the device and / or by the electronic system and / or by any other element of the device.

[0020] The device may include one or more additional elements, for example a lid.

[0021] In one embodiment, such a cover forms said force transmission element.

[0022] Without limitation, the cover may include a rigid part forming said force transmission member and one or more flexible parts which are connected to the rigid part and which cooperate with the body in such a way as to allow a displacement of the rigid part of the cover relative to the body, or relative to a part of the body.

[0023] In one embodiment, the body comprises a fixed part and a movable part relative to the fixed part, said movable part of the body forming said force transmission organ.

[0024] In summary and without limitation, the device of the invention can thus be configured so that said force is exerted: on the body of the device, or on a transmission element of the device, or on a test body, or directly on the sensor.

[0025] When force is exerted on the body of the device, it can be configured to transmit this force to the sensor directly through the body itself or via a test body and / or a force transmission element.

[0026] When force is exerted on a force transmission element, the device can be configured to transmit this force to the sensor directly through the force transmission element or via a test body.

[0027] When the device includes a force transmission element, this can be formed by a part of the device body and / or by an element cooperating with the device body, such as a cover or a tab.

[0028] When the device includes a test body, this can be formed by a component of the electronic system, for example an electronic chip, and / or by a part of the body, and / or by an element of the device which can for example form a beam or an elongated element or more generally a deformable element.

[0029] Without limitation, the device sensor may include: a strain gauge, particularly when the device includes an element forming a test body, another type of sensor, including a force sensor, an atmospheric pressure measuring sensor, which can typically be configured to measure pressure within a space formed by the device body and / or another device element.

[0030] In one embodiment, the body and / or one or more other elements of the device, for example the cover when the device includes one, comprises a thermoplastic material, for example a polyetheretherketone.

[0031] Among other advantages, such a material is radiotransparent and helps to reduce electromagnetic interference.

[0032] In one embodiment, the device forms an interbody cage, for example lumbar.

[0033] In another embodiment, the device forms an orthopedic prosthesis, for example a knee prosthesis.

[0034] The invention is not limited to such a device; the invention can be implemented to form other types of implantable medical devices.

[0035] The invention also relates to an assembly comprising an implantable medical device as defined above and a device configured to receive data measured by the sensor of the implantable medical device.

[0036] In one embodiment, said device is configured to transmit to the electronic system of the implantable medical device electromagnetic signals forming a source of energy suitable for powering the electronic system.

[0037] The invention also relates to a method for assembling an implantable medical device as defined above.

[0038] The process more specifically includes a step of assembling the body and the electronic system together.

[0039] The assembly stage can typically include an operation of arranging all or part of the electronic system within one or more cavities formed by the body of the device.

[0040] When the device includes a cover, the assembly step may include an operation of attaching the electronic system to the cover and / or an operation of closing one or more of said cavities receiving the electronic system.

[0041] The invention also relates to a method of implanting, in the body of an individual, an implantable medical device as defined above.

[0042] The implantation procedure can be performed as part of an arthrodesis, but is not limited to other procedures.

[0043] Other advantages and features of the invention will become apparent from the detailed, non-limiting description that follows. Brief description of the figures

[0044] The detailed description that follows refers to the accompanying drawings in which: a is a schematic profile view of a portion of a human vertebral column showing two vertebrae of this vertebral column, as well as an interbody cage disposed between these two vertebrae; a is a schematic perspective view of an implantable medical device according to the invention forming an interbody cage, the device comprising a body and a cover and being intended to receive an electronic system provided with a sensor for detecting a force or a change in a force exerted on the device; a is a schematic perspective view of the body of the device; a is a schematic perspective view of the cover of the device, showing an external protrusion of the cover; a is a schematic perspective view of the cover of the device, showing an internal protrusion of the cover;la is a schematic perspective view of an antenna of an electronic system intended to equip the device of the; la is a schematic perspective view of an electronic system intended to equip the device of the, this electronic system comprising the antenna of the, a circuit, a radio-identification chip, as well as a strain gauge; la is a schematic view of an assembly comprising a first device forming an implantable medical device according to the invention and a second device configured to communicate remotely with the first device; la is a schematic perspective view of an implantable medical device according to the invention, the device comprising a deformable body and being intended to receive an electronic system provided with a sensor for detecting a force or a variation of a force which is exerted on the device;This is a schematic cross-sectional view of part of the device, showing a test body housed in a cavity of the device body, the test body carrying a strain gauge of an electronic system equipping the device. Detailed description of implementation methods

[0045] It is represented on a part of a human vertebral column 1, showing two vertebrae 2 and 3 of the lumbar spine of this vertebral column 1 which correspond in this non-limiting example to vertebrae L4 and L5, respectively.

[0046] Lamontre also a medical device 10 according to the invention, which is positioned between vertebrae 2 and 3 in place of an intervertebral disc (not shown) initially interposed between these vertebrae and which has been previously removed as part of an arthrodesis.

[0047] The device 10 of the invention thus forms, within the framework of this non-limiting example, a lumbar interbody cage, for example a cage such as illustrated in the.

[0048] As is known in itself, an interbody cage 10 is intended on the one hand to keep apart the vertebrae between which it is placed and, on the other hand, to ensure bone consolidation with the help of a bone graft housed in an opening 11 of the cage 10 (see).

[0049] Device 10 of the invention allows in this example to monitor the fusion process of two vertebrae and, more specifically, to detect an absence of bone fusion which typically results in the presence of relative movements of these vertebrae, one with respect to each other and / or with respect to device 10.

[0050] The invention is not, however, limited to lumbar interbody fusions. In particular, the device of the invention can form a cervical or thoracic interbody cage.

[0051] More generally, the principles described in this document can be used to create different types of implantable medical devices used to detect or measure a force or a change in force exerted on such an implanted device.

[0052] Thus, in a non-limiting variant, the device of the invention can form an orthopedic prosthesis such as a knee prosthesis (not shown).

[0053] The following description relates to the particular case of a lumbar interbody cage and applies by analogy to all devices conforming to the invention, including those mentioned above.

[0054] Figures 2 to 7 illustrate an embodiment in which the device 10 comprises a body 12 (figures 2 and 3), a cover 13 (figures 2, 4 and 5) and an electronic system 14 (figures 6 and 7).

[0055] Figures 2 to 7 include a reference frame defining directions D1, D2 and D3 which indicate a relative arrangement of the different components of device 10 when it is assembled.

[0056] With reference to the, the body 12 is generally presented in the form of a ring defining an opening 11 which passes through the body 12 from one side to the other along the direction D1.

[0057] The body 12 has an internal surface 12A which delimits the opening 11, an external surface 12B which delimits an outer perimeter of the body 12 along the directions D2 and D3, as well as a lower surface 12C and an upper surface 12D which constitute respective ends of the body 12 along the direction D1.

[0058] In this example, surfaces 12A and 12B each have a curvilinear geometry, i.e., including curved parts, while surfaces 12C and 12D are substantially flat.

[0059] In terms of bulk, the body 12 has a thickness X1, corresponding to the distance between surfaces 12C and 12D, a transverse dimension X2 which corresponds to its dimension along the direction D2, as well as a transverse dimension X3 which corresponds to its dimension along the direction D3.

[0060] In this example, each of the dimensions X1 and X2 varies along the direction D3, while X3 varies along the direction D2.

[0061] The body 12 thus forms: a front part (towards the left of the) and a rear part (towards the right of the) which are spaced apart from each other along the direction D3, and two lateral parts (respectively towards the top and towards the bottom of the) which are spaced apart from each other along the direction D2.

[0062] In this embodiment, body 12 is made of polyetheretherketone.

[0063] With further reference to the, the body 12 comprises in this embodiment three cavities 21, 22 and 23 stacked along the direction D1.

[0064] Cavity 21 opens onto the upper surface 12D.

[0065] The cavity 21 is more specifically delimited by a surface 12E of the body 12 which extends substantially parallel to the surface 12D, the distance along D1 between the surfaces 12D and 12E defining a depth of the cavity 21.

[0066] In this example, the cavity 21 comprises a so-called central part which extends over the said front part of the body 12, as well as two so-called lateral parts which each extend over a respective portion of each of the said lateral parts of the body 12 (see).

[0067] Regarding cavity 22, it opens into cavity 21, in particular onto surface 12E of body 12.

[0068] The cavity 22 is delimited by two surface elements 12F of the body 12 (only one surface element 12F being visible on the), these two surface elements 12F being spaced from each other along the direction D2.

[0069] The surface elements 12F extend substantially parallel to the surface 12E, the distance along D1 between the surfaces 12E and 12F defining a depth of the cavity 22.

[0070] Regarding cavity 23, it opens into cavity 22, in particular onto the surface elements 12F of body 12.

[0071] The cavity 23 is delimited by a surface 12G of the body 12, the surface 12G extending substantially parallel to the surface 12E and to the surface elements 12F, the distance along D1 between the surfaces 12F and 12G defining a depth of the cavity 23.

[0072] In this example, cavities 21, 22 and 23 are sized to receive respective parts of the electronic system 14 and the cover 13.

[0073] With reference to figures 4 and 5, the cover 13 has a geometry that is generally similar to that of the cavity 21 of the body 12.

[0074] The cover 13 has a lower surface 13A (see) and an upper surface 13B (see) which are substantially flat and parallel. The surfaces 13A and 13B are spaced apart along direction D1 by a distance defining the thickness of the cover 13.

[0075] As an indication, the cover 13 can have a thickness of around 500 µm.

[0076] The lid 13 forms a central part 31 and two lateral branches 32 attached to the central part 31.

[0077] The lateral branches 32 of the cover 13 are spaced apart along the direction D2 and each extend along the direction D3, exhibiting a curved geometry.

[0078] In this example, the cover 13 includes an element 34 forming an external protrusion which extends to the surface 13B of the central part 31 of the cover 13 (see).

[0079] With reference to the, the cover 13 also includes an element 35 forming an internal protrusion which extends to the right of the surface 13A of the central part 31 of the cover 13.

[0080] In this non-limiting example, the protuberances 34 and 35 are substantially aligned with each other along the directions D2 and D3 and each extend at an equidistance from the lateral branches 32 of the cover 13 along the direction D2.

[0081] In this embodiment, the lid 13 is made of polyetheretherketone.

[0082] With reference to the, the electronic system 14 includes in this non-limiting example an antenna 41, an electronic circuit 42, an electronic chip 43 and a sensor 44.

[0083] Antenna 41 has a geometry that is broadly similar to that of cover 13.

[0084] The antenna 41 has a lower surface 41A (see) and an upper surface 41B (see) which are substantially flat and parallel. The surfaces 41A and 41B are spaced apart along the direction D1 by a distance defining the thickness of the antenna 41.

[0085] As an indication, antenna 41 can have a thickness of around 150 µm.

[0086] With reference to the, the antenna 41 forms a central part 51 and two lateral branches 52 attached to the central part 51.

[0087] The lateral branches 52 of the antenna 41 are spaced apart along the direction D2 and each extend along the direction D3, exhibiting a curved geometry.

[0088] The central part 51 of the antenna 41 includes an opening 53 which passes through it in the direction D1 so as to open onto each of the surfaces 41A and 41B.

[0089] With reference to the, the electronic circuit 42 includes in this example an epoxy polymer substrate having, as an indication, a thickness that can be on the order of 0.8 mm.

[0090] In this example, chip 43 is a radio-frequency identification (RFID) chip and sensor 44 is a strain gauge, also called an extensometer gauge or strain gauge.

[0091] Lamontre the assembled electronic system 14, the antenna 41, the circuit 42, the chip 43 and the sensor 44 being fixed to each other by being stacked along the direction D1.

[0092] More specifically, one side of circuit 42 is fixed to surface 41A of the central part 51 of the antenna 41, and chip 43 is fixed to a second side of circuit 42, opposite the first side. Sensor 44 is fixed to the side of chip 43 opposite the side fixed to circuit 42.

[0093] The assembly of the sub-assembly with the cover 13 is carried out by fixing the surface 41B of the antenna 41 onto the surface 13A of the cover 13, so that the central part 51 and the lateral branches 52 of the antenna 41 are respectively opposite the central part 31 and the lateral branches 32 of the cover 13, and so that the internal protrusion 35 of the cover 13 extends through the opening 53 of the antenna 41.

[0094] The cover 13 and the electronic system 14 thus assembled are then assembled with the body 12 of the device 10, according to the configuration illustrated at which is a reference configuration.

[0095] In the reference configuration, the cover 13 and the antenna 41 are housed in the cavity 21 of the body 12, bearing on the surface 12E of the body 12 such that the surface 12F of the body 12 and the surface 13B of the cover 13 are substantially coplanar, the circuit 42 is received in the cavity 22 of the body 12, bearing on the surface elements 12F of the body 12, while the chip 43 and the sensor 44 extend in the cavity 23 of the body 12 of the device 10 opposite the surface 12G of the body 12.

[0096] In this example, the device 10 is dimensioned so that, in the reference configuration, the sensor 44 extends to a non-zero distance from the surface 12G of the body 12, in order to allow a relative displacement of the electronic system 14 in the direction of the surface 12G of the body 12 (see further below).

[0097] In the embodiment of figures 2 to 7, the chip 43 forms a test body configured to stress the sensor 44 when it is deformed under the action of a force exerted on the device 10 and in particular on the external protrusion 34 of the cover 13, in particular when this force has at least one component along the direction D1.

[0098] The protrusions 34 and 35 and the central part 31 of the cover 13, together with the circuit 42 of the electronic system 14, form a transmission element of such an effort which allows the chip 43 to be deformed under the action of such a force.

[0099] From the rest configuration illustrated in the figure, the device 10 is thus configured to allow a deformation of the cover 13 under the action of a force exerted on the external protrusion 34 of the device 10, in a so-called positive direction going in this example from the top to the bottom of the figure, the deformation of the cover 13 being substantially proportional to the amplitude of this force, at least when this force is within a predetermined range.

[0100] The deformation of the cover 13 in this example causes a relative displacement of the central part 31 and the protrusions 34 and 35 of the cover 13 on the one hand with respect to the lateral branches 32 of the cover 13 and, on the other hand, with respect to the body 12 of the device 10, in this example in the said positive direction, that is to say in the direction of the surface 12G of the body 12.

[0101] Such a deformation of the cover 13 causes, via the internal protrusion 35, a corresponding deformation of the circuit 42 which comes to rest on the surface elements 12F of the body 12 and, consequently, a corresponding deformation of the chip 43 which thus stresses the sensor 44.

[0102] During such a deformation, the chip 43 and the sensor 44 are displaced in the cavity 23 towards the surface 12G of the body 12, the cavity 23 being of course dimensioned to allow such a displacement taking into account the typical forces likely to be exerted on the device 10.

[0103] The sensor 44, which is here a strain gauge, is thus configured to detect a force or a change in a force exerted on the device 10.

[0104] Lamontre a set 100 comprising an implantable medical device 10 according to the invention and another device 60, also called "apparatus", which is distant from the device 10.

[0105] Devices 10 and 60 are configured to exchange information without a wired connection.

[0106] The device 10 can typically be that described above with reference to figures 2 to 7 or according to any other embodiment of the invention.

[0107] In this example, device 60 includes an antenna 61 configured to communicate with the electronic system 14 of device 10 by electromagnetic means.

[0108] Without limitation, devices 10 and 60 are configured to communicate signals with each other having a frequency in the range of 860 MHz to 960 MHz, i.e., the ultra-high frequency band. Devices 10 and 60 are more preferably configured to communicate signals whose frequency is selectively chosen within a desired band, which may be the band from 865 MHz to 868 MHz, or from 915 MHz to 921 MHz, or from 902 MHz to 928 MHz.

[0109] Device 60 can thus receive data provided by the electronic system 14 of device 10, including data measured by sensor 44.

[0110] The electronic system 14 of the device 10 can be powered by the signals emitted by the antenna 61 of the device 60 and / or by an energy source on board the device 10.

[0111] Such a mode of communication and supply is of course not limiting and can be substituted by other conventional means or protocols.

[0112] A set 100 such as that of the can be used in the context of a lumbar interbody fusion as described above with reference to the. The medical device 10 can be implanted between two vertebrae of an individual, typically in an arrangement in which the D1, D2 and D3 directions extend substantially along the longitudinal, transverse and anteroposterior anatomical axes, respectively.

[0113] During relative movements of the vertebrae between which the device 10 is positioned, one of the vertebrae, in contact with the external protrusion 34 of the device 10, exerts a force on the device 10 which can thus be detected by the sensor 44. The measurement data from the sensor 44 can be communicated to the device 60 in the manner described above, by positioning this device 60 against the body of the individual in whom the device 10 is implanted, opposite this device 10. Under these conditions, the devices 10 and 60 can typically be spaced from each other by a distance of between 10 cm and 30 cm, for example a distance of 15 cm.

[0114] In the embodiment shown in Figures 2 to 7, the sensor 44 of the device 10 is housed within the device 10 and therefore does not come into direct contact with a vertebra or the individual's tissues. This configuration of the sensor 44 avoids impacting the surgical procedure and preserves the integrity of the sensor 44 despite the significant forces that may be applied to the device 10.

[0115] Of course, the invention is not limited to the preceding description and many variants can be envisaged without departing from the scope of the invention which is defined by the claims, the preceding description applying by analogy to all the variants described below and to their combinations.

[0116] In particular, as an alternative to the embodiment shown in Figures 2 to 7, the device can be configured so that the force to be detected is applied to a part of the device which has a geometry different from that of the external protrusion 34 shown in Figures 2 and 4, including a planar or curvilinear geometry which can generally be formed by the body of the device and / or by its cover and / or by any other component of the device.

[0117] In an alternative embodiment not shown, in which the medical device includes a lid, the medical device may include a force transmission element which, unlike that of the embodiment in Figures 2 to 7, is not formed by the lid. Such a force transmission element may, in particular, be configured to be moved by a force acting upon it without causing the lid to move. By way of example, this transmission element may, for instance, pass through an opening in the lid and be guided by the lid and / or the device body during its movement.

[0118] In the embodiments just described, the device includes a lid. However, the device of the invention may be without a lid, for example in the following non-limiting embodiments.

[0119] Typically, but without the absence of a lid being a limiting condition, a device without a lid can be configured to stimulate the sensor by deforming the body of the device.

[0120] For this purpose, the body of the device may comprise a fixed part and a part that moves relative to the fixed part. Such a moving part of the device body can thus form a force transmission element to the sensor.

[0121] In an embodiment not shown, such fixed and moving parts are each formed by one or more respective magnets which tend to return the body to a rest configuration, in which the fixed part and the moving part are separated from each other by an initial distance, the device being configured so that the force to be detected which is applied to it reduces this distance, typically in proportion to the magnitude of this force.

[0122] In another embodiment not shown, the moving part of the body can be formed by one or more tabs that are elastically deformable relative to the fixed part of the body.

[0123] In the embodiment shown in Figures 9 and 10, the body 12 of the device 10 includes an opening 110 in the form of a groove extending along direction D2 so as to delimit a lower part 111 and an upper part 112 of the body 12, the opening 110 being configured to allow relative displacement of parts 111 and 112 with respect to each other when the device 10 is subjected to a force acting along direction D1. In this example, an elongated member 120 along direction D2 is received in a cavity of the body 12, the ends of the member 120 bearing against respective surfaces of the body 12 (not visible in Figures 9 and 10). The member 120 forms a test body carrying a strain gauge, the device 10 being configured to deform the member 120 under the action of a relative displacement of the parts 111 and 112 with respect to each other.Device 10 includes, of course, an electronic system, not shown in Figures 9 and 10, which allows communication of measurement data provided by the gauge.

[0124] Whether or not the body of the device of the invention includes a cover, the latter may have a geometry making it expandable, typically in order to maintain contact of the device – for example of the body and / or the cover and / or the sensor – with the vertebrae, or more generally with the parts of the body of the individual in which the device is implanted.

[0125] In one embodiment, not shown, the device includes a sensor arranged to come into direct contact with a vertebra or, more generally, with a part of the body of the individual in whom the device is implanted. Such a sensor may, for example, be substantially flush with an external surface of the device body.

[0126] In an unrepresented variant in which the device includes a force-transmitting element—formed, for example, by the cover and / or a movable part of the device body—the force-transmitting element can serve as an anchoring element to a bone or tissue, or more generally to a part of the individual's body in which the device is implanted. For example, the body can include a tab as defined above, or a screw, configured to be secured to a vertebra.

[0127] The device of the invention may also include one or more additional elements, for example one or more springs configured to return the body to the rest configuration, and / or a sealing element configured to form said force transmission element, and / or a temperature sensor configured to measure the surrounding temperature.

[0128] The body and / or cover of the device of the invention may generally comprise a thermoplastic material and / or titanium and / or other materials.

[0129] In particular, when the sensor includes a strain gauge mounted on a test body, the device can be configured to stress the strain gauge by stretching the test body or by subjecting it to other types of stress, for example torsion.

[0130] In general, when the device includes a test body, this may be formed in whole or in part by one or more elements other than an RFID chip or more generally than a component of the electronic system.

[0131] Of course, the device of the invention may include several sensors configured to detect one or more forces – or variations of forces – exerted on the device.

[0132] Furthermore, force or force variation detection can be achieved using various types of sensors, which can be selected from a list including, but not limited to, strain gauges, force or strain sensors configured to detect, for example, compressive and / or tensile and / or torsional and / or torque and / or linear and / or angular displacement forces, resistive sensors, capacitive sensors, piezoelectric sensors, inductive sensors, Hall effect sensors, and atmospheric pressure sensors. When using an atmospheric pressure sensor, it can be housed within a chamber of the device body and / or encapsulated in silicone or another material.

Claims

Implantable medical device (10) comprising a body (12) and an electronic system (14), the electronic system (14) comprising at least one sensor (44) and being configured to transmit data measured by the sensor (44) to a remote device (60), the sensor (44) being configured to detect at least one force or change in a force exerted on the device (10). Device (10) according to claim 1, wherein the sensor (44) comprises at least one strain gauge. Device (10) according to claim 1 or 2, wherein the electronic system (14) comprises an electronic chip (43), such as a radio-frequency identification chip, configured to undergo deformation under the action of said force, the sensor (44) being configured to detect a deformation of the electronic chip (43). Device (10) according to any one of claims 1 to 3, comprising a force transmission member (34, 35, 42; 112) configured to be displaced and / or deformed relative to the body (12), or relative to a part of the body (111), under the action of said force so as to stress the sensor (44). Device (10) according to claim 4, comprising a cover (13) forming said force transmission member, the cover (13) comprising for example a rigid part (34, 35) forming said force transmission member and one or more flexible parts (31, 32) which are connected to the rigid part (34, 35) and which cooperate with the body (12) so as to allow a displacement of the rigid part (34, 35) of the cover (13) relative to the body (12), or relative to a part of the body. Device (10) according to claim 4 or 5, in which the body (12) comprises a fixed part (111) and a movable part (112) relative to the fixed part (111), said movable part (112) of the body (12) forming said force transmission member. Device (10) according to any one of claims 1 to 6, forming an interbody cage, for example a lumbar interbody cage. Device (10) according to any one of claims 1 to 6, forming an orthopedic prosthesis, for example a knee prosthesis. Assembly (100) comprising an implantable medical device (10) according to any one of claims 1 to 8 and an apparatus (60) configured to receive data measured by the sensor (44) of the implantable medical device (10), said apparatus (60) being preferably configured to transmit to the electronic system (14) of the implantable medical device (10) electromagnetic signals forming an energy source suitable for powering the electronic system (14). Method of assembling an implantable medical device (10) according to any one of claims 1 to 8, comprising a step of assembling the body (12) and the electronic system (14) together.

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