Implant for fixing the cranial flap to the cranial opening

Abstract

The present invention relates to an implant for fixing a skull flap in a skull opening, the implant comprising: a longitudinal axis extending along the axial direction of the skull opening; a transverse axis extending along the radial direction of the skull opening; a first portion designed to transmit a force to the bone flap; a second portion designed to transmit a force to a skull surrounding the skull opening, the first portion and / or the second portion being designed to be placed in an annular gap formed between an outer periphery of the bone flap and an inner periphery of the skull; and a mechanism operatively connected to the first portion and the second portion, the mechanism being capable of at least expanding a lateral space between the first portion and the second portion projected on the transverse axis, such that the first portion can be pressed radially inward against the bone flap and the second portion can be pressed radially outward against the skull.

Description

[Technical field]

[0001] The present invention relates to an implant for securing a skull flap in a cranial opening.

[0002] Neurosurgical procedures on the brain are generally performed through an opening in the skull. The creation of such a skull opening is also called a craniotomy. In a craniotomy, a portion of the skull bone is separated from the skull, for example by a burr hole. The separated portion is also called a bone flap or bone fragment. After the operation, the bone flap is repositioned and fixed into the previously created skull opening.

[0003] For fixing the bone flap, implants in the form of so-called clamping systems are known. For example, a clamping system named CranioFix® 2 from Aesculap AG, Tuttlingen, Germany is known. This known clamping system has an upper disk element, a lower disk element and a rod element that movably connects the two disk elements to each other. The rod element extends along a longitudinal axis between an upper end and a lower end, the upper disk element being attached to the upper end and the lower disk element being attached to the lower end. To fix the bone flap, the lower disk element is first placed in the epidural space and the rod element is placed approximately parallel to the axial direction of the skull opening. The bone flap is repositioned in the skull opening and its inner side is placed on the lower disk element. The rod element now extends from the inner side of the skull to the outer side of the skull through the annular gap formed between the bone flap and the surrounding skull. For final fixation, the upper disk element is moved along the rod element, i.e. in the axial direction of the skull opening, approaching the lower disk element. For this purpose, a screwing or latching mechanism is provided. In the final fixed state, the two disk elements are fixedly pressed against the outside of the bone flap and against the inside of the bone flap and the surrounding skull in the axial direction of the skull opening. Summary of the Invention

[0004] With regard to known clamping systems, various aspects are considered to be disadvantageous: The placement of the lower disc element in the epidural space may, under certain conditions, irritate the dura and, in the worst case, cause an epidural hematoma. This is because the axial clamping of the disc element poses the risk of unintentional pressure on the dura, which may ultimately cause an epidural hematoma. To avoid unintentional compression forces on the dura, a special tool is provided in CranioFix2 to hold the rod element. If additional tools are required, the overall handling may become more difficult. Furthermore, after fixation, the upper disc element remains permanently outside the skull. This is particularly disadvantageous in cosmetically important areas, for example in frontal craniotomies. Since the upper and lower disc elements must be placed as flat as possible on the skull and bone flap for a satisfactory fixation, fixation is often impossible or unsatisfactory in cases where the skull is significantly curved or has a gradient in thickness. Also, a large curvature may cause the upper disc elements to protrude outside the skull, which may result in a poor cosmetic result or scalp irritation.

[0005] The object of the present invention is to provide an implant of the type mentioned at the outset, which offers advantages over the prior art, in particular to at least partially overcome or mitigate the disadvantages contained in the prior art.

[0006] This object is achieved by providing an implant having the features of claim 1. The dependent claims relate to advantageous configurations, the language of which is incorporated into the present specification by express reference.

[0007] The implant according to the invention for fixing a cranial bone flap in a cranial opening comprises a longitudinal axis extending along the axial direction of the cranial opening, a transverse axis extending along the radial direction of the cranial opening, a first part designed to transmit a force to the bone flap, a second part designed to transmit a force to the skull surrounding the cranial opening, the first part and / or the second part being designed to be placed in an annular gap formed between the outer circumference of the bone flap and the inner circumference of the skull, and a mechanism operatively connected to the first part and the second part, which mechanism is capable of at least enlarging a transverse space between the first part and the second part projected on the transverse axis, so that the first part can be pressed radially inwards against the bone flap and the second part can be pressed radially outwards against the skull. The solution according to the invention allows a radial fixation with respect to the orientation of the cranial opening. The force applied for fixation by the implant therefore acts radially, on the bone flap for one part and on the surrounding skull for the other part. In other words, the force applied acts in the plane of the skull or bone flap and not, for example, in their thickness direction. This is in contrast to solutions known from the prior art that provide fixation in an axial direction. Fixation in a radial direction avoids the application of unintended compressive forces to the dura and the associated risks. It is assumed that the application of a radial force, i.e. a force acting in a plane, leads to an improved regeneration of the skull. In the case of the solution according to the invention, the application of the force required for fixation is performed by a modification, more specifically an enlargement, of the lateral space projected on the lateral axis between the first and second parts. Since the lateral axis runs along the radial direction of the skull opening and is preferably arranged parallel, the enlargement of the projected lateral space exerts the above-mentioned radial contact pressure on both the bone flap and the skull. As a result, the annular gap is enlarged in the region of the implant, which necessarily leads to a reduction of the annular gap on the side of the skull opening diametrically opposite the implant. Thus, on the opposite side of the implant, the bone flap and the surrounding skull are pressed together and ultimately fixed by the action of the implant, creating bone-to-bone contact that contributes to improved regeneration.Such bone-to-bone contact is not absolutely necessary, especially when multiple implants are used spaced apart around the circumference of the bone flap. The mechanism operatively connected to the first and second parts is designed to increase at least the projected lateral space between said parts. The increase in lateral space can also be called spreading apart or spreading apart action. Different configurations of the invention have different mechanisms for generating the spreading apart action. For example, the spreading apart action can be brought about by a translational and / or rotational movement, especially a relative movement, of the two parts. To transmit a force to the bone flap, the first part has different forms in different configurations of the invention. In one configuration, the first part acts, preferably directly, on the periphery of the bone flap. In a further configuration, the first part is inserted in a bore extending radially around the periphery of the bone flap. The same applies to the second part. The mechanism is preferably designed to be manually actuated by the surgeon. The actuation can be purely manual or with a tool suitable for this. The longitudinal and transverse axes of the implant are arranged perpendicular to each other. For fixing the cranial bone flap and / or in its fixed state, the longitudinal axis is arranged along, preferably parallel to, the axial direction of the cranial opening. The transverse axis in this case is oriented along, preferably parallel to, the radial direction of the cranial opening. In a preferred configuration, the mechanism is further designed to reduce the projected transverse space. The reduction of the projected transverse space allows for an easy separation of the previously performed fixation. This makes revision surgery easier.

[0008] In one configuration of the invention, the mechanism is designed to translate the first and / or second part along a transverse axis. Thus, at least one of the two parts is translated along the transverse axis to generate the spreading apart movement. In one configuration, the mechanism allows the displacement of the first part along the transverse axis and the second part is fixed with respect to the transverse axis. In a further configuration, the mechanism allows the displacement of the second part along the transverse axis and the first part is fixed with respect to the transverse axis. In a further configuration, the mechanism allows the displacement of both parts along the transverse axis, in which case the parts are displaced in opposite directions to each other.

[0009] In a further configuration of the invention, the mechanism is designed for a rotational displacement of the first part and / or the second part about a longitudinal axis. In order to generate a spreading movement, in this configuration at least one of the two parts is rotationally displaced about a longitudinal axis. In one configuration, the mechanism allows for a rotational displacement of the first part, the second part being fixed about the longitudinal and / or transverse axis. In a further configuration, the mechanism allows for a rotational displacement of the second part, the first part being fixed about the longitudinal and / or transverse axis. In a further configuration of the invention, the mechanism provides for a rotational displacement of both parts about the longitudinal axis, preferably in the same direction.

[0010] In a further configuration of the invention, the first part has a first contact surface designed to bear against the outer circumference of the bone flap in the radial direction. Alternatively or additionally, the second part has a second contact surface designed to bear against the inner circumference of the skull in the radial direction. In this configuration of the invention, the forces are therefore transmitted via a preferably direct contact pairing between the relevant part and the respective peripheral surface of the relevant bone structure, i.e. the bone flap or the surrounding skull. This makes it possible, in particular, to do without special preparation or processing of the respective bone structure, in particular the introduction of bores or the like. The bone flap usually has a generally circular shape. The shape of the skull opening is similar. As a result, the curvature of the outer circumference of the bone flap is usually convex. The curvature of the skull surrounding the skull opening is therefore concave. The first and / or second contact surfaces preferably have correspondingly complementary curvatures. This enables the first contact surface to support against the outer periphery of the bone flap over as much of its surface area as possible, and / or the second contact surface to support against the inner periphery of the skull over as much of its surface area as possible.

[0011] In a further configuration of the invention, the first part has a joint surface, which is designed to be inserted into a bore extending radially at the periphery of the bone flap. Said bore may be formed radially in the bone flap in a separate operating step and serves to receive the first part at least partially. The first part is cylindrical, its shape is complementary to the bore and preferably has a circular cross section. The joint surface preferably comprises at least one outer side and / or end surface of the first part. For the purpose of positioning and / or pre-fixation, the first part is inserted axially into the bore. The form-fit and / or pressure-fit established here prevents the first part from inadvertently slipping off the periphery of the bone flap. It is important to realize that the insertion of the first part, and more particularly its joint surface, into the bore does not yet establish fixation by itself. Fixation is achieved via the application of the spreading apart movement described above, i.e. the widening of the projected lateral space between the first and second parts, after the first part has been inserted into the bore.

[0012] In a further embodiment of the invention, a support is present, which is arranged above the first and second parts along the longitudinal axis and has an underside designed to support the outer surface of the skull and the outer surface of the bone flap. The support serves to facilitate the positioning of the implant during fixation and to prevent inadvertent axial displacement into the epidural space. The underside of the support faces the outer surface of the bony skull and / or is oriented along the longitudinal axis. In different configurations, the support has different shapes, in particular plate-shaped, disk-shaped and / or ring-shaped shapes are conceivable. In the supported state, the underside rests on the outer surface of the bone flap on one side of the annular gap and on the outer surface of the skull on the opposite side of the annular gap. The support extends along the transverse axis between the bone flap on one side and the skull on the other side.

[0013] In a further configuration of the invention, the support is connected to the remaining part of the implant by a removable joint connection means, in particular a bayonet closure. This configuration allows the support to be removed after the fixation is completed. For this purpose, the above-mentioned removable joint connection between the support and at least one further component and / or part of the implant is formed. The above-mentioned removable joint connection is preferably a bayonet closure. Removing the support after the fixation is completed allows the structural height of the implant to be reduced in relation to the longitudinal axis. In particular, the support does not remain permanently outside the skull, which would result in cosmetic, medical and / or other negative consequences.

[0014] In a further configuration of the invention, at least one mandrel part is present, which extends along a transverse axis and at one end projects beyond the first part and has a mandrel tip designed to penetrate radially into the outer circumference of the bone flap. The mandrel part is used for pre-fixation of the bone flap and the implant. For pre-fixation, the bone flap and the implant are inserted manually with the mandrel part away from the skull opening. For this, the mandrel tip is designed to penetrate radially into the bone flap. In this pre-fixed state, the bone flap and the implant together in the skull opening can be repositioned. The actual fixation takes place afterwards. In order to successfully penetrate the outer circumference of the bone flap, the mandrel tip projects beyond the first part along the transverse axis. In different configurations, the number of mandrel parts is different. A plurality of mandrel parts is advantageous in particular when the bone flap to be fixed is formed from a plurality of free bone fragments. These free bone fragments can be pre-fixed together to the implant by the mandrel parts.

[0015] In a further configuration of the invention, the mechanism comprises at least one clamping element and a conical element, the clamping element being mounted movably along a transverse axis and having an inner conical surface and an end surface forming a first or second part, the conical element being mounted movably along a longitudinal axis and having an outer conical surface interacting with the inner conical surface, the clamping element being displaceable along the transverse axis by movement of the conical element. The clamping element serves to transmit forces to the bone flap or to the surrounding skull, depending on whether the end surface forms the first or second part. The displacement of the clamping element along the transverse axis is caused by a longitudinal movement of the conical element. The inner and outer conical surfaces are inclined with respect to the longitudinal and / or transverse axes and are slidably mounted on each other. As a result, the longitudinal displacement of the conical element causes a lateral displacement of the clamping element. The conical element is preferably designed for direct or indirect manual actuation. As a result, the application of a force or torque required to displace the conical element along its longitudinal axis can be applied directly or indirectly to the conical element either manually or by using a tool suitable for this.

[0016] In a further configuration of the invention, the mechanism has a further clamping element, which is displaceable in the opposite direction along the transverse axis by the movement of the conical element. With regard to the basic function and configuration of the further clamping element, what has been said in connection with the clamping element applies. If the end face of the clamping element forms the first part, the end face of the further clamping element forms the second part, or vice versa. The clamping element and the further clamping element are preferably offset from each other by 180° in the circumferential direction of the implant.

[0017] In a further configuration of the invention, the conical element has a screw thread, which is screwed into a complementary mating thread for a screw-in movement along the longitudinal axis. The conical element can thus be moved like a screw along the longitudinal axis to transmit forces and movements to the clamping element. Preferably, the screw thread is an internal thread and the complementary mating thread is an external thread. The complementary mating thread is stationary relative to the longitudinal axis. Due to the mounting for screw-in movement, the application of a torque about the longitudinal axis results in a rotational displacement about the longitudinal axis and a translational displacement along the longitudinal axis. In other words, in this configuration, the conical element can be unscrewed in a direction towards the medial skull and / or screwed in a direction towards the lateral skull along the longitudinal axis. In an alternative configuration, instead of mounting the conical element for a screw-in movement, a mounting of the conical element for a latching movement is provided.

[0018] In a further configuration of the invention, the mechanism comprises a rotation axis oriented along the longitudinal axis and an eccentric element movably mounted about the rotation axis and having a contour eccentric with respect to the rotation axis, different parts of the contour forming a first part and a second part, and by rotation of the eccentric element the contour is clamped between the outer circumference of the bone flap and the inner circumference of the skull. The first and second parts are preferably arranged diametrically opposite each other on the eccentric element with respect to the rotation axis. In different configurations the eccentric contour has different shapes, for example, in the broadest sense, non-circular, elliptical, elongated, etc. The rotation axis is preferably oriented parallel to the longitudinal axis. Rotation of the eccentric element about the rotation axis causes the first and second parts to bear against the respective bone structures. Further rotation of the eccentric element causes the eccentric contour to press the first part radially against the bone flap on one side and the second part radially against the surrounding skull on the other side. As a result, the eccentric element is clamped within the annular gap, the radial space between the outer circumference of the bone flap and the inner circumference of the skull is enlarged in the area of ​​the eccentric element, and therefore the area of ​​the annular gap directly opposite the implant is reduced, and finally it is completely closed, establishing bone-to-bone contact between the bone flap and the surrounding skull.

[0019] In a further configuration of the invention, there is a shaft element, at one end of which an eccentric element is arranged and at the other end of which a tool engagement element is arranged, the tool engagement element being designed to apply a torque directed around a rotation axis. The shaft extends along a longitudinal axis, preferably parallel to the longitudinal axis. The tool engagement is arranged at a first end of the shaft element and the eccentric element is arranged at a second end of the shaft element. The eccentric element and the tool engagement element are connected to each other by the shaft element, so that a rotation of the tool engagement element results in a corresponding rotation of the shaft element and the eccentric element. In different configurations, the tool engagement element has a different shape and is designed for engagement of a tool. For example, the tool engagement element may have a hex socket, a hex head, a cross head slot or a slot.

[0020] In a further configuration of the invention, the tool engagement element forms the upper end of the implant with respect to the longitudinal axis and is connected to the shaft element via a predetermined break. The predetermined break breaks under the action of a defined mechanical load. This allows the tool engagement element to be sheared and / or broken in a defined manner from the shaft element after the fixation is completed. In this configuration, the structural height of the implant with respect to the longitudinal axis is reduced, since the tool engagement element forms the upper end of the implant. In particular, the tool engagement element does not remain permanently outside the bone skull after the fixation is completed, which would result in cosmetic, medical and / or other negative effects. The predetermined break is located between the tool engagement element and the shaft element with respect to the longitudinal axis. Compared to the shaft element, the predetermined break has a cross section with reduced load-bearing capacity. As a result, a single mechanical load generates locally high mechanical stresses in the area of ​​the predetermined break, which ultimately leads to local mechanical failure.

[0021] In a further configuration of the invention, the eccentric element has at least a first blade portion forming a first part and a second blade portion offset with respect to the axis of rotation forming a second part, each of the blade portions projecting radially from the axis of rotation with a longitudinal extent and with cutting edges facing opposite to each other. In this configuration of the invention, the eccentric element has an eccentric, elongated contour in the broadest sense. This contour is formed in part by the first blade portion and the second blade portion. When the eccentric element is clamped, the blade portions, more particularly their cutting edges, each penetrate the associated bone structure. In particular, the cutting edge of the first blade portion penetrates the outer periphery of the bone flap. The cutting edge of the second blade portion penetrates the inner periphery of the skull. As a result, a particularly secure fixation is achieved. In different configurations, the number of blade portions is different. For example, in one configuration, several blade portions are arranged in coplanar pairs one on top of the other with respect to the longitudinal axis.

[0022] In a further configuration of the invention, the mechanism comprises a pressure element and a spring element, the pressure element extending along a transverse axis between a first end face forming the first or second part and a second end face and being mounted movably along the transverse axis, the spring element being at least indirectly supported on the second end face, the pressure element being biased by the spring element with a spring force along the transverse axis. Depending on the orientation of the pressure element and the arrangement of the spring element, the first end face of the pressure element forms either the first or the second part. As a result, the pressure element can be pressed by the spring element against the bone flap or against the surrounding skull. The spring force of the spring element acts along the transverse axis. For fixation purposes, the pressure element can be displaced, for example manually, against the spring force along the transverse axis, so that the projected transverse space between the first and second parts can be reduced. After the prepositioning is completed, the manual pressure on the pressure element can be released, so that the spring presses the pressure element against the corresponding bone structure. In another configuration, the pressure element is releasably locked against a spring force at a rear end position relative to the transverse axis, after which the spring force presses the pressure element along the transverse axis against the corresponding bone structure.

[0023] In a further configuration of the invention, a locking element is present, which is displaceable relative to the pressure element between a locked position, in which the locking element fixes the pressure element against the spring force of the spring element relative to the transverse axis, and a released position, in which the pressure element is free to move along the transverse axis. The displacement of the locking element between the locked and released positions is preferably performed manually. In the locked position, a part of the locking element is removably form-fittably and / or pressure-fittably connected to a part of the pressure element. Displacement in the direction of the released position separates said connection between the locking element and the pressure element. After the connection is separated, the pressure element is free to move along the transverse axis, so that, depending on its configuration, the spring force presses the first end surface against the associated bone structure (bone flap or skull).

[0024] In a further configuration of the invention, the mechanism comprises a first tube element and a second tube element, the longitudinal axes of which are coaxial and extend parallel to the transverse axis, the first tube element having a profiled first tube side and a first surface forming the first part, and the second tube element having a complementary profiled second tube side and a second surface forming the second part, the first and second tube side being connectable to each other in different axial relative positions of the tube elements to form a form-fit and / or pressure-fit connection along the transverse axis. Different axial relative positions result in different transverse spaces between the first and second surfaces. In other words, the first and second tube elements are joined to each other along the transverse axis. In this case, the first tube element is inserted into the second tube element, the profiled first tube side being the outer side and the profiled second tube side being the inner side. In a further configuration, the second tube element is inserted into the first tube element, in which case the profiled first tube side is the inner side and the profiled second tube side is the outer side. In both cases, one of the two tube elements acts as a kind of bushing, and the remaining tube element acts as a kind of bolt, pin, etc. The profiles present on the tube sides can be latch-shaped or thread-shaped, respectively. Thus, in one configuration, the connection is a latch connection, and in a further configuration, it is a screw connection. In the latter configuration, the two tube elements are unscrewed from each other to widen the lateral space, but of course, they are not completely unscrewed from each other. In the latch connection configuration, they are latched on one side to widen the lateral space.

[0025] In a further configuration of the invention, the second surface is a surface of the end face of the second tube element, which is designed to bear radially against the inner circumference of the skull, and the first surface is an outer side surface of the first tube element, which is designed to be inserted into a radially extending bore at the outer circumference of the bone flap. In this configuration, the implant is firstly joined to the bone flap for the purpose of pre-fixation. For this purpose, the outer side surface of the first tube element is inserted into a radial bore provided in the bone flap. In this case, the first tube element can be inserted loosely, in a pressure-fit, form-fit and / or integral manner into the radial bore. Once the pre-fixation is completed, the skull bone flap with the implant can be placed in the skull opening. For the actual fixation, the two tube elements are displaced relative to each other along the transverse axis. This is done, for example, by the above-mentioned latch connection or screw connection. The relative displacement results in an expansion of the lateral space, so that the annular gap widens in the region of the implant and shrinks on the opposite side, eventually closing completely to form a bone-to-bone contact between the bone flap and the surrounding skull.

[0026] In a further embodiment of the invention, the first cylinder side is an outer side and the second cylinder side is an inner side. Thus, in this embodiment, the first cylinder element is inserted into the second cylinder element. To change the lateral space between the surfaces of the opposing end faces of the cylinder elements, i.e., between the first and second parts, the first cylinder element can be axially displaced further into or out of the second cylinder element.

[0027] In a further configuration of the invention, the first and second cylinder side surfaces each have a latch-shaped profile and are latched to one another along the transverse axis in such a way that one can be latched to the other on one side. The latch shape of the first cylinder side surface complements the latch shape of the second cylinder side surface and vice versa. By one can be latched to the other on one side, it is meant that the latch connection formed between the latch shapes always acts form-fittingly in one direction along the transverse axis, so that lateral movement in this direction is completely prevented. The latch connection can also be latched in the opposite direction, so that the two cylinder elements can be connected to one another in different axial relative positions.

[0028] In a further configuration of the invention, the first barrel side and the second barrel side each have a thread-shaped profile and are threadedly engaged with one another for threaded movement along the transverse axis.

[0029] The invention also relates to an implant system comprising at least two implants according to the above description. [Brief description of the drawings]

[0030] Further advantages and features of the present invention will become apparent from the following description of preferred exemplary embodiments of the invention, as illustrated by the claims and the drawings. [Figure 1] FIG. 2 is a schematic, highly simplified perspective view of a patient's head with a bone flap closing a cranial opening in the patient's skull. [Diagram 2] 2 is a schematic simplified cross-sectional view of the skull according to FIG. 1 in the region of the skull opening, the bone flap not being shown. [Diagram 3] FIG. 3 shows the area of ​​FIG. 2 with the bone flap superimposed. [Figure 4] FIG. 4 shows the area indicated by FIGS. 2 and 3 with one embodiment of an implant according to the invention for fixing a bone flap in a cranial opening. [Diagram 5] FIG. 2 is a schematic perspective view of a further embodiment of an implant according to the invention; [Figure 6]6 is a schematic diagram of the implant according to FIG. 5 in longitudinal section. [Figure 7] Schematic diagram of the implant according to Figs. [Figure 8] 8 is a schematic side view of the implant according to FIGS. 5 to 7. FIG. [Figure 9] FIG. 9 is a further side view of the implant according to FIGS. 5 to 8 rotated by 90°. [Figure 10] FIG. 10 is a schematic, highly simplified representation of a first intraoperative situation using an implant according to FIGS. 5 to 9 . [Figure 11] FIG. 10 shows a second intraoperative situation using the implant according to FIGS. 1 to 9 . [Figure 12] FIG. 12 shows the second intraoperative situation according to FIG. 11 in a schematic cross-sectional view along section XII-XII. [Figure 13] FIG. 10 is a schematic perspective view of a first variant of the implant according to FIGS. 5 to 9 . [Figure 14] FIG. 10 is a schematic perspective view of a second variant of the implant according to FIGS. 5 to 9 . [Figure 15] FIG. 10 is a schematic cross-sectional view of a third variant of the implant according to FIGS. 5 to 9 . [Figure 16] FIG. 10 is a schematic side view of a fourth variant of the implant according to FIGS. 5 to 9 . [Figure 17] 3 is a schematic perspective view of a further embodiment of an implant according to the invention; FIG. [Figure 18] 18 is a schematic side view of the implant according to FIG. 17 . [Figure 19] FIG. 19 is a further side view of the implant according to FIGS. 17 and 18 rotated by 90°. [Figure 20] 19 in longitudinal section, FIG. [Figure 21] Enlarged detail view of region XXI of the implant according to Figs. 17 to 20. [Figure 22] FIG. 22 shows an intraoperative situation using the implant according to FIGS. 17 to 21 . [Diagram 23] FIG. 22 is a schematic perspective view of a first variant of the implant according to FIGS. 17 to 21 . [Figure 24]FIG. 22 is a schematic perspective view of a second variant of the implant according to FIGS. 17 to 21 . [Diagram 25] 22 a schematic perspective view of a third variant of the implant according to figures 17 to 21, individual components and / or parts of the implant not shown. [Figure 26] FIG. 22 is a schematic perspective view of a fourth variant of the implant according to FIGS. 17 to 21 . [Figure 27] FIG. 22 is a schematic perspective view of a fifth variant of the implant according to FIGS. 17 to 21 . [Figure 28] FIG. 22 is a schematic perspective view of a sixth variant of the implant according to FIGS. 17 to 21 . [Figure 29] Schematic diagram of a sixth variant of the implant according to FIGS. 17 to 21 . [Diagram 30] FIG. 2 is a schematic perspective view of a further embodiment of an implant according to the invention; [Diagram 31] Schematic diagram of an implant according to FIG. 30. [Diagram 32] Schematic diagram of a longitudinal section of an implant according to FIG. 30 and FIG. 31 . [Diagram 33] FIG. 12 is a cross-sectional view corresponding to FIG. 12 of an intraoperative situation using an implant according to FIGS. 30 to 32. [Diagram 34] FIG. 33 is a schematic, partially transparent perspective view of a first variant of the implant according to FIGS. 30 to 32. [Diagram 35] FIG. 33 is a schematic, partially transparent perspective view of a second variant of the implant according to FIGS. 30 to 32. [Diagram 36] FIG. 2 is a schematic perspective view of a further embodiment of an implant according to the invention, having a first barrel element and a second barrel element; [Figure 37] FIG. 37 is a schematic perspective view of a first barrel element of the implant according to FIG. 36. [Figure 38] FIG. 37 is a schematic perspective view of the second barrel element of the implant according to FIG. 36. [Figure 39] Schematic diagram of a longitudinal section of an implant according to FIG. 36. [Diagram 40] FIG. 39 is a schematic perspective view of a modified second cylinder element according to FIG. 38; [Diagram 41]FIG. 40 is a schematic, highly simplified intraoperative view of the implant according to FIGS. 36 to 39 . [Diagram 42] FIG. 40 is a schematic, highly simplified side view of a first variant of the implant according to FIGS. 36 to 39 . [Diagram 43] FIG. 40 is a schematic, highly simplified side view of a second variant of the implant according to FIGS. 36 to 39 . [Diagram 44] FIG. 40 is a schematic side view of a third variant of the implant according to FIGS. 36 to 39 . [Diagram 45] FIG. 40 is a schematic side view of a fourth variant of the implant according to FIGS. 36 to 39 . [Figure 46] FIG. 40 is a schematic diagram showing a further intraoperative situation using the implant and pin according to FIGS. 36 to 39 . [Figure 47] 47 is a schematic perspective view of the pin according to FIG. 46. [Figure 48] FIG. 48 is a schematic perspective view of a variant of the pin according to FIG. 47; Detailed Description of the Invention

[0031] According to Figure 1, the patient's head has a skull opening B, which extends from an outer bone surface CA through the patient's skull C to an inner skull surface CI (Figure 2). The skull opening B extends through the skull C along its axial direction A. The skull opening B is surrounded by the skull K along its radial direction R.

[0032] A skull opening may in principle be caused by an accident or some other unintended action. In the present case, skull opening B is the result of a craniotomy and serves as a surgically created entrance for a neurosurgical procedure on the patient's brain.

[0033] During such a craniotomy, the skull C is opened by mechanically separating the bone flap D. This can be performed, for example, by trepanation. Here, the bone flap D is separated from the skull C to form an annular gap S. The annular gap S is also called the craniotomy gap. The bone flap D may also be called a bone part, bone fragment or bone segment.

[0034] After the bone flap D has been separated, it may be temporarily removed from the remainder of the skull to form the actual skull opening B. After the procedure on the brain is completed, the bone flap D is repositioned and fixed in opening B.

[0035] 4, an implant 100 is provided for securing a skull flap D in a skull opening B. The implant 100 has a longitudinal axis X, a transverse axis Y, a first portion 101, a second portion 102 and a mechanism 103.

[0036] The longitudinal axis X extends along an axial direction A of the skull opening B. The transverse axis Y, oriented perpendicular to the longitudinal axis X, extends along a radial direction R of the skull opening B. The above arrangement of the longitudinal axis X and the transverse axis Y relates to the configuration shown in FIG. 4, in which the bone flap D is secured by the implant 100.

[0037] The first portion 101 is designed to transmit forces to the bone flap D. Therefore, the first portion 101 faces towards the bone flap D.

[0038] The second portion 102 is designed to transmit forces to the skull K surrounding the skull opening B. The second portion therefore faces towards the skull K.

[0039] The mechanism 103 is operably connected to the first part 101 and the second part 102 and is designed to change the lateral space Q between the first part 101 and the second part 102, projected on the lateral axis Y. As a result of the expansion of the lateral space Q, the first part 101 can be pressed radially inwardly against the bone flap D and the second part 102 can be pressed radially outwardly against the skull K. The transmission of forces between the first part 101 and the bone flap D on one side and between the second part 102 and the skull K on the other side is performed along the radial direction R, which can therefore also be called radial fixation.

[0040] To fix the bone flap D, the implant 100 is introduced into the annular gap S along the axial direction A. The first part 101 is oriented radially R inwards, i.e. towards the bone flap D. The second part 102 is oriented radially R outwards, i.e. towards the skull K. After this, the mechanism 103 is actuated in order to enlarge the lateral space Q. This actuation can be performed directly or indirectly, with the aid of a tool or purely manually. The actuation of the mechanism causes the above-mentioned enlargement of the lateral space Q. The enlargement of the lateral space Q causes the first part 101 to act radially R inwards relative to the bone flap D and, conversely, the second part 102 to act radially R outwards relative to the bone flap K. As a result, the annular gap S is enlarged locally, i.e. in the region of the implant 100. This local enlargement of the annular gap S necessarily leads to a local reduction of the annular gap S on the side of the bone flap D diametrically opposite the implant 100 in the radial direction R. In this region, the bone flap D is pressed against the skull K by the action of the radial direction R of the implant 100. This establishes bone-to-bone contact and fixes the bone flap D in the opening B by being clamped in the radial direction R.

[0041] In principle, a single implant is sufficient for fixation. However, it is self-evident that multiple implants can also be used. In this case, they are circumferentially spaced apart from one another in the annular space S. The multiple implants are then radially clamped between the bone flap D and the surrounding skull K by the expansion of their projected lateral space Q. Fixation with multiple implants will be described in more detail later.

[0042] In different embodiments, the mechanism takes different forms. A great variety of structures are conceivable for enlarging the lateral space Q, i.e. for generating a spreading or spreading apart movement between the two parts. For example, mechanisms based on the screw or thread principle, scissor joint mechanisms, wedges, cones and / or clamping mechanisms, latch mechanisms, eccentric mechanisms, etc. are conceivable. In this case, the enlargement of the lateral space Q brought about by the mechanism can be based on a translational and / or rotational displacement of the first and / or second part. For example, the first part may be displaced radially inwards along the transverse axis Y while the second part is stationary with respect to the transverse axis Y, or vice versa. The same applies mutatis mutandis to a rotational displacement about the longitudinal axis X.

[0043] The transmission of forces between the two parts and the respective associated bone structures, i.e. the bone flap D on one side and the skull K on the other side, can be direct or indirect. Direct means that a direct contact is established between the respective part and the corresponding bone structure. Indirect means that further components or elements of the implant can be placed between the respective part and the respective associated bone structure D, K.

[0044] Here, the force can be transmitted to the bone flap D in part via its outer periphery DA. Alternatively or additionally, the force can be transmitted via a bore H formed in the bone flap D, as shown by the dashed line in FIG. 4. The same applies to the transmission of the force to the skull K. This means that the force can be transmitted in part to the inner periphery KI of the skull K. It is basically also conceivable to provide the skull K with a bore or the like in the radial direction R in order to transmit the force.

[0045] In the case of the implant 100 according to FIG. 4, the forces are transmitted directly to the respective circumferential surfaces of the bone structure. The first part 101 consequently has a first contact surface 104, which is designed to bear radially (directly) against the outer periphery DA of the bone flap D. The second part 102 has a second contact surface 105, which is designed to bear radially (directly) against the inner periphery KI of the skull K. The unlabeled normal direction of the first contact surface 104 is in this example parallel to the transverse axis Y, pointing radially inwards. The unlabeled normal direction of the second contact surface 105 is in this example parallel to the transverse axis Y, pointing radially outwards. The contact surfaces 104, 105 are consequently oriented opposite each other.

[0046] 4, the first part 101 has a joint surface 106. The joint surface 106 is particularly useful when the bone flap D has a bore H. In this case, the part 101, more particularly the joint surface 106, can be inserted into the bore H. In this case, forces are transmitted via the unlabeled wall of the bore H, and not via the periphery DA.

[0047] In the case of the implant 100 according to Fig. 4, the first part 101, the second part 102 and the mechanism 103 are entirely arranged in the annular gap S. The entire implant 100 is arranged in the radial direction R, and thus in the transverse direction Y, between the outer periphery DA of the bone flap D and the inner periphery KI of the skull K. The entire implant 100 is arranged in the axial direction A, and thus in the longitudinal axis X, between the outer skull surface CA and the inner skull surface CI. As a result, the implant 100 does not protrude upwards or downwards from the annular gap S along the longitudinal axis X.

[0048] 5 to 16 show a further embodiment of an implant 200 according to the invention, while FIGS. 13 to 16 relate to a variant of this embodiment.

[0049] 5-9, implant 200 has a longitudinal axis X, a transverse axis Y, a first portion 201, a second portion 202, and a mechanism 203. Mechanism 203 has a conical segment 207, a first clamping element 208, and a second clamping element 209.

[0050] The two clamping elements 208, 209 are each mounted for movement along a transverse axis Y.

[0051] The first clamping element 208 has a first inner conical surface 210 and a first end surface 211. The first inner conical surface 210 is medial with respect to the longitudinal axis X, and the first end surface 211 is correspondingly lateral. The first end surface 211 is designed to bear radially against the outer periphery DA of the bone flap D and in this respect functions as a first contact surface 204. The first clamping element 208 and / or its first end surface 211 thus form the first part 201 of the implant 200.

[0052] The second clamping element 209 has a second inner conical surface 212 and a second end surface 213. The second end surface 213 is external and the second inner conical surface 212 is internal with respect to the longitudinal axis X. The second end surface 213 is designed to bear radially against the inner circumference KI of the skull K and thus serves as the second contact surface 205. The second clamping element 209 and / or its second end surface 213 thus form the second part 202 of the implant 200.

[0053] The conical element 207 is mounted movably along a longitudinal axis X and has an outer conical surface 214 which slidably interacts with the two inner conical surfaces 210, 212. The conical element 207 is displaceable relative to the longitudinal axis X between an upper end position, not shown, and a lower end position (FIG. 6). In the upper end position, the two clamping elements 208, 209 are displaced inwards relative to the longitudinal axis, towards each other along a transverse axis Y. Thus, in the upper end position, there is a first transverse space, not shown in more detail, between the first contact surface 204 and the second contact surface 205. A longitudinal displacement of the clamping element 207 in the direction from the upper end position towards the lower end position (FIG. 6) has the effect of displacing the clamping elements 208, 209 outwards along the transverse axis Y with an increase in the transverse space Q. In the process, the longitudinal movement of the conical element 207 is converted into a lateral movement of each of the clamping elements 208, 209 through the interaction of the outer conical surface 214 with the two inner conical surfaces 210, 212. The transmission ratio can be modified structurally by adapting the inclination or cone angle of each of the conical surfaces 210, 212, 214.

[0054] The implant 200 of this embodiment has a housing 215 for receiving and / or movably mounting two clamping elements 208, 209. The housing 215 has the shape of a hollow cylinder with a circular cross section and is provided on both sides in the lateral direction Y with unnumbered receiving openings into which the clamping elements 208, 209 are introduced. The receiving openings may also be called pockets.

[0055] In the illustrated embodiment, the conical element 207 is mounted for threaded movement along the longitudinal axis X. For this purpose, the conical element 207 has a thread 216 which is screwed into a complementary, stationary counter-thread 217. In this case, the thread 216 is an internal thread. The counter-thread 217 is correspondingly an external thread. In the illustrated embodiment, the counter-thread 217 is formed on a threaded rod 218 having a longitudinal axial extension parallel to the longitudinal axis X, more specifically coaxial therewith. The threaded rod 218 is fixed at its lower end, relative to the longitudinal axis X, to the housing 215.

[0056] In the embodiment shown, the conical element 207 is designed to be subjected to forces and / or torques by a suitable tool and has a corresponding tool engagement 219. The tool engagement 219 is recessed from the unnumbered upper surface of the conical element 207 along the longitudinal axis X and has a cylindrical cross-sectional shape in this example. The tool engagements 219 are circumferentially offset from one another by 180°.

[0057] To spread the two clamping elements 208, 209 apart, i.e. to enlarge the (projected) lateral space, said tool is detachably connected to the tool fitting 219 and a torque directed about the longitudinal axis X is applied. Under the action of the torque, the conical element 207 can be screwed downwards along the threaded rod 218, so that the clamping elements 208, 209 move out of the housing 215 and at this point spread apart.

[0058] In the illustrated embodiment, the implant 200 also has a support part 220, which is arranged along the longitudinal axis X above the two clamping elements 208, 209 and the conical element 207. In this respect, the support part 220 is arranged above the first part 201 and the second part 202. The support part 220 has a lower surface 221, which is designed to support the implant 200 on the one side against the outer surface KF of the skull K and on the other side against the outer surface DF of the bone flap D (see FIG. 2). The lower surface 221 is oriented perpendicular to the end surfaces 211, 213. The support part 220 facilitates the positioning of the implant 200 in the annular space S. This support part avoids excessively deep penetration into the annular space S and the associated risks, such as irritation related to the pressure of the dura, which may in the worst case involve an epidural hematoma.

[0059] In the illustrated embodiment, the support 220 is connected to the rest of the implant 200 by a removable joint connection means, more specifically a bayonet fastening. In this case, the bayonet fastening is formed between the unnumbered inner circumference of the support 220 and the shape of the upper surface of the housing 215. Instead of the bayonet fastening, for example a conventional screw connection or the like can also be provided. Alternatively, a plug-type mounting connection or a latch connection is also conceivable. The removable joint connection allows the support 220 to be separated and removed from the housing 215 after the fixation has been completed. After the removal of the support 220, the (remaining part of) the implant 200 is entirely located in the annular gap S with respect to the longitudinal direction X. This has cosmetic and medical advantages.

[0060] In the illustrated embodiment, the support 220 is disc-shaped and has two tool fittings 222 circumferentially offset from each other by 180° for mounting a tool for removing and / or connecting said bayonet fastening. The tool fittings 222 may alternatively or additionally be used as bore holes for pre-fixing the implant 200 to the bone flap D.

[0061] In this embodiment, the implant 200 also has a mandrel part 223. The mandrel part 223 extends along the transverse axis Y and has at one end a mandrel tip 224 which projects beyond the first part 201, i.e. in this embodiment the first clamping element 208. This mandrel tip is designed to penetrate radially into the outer periphery DA of the bone flap D. The mandrel part 223 is fixed to the housing 215 at its end remote from the mandrel tip 224 in a manner not shown in more detail. The mandrel part 223 serves to pre-fix the implant 200 to the bone flap D. For this purpose, the mandrel tip 224 penetrates radially into the bone flap D. This is preferably done before the bone flap D is repositioned in the opening B.

[0062] 10 to 12 show a first (FIG. 10) and a second (FIGS. 11 and 12) intraoperative situation with the implant 200. The first intraoperative situation shows the state before fixation of the bone flap D, and the second intraoperative situation shows the final fixation. The illustrated example situation contemplates the use of several structurally identical implants, specifically the implant 200, the second implant 200' and the third implant 200'', which form an implant system. In this example, the implants 200, 200', 200'' are arranged in the annular gap S so as to be offset by about 120° in the circumferential direction of the bone flap D. For the purpose of pre-fixation, the mandrel part of each of the implants 200, 200'', 200'' is inserted into the outer circumference DA of the bone flap D in the manner already described. After the implants 200, 200', 200'' have been inserted into the bone flap D or inserted and attached to the bone flap D, the previously fixed arrangement at this point is (re)positioned together in the skull opening B. After this, the situation illustrated in FIG. 10 is reached.

[0063] For the actual fixation, in the illustrated example the first implant 200 is expanded, i.e. its clamping elements 208, 209 are spread apart in the radial direction R of the opening B via the actuation of the already described conical element 207. As a result, the bone flap D is pressed against the surrounding skull K on the side of the opening B diametrically opposite the first implant 200. The further implants 200', 200'' serve in this example as an additional fixation in the broad sense.

[0064] In all other respects, Figures 11 and 12 show that the support portions of each of the implants 200, 200', 200'' are removed after fixation is complete, so that the implants 200, 200', 200'' do not protrude above the outer skull surface CA.

[0065] It is also evident with reference to FIG. 11 that the first contact surface 204 of the first clamping element 208 and the second contact surface 205 of the second clamping element 209 are curved. The same applies to the further implants 200′, 200″. Said curvature makes it possible to establish contact as far as possible over the entire surface area and therefore to transmit the greatest possible contact forces.

[0066] In the situation shown in FIG. 11, the implants 200, 200′, 200″ are each placed in a portion of the annular gap S, called a borehole. The boreholes are typically created during a drilling procedure and connected to one another using a tool suitable for this purpose. This connection of the boreholes forms the actual annular or drilling gap S. The radius of curvature of the contact surfaces 204, 205 corresponds in this embodiment to the radius of the boreholes, respectively. The radius of curvature of the contact surfaces 204, 205 varies depending on the embodiment and is in the range of 6 to 20 mm.

[0067] 13 to 16 show variants of the implant 200 according to Figs. 5 to 9. Their functions and / or structures are substantially identical to those of the implant 200. Therefore, to avoid repetition, only the important differences between the variants are described below. Functionally identical components and / or parts are not described separately. Instead, explicit reference is made to the content disclosed in connection with the implant 200.

[0068] The implant 200a differs in the shape of the clamping element. Its end faces 211a, 213a are each provided with a profile 225a, which serves to increase the respective contact surface area. The profile 225a extends parallel to the longitudinal axis X and has a number of grooves recessed radially inwards on the respective end face 211a, 213a. It goes without saying that different shapes of the profile 225a are also conceivable. In a variant not shown, the profile is formed by a honeycomb, spikes or a roughened surface in the broadest sense.

[0069] To reduce weight, the clamping elements of the implant 200a also have respective clearances 226a, which may also be referred to as pockets, that are recessed inwardly of the respective clamping elements along the transverse axis Y from the end faces 211a, 213a, respectively.

[0070] In contrast, the implant 200b according to Fig. 14 has only one clamping element 209b. In this variant, the edge region of the housing 215b that is located opposite the second clamping element 209b along the transverse axis Y acts as the first part 201b.

[0071] The implant 200c according to Fig. 15 comprises two mandrel parts 223c which project outwards opposite one another along the transverse axis Y. The variant with two mandrel parts 223c is particularly advantageous when the bone flap is made up of several, in particular fragmented, segments. The segments or fragments which form the bone flap can be "put back together like a jigsaw puzzle" so to speak, using the mandrel parts 223c.

[0072] In the variant according to Fig. 16, the implant 200d has, in turn, a first clamping element 208d and a second clamping element 209d. In this variant, the clamping elements 208d, 209d are manufactured from a plastically deformable mass, which is laterally extruded from the housing of the implant 200d under the action of a conical element. The plastically deformable mass may be a type of putty or the like.

[0073] It will be appreciated that the features of implant 200 and the features described with respect to implants 200a, 200b, 200c, 200d can be combined to provide additional combinations of features not shown in the figures.

[0074] 17 to 29 show a further embodiment of an implant 300 according to the invention, while FIGS. 23 to 29 relate to a variation of this embodiment.

[0075] The implant 300 has a longitudinal axis X, a transverse axis Y, a first portion 301, a second portion 302, and a mechanism 303. The first portion 301 is likewise designed to transmit forces to the bone flap D. The second portion 302 is thus designed to transmit forces to the skull K.

[0076] The mechanism 303 is designed for rotational displacement of the first part 301 and the second part 302, in contrast to the embodiments and / or variants described above.

[0077] The mechanism 303 has a rotation axis G and an eccentric element 308 .

[0078] In the embodiment shown, the axis of rotation G is an axis in the geometric sense, oriented parallel to the longitudinal axis X, more specifically coaxial therewith.

[0079] The eccentric element 308 is movably mounted with respect to the axis of rotation G and has a contour 311 eccentric with respect to the axis of rotation G. Different parts of the eccentric contour 311 form the first part 301 and the second part 302. Rotation of the eccentric element 308 about the axis of rotation G results in a change of the lateral space projected on the lateral axis Y between the first part 301 and the second part 302. As a result, the eccentric element 308, more specifically its contour 311, can be clamped in the annular gap S via rotation about the axis of rotation G, so that the first part 301 is radially pressed against the bone flap D and the second part 302 is radially pressed against the skull K.

[0080] The two parts 301, 302 project outwardly in opposite directions from the axis of rotation G. It goes without saying here that the shape of the contour 311 shown in particular in Figures 17 to 19 is purely exemplary. All that is essential is the eccentricity of the contour 311, i.e. that the contour 311 is not rotationally symmetrical with respect to the axis of rotation G.

[0081] In the illustrated embodiment, the implant 300 also has a shaft element 307 that extends linearly along a rotation axis G between an unlabeled first end and an unlabeled second end. An eccentric element 308 is disposed at the second end of the shaft element 307 and fixedly connected thereto. A tool mating element 319 is disposed at the first end and fixedly connected to the shaft element 307.

[0082] The tool mating element 319 is designed to apply torque about the axis of rotation G, and in the illustrated embodiment is a hex socket.

[0083] In the illustrated embodiment, the tool mating element 319 forms an upper end surface relative to the longitudinal axis X of the implant 300. The eccentric element 308 forms a lower end surface in this respect.

[0084] The implant 300 has a plate-shaped support part 320, similar to the implant 200. The function of the support part 320 is substantially similar to that of the support part 220, so that in order to avoid repetition, explicit reference is made to the contents disclosed in this regard.

[0085] The implant 300 also has two mandrel parts 323, each of which is provided at one end with a mandrel tip 324. At the other end, each of the mandrel parts 323 is fixedly connected to the support part 320. In terms of its function and construction, the mandrel parts 323 are substantially identical to the mandrel part 223 of the implant 200. In this regard, reference is made explicitly to what has been said above.

[0086] The shaft element 307 is attached to the support 320 so as to be capable of relative rotation. Furthermore, the shaft element 307 is form-fittingly fixed with the eccentric element 308 and the tool engagement element 319 on the support 320 with respect to the longitudinal axis X. For this purpose, the support 320 is formed with a through hole (not shown) extending from the upper surface to the lower surface of the support 320.

[0087] In the embodiment shown, the eccentric element 308 has a first blade portion 309 and a second blade portion 310. The first blade portion 309 forms, so to speak, the first portion 301. The second blade portion 310 forms, so to speak, the second portion 302.

[0088] In this example, the first blade portion 309 has a first cutting edge 312 and the second blade portion 310 has a second cutting edge 313. The cutting edges 312, 313 are oriented in opposite directions to each other.

[0089] When the eccentric element 308 is clamped in the annular gap S, the blade portions 309, 310, with their respective cutting edges 312, 313, penetrate the respective associated bone structure, i.e. the bone flap D or the skull K. The penetration by the cutting edges 312, 313 improves fixation.

[0090] In the illustrated embodiment, the tool mating element 319 is connected to the shaft element 307 via a predetermined break 317 (see FIG. 21 ). The predetermined break 317 has a cross-section with a reduced load-bearing capacity relative to the shaft element 307. As a result, after fixation is completed, the tool mating element 319 can be sheared off and removed from the shaft element 307 in a defined manner by application of additional torque. This prevents the implant 300 from protruding excessively from the annular space S of the outer skull surface CA. This provides cosmetic and medical benefits.

[0091] Figure 22 shows an intraoperative situation using implant 300, where a multi-implant system is used, which is made up of a number of structurally identical implants 300, 300', 300''. In all other respects, in order to avoid repetition, reference is made to the explanations given in relation to Figures 10 to 12, which are also applicable to Figure 22.

[0092] 23 to 29 show different variants 300a to 300f of the implant 300. The structure and function of these variants are substantially identical to the implant 300. Functionally identical components and / or parts will not be described separately. Instead, explicit reference is made to the present disclosure related to the implant 300.

[0093] The implant 300a differs in the configuration of the tool fitting 319a, which is designed to fit a driver. In this respect, it can also be called a slot. In contrast to the tool fitting 319, the tool fitting 319a does not protrude beyond the support with respect to the longitudinal axis X.

[0094] The implant 300b according to Fig. 24 differs firstly in the absence of a mandrel section and secondly in the configuration of the eccentric element 308b. In the case of the implant 300b, the support part 320b is provided with bore holes 322b for pre-fixation. The bore holes 322b extend from the upper to the lower surface of the support part 320b. For the purpose of pre-fixation, the support part can be pre-fixed to the bone flap D by means of a screw that extends through one of the bores 322b.

[0095] The eccentric element 308b has a plurality of first blade sections and a plurality of second blade sections, which are arranged one above the other with respect to a longitudinal axis X in the direction from the second end to the first end of the shaft element. In this respect, they can also be referred to as a lower first blade 309a, an intermediate first blade 309a' and an upper first blade 309a''. The eccentric element 308b therefore has a lower second blade 310a, an intermediate second blade 310a' and an upper second blade 310a''. It goes without saying that instead of the three blade pairs in this embodiment arranged on top of each other, there can be more or fewer blade pairs.

[0096] In the variant according to Fig. 25, only one component of the implant 300c is shown, in particular the shaft element 307c. To prevent the shaft element 307c from inadvertently rotating together with the eccentric element about the axis of rotation G in the direction opposite to the fixed direction, the shaft element 307c has a thread 325c in the region of its first end. The thread 325c is screwed into a counter-thread formed on the support, which is not shown in detail in the drawings. This counter-thread may, for example, be in the form of a locking nut or the like.

[0097] In the variant according to FIG. 26, the implant 300d has a spring element 326d instead of a tool fitting for applying a torque. The spring element 326d is fixed at one end to a first fastening part 327d and at the other end to a second fastening part 328d. The first fastening part 327d is assigned to and fixedly connected with the support part 320d. The second fastening part 328d is assigned to and fixedly connected with the shaft element 307d. In the configuration shown by FIG. 26, the spring element 326d is biased and applies a torque about the longitudinal axis X to the shaft element 307d. There is now a locking device, not shown in detail in the drawings, which keeps the shaft element 307d in the biased state. This locking device is transferable between a first state and a second state. In the first state of the locking device, the shaft element 307d is rotationally fixed with respect to the support part 302d. In the second state, it is allowed to move in rotation. After being allowed to move in rotation, the spring element 326d causes the shaft element 307d, and thus the eccentric element 308d, to rotate about the axis of rotation G. This clamps and / or forces the eccentric element 308d into the annular gap S.

[0098] In contrast to the implant 300 and the previous variants 300a to 300d, in the variant according to FIG. 27, the implant 300e has a torque-resistant connection between the support 320e and the shaft element 307e. As a result, the support 320e and the shaft element 307e always rotate together about the rotation axis G. The support 320e and the shaft element 307e may be connected by force fitting, by form fitting and / or integrally. Integral continuous designs are also conceivable. In the case of the implant 300e, the tool fitting 319e is fixedly arranged on the upper surface of the support 320e.

[0099] In the variant according to figures 28 and 29, the implant 307f has a corresponding borehole design based on the cavity-socket principle.

[0100] Figures 30 to 35 show a further embodiment of an implant 400 according to the invention, with Figures 34 and 35 relating to a variation of this embodiment.

[0101] 30-32, implant 400 has a longitudinal axis X, a transverse axis Y, a first portion 401, a second portion 402 and a mechanism 403. As shown in FIG.

[0102] Regarding the orientation of the longitudinal axis X and the transverse axis Y relative to the axial direction A and the radial direction R of the skull opening B, what was said in connection with the previous embodiment applies.

[0103] The first portion 401 is similarly designed to transmit a force to the bone flap D. The second portion 402 is correspondingly designed to transmit a force to the skull K. A mechanism 403 is operatively connected to the first portion 401 and the second portion 402 in a manner that will be described in more detail, and allows for altering the lateral space between these two portions.

[0104] Specifically, the mechanism includes a pressure element 408 and a spring element 407 .

[0105] The pressure element 408 extends along a transverse axis Y between a first end surface 409 and a second end surface 410. Furthermore, the pressure element 408 is mounted so as to be movable along the transverse axis Y.

[0106] The spring element 407 is supported at one end against a second portion 410 of the pressure element for force transmission. At the other end, the spring element 407 is at least indirectly operatively connected to the first portion 401. In the illustrated embodiment, the pressure element 408, and more particularly its first end surface 409, forms the second portion 402 and / or functions as the second contact surface 405.

[0107] The spring element 407 serves to bias the pressure element 408 along a transverse axis Y. The pressure element 408 is pushed outwardly along the transverse axis Y, in a radial direction R, by said bias, and thus can be pressed against the skull K (see FIG. 33).

[0108] Figures 30 to 32 show an outer end position of the pressure element 408, in which the pressure element 408 is displaced outwardly by application of a force under the action of the spring element 407 along the transverse axis Y. In an inner end position, not shown in the figures, the pressure element 408 is displaced inwardly along the transverse axis Y, and the spring element 407 is pressed along its axial direction and is thereby biased.

[0109] To lock said bias, a locking element 417 is provided in this embodiment. The locking element 417 can be displaced relative to the pressure element 408 between a locked position and a released position. In the locked position, the pressure element 408 is fixed with respect to the transverse axis Y by the locking element 417 countering the spring force of the (biased) spring element 407. In the released position, the pressure element 408 is free to move and thus the spring element 407 can displace the pressure element 408 in a direction towards the outer end position.

[0110] In the illustrated embodiment, the locking element 417 extends along a longitudinal axis X between a first end face 418 and a second end face 419. The second end face 419 has a form-fitting portion 422 which interacts in a form-fitting manner with a complementary form-fitting portion 427 of the pressure element 408 in the locked position along the transverse axis Y. In the illustrated embodiment, the form-fitting portion 422 is a protrusion protruding from the second end face 419 along the longitudinal axis X. The complementary form-fitting portion 427 is thus a recess formed in the pressure element 408 along the longitudinal axis X. In the locked position, the protrusion is inserted into the recess, so that the pressure element 408 is form-fittingly held on the locking element 417 in the transverse direction.

[0111] For displacement into the release position, the locking element 417 is displaced axially and upwards relative to the drawing plane of FIG. 32. As a result, the form-fitting portion 422 is pulled out of the complementary form-fitting portion 427. In the illustrated embodiment, the locking element 417 can be completely removed after displacement into the release position (see FIG. 33). Here, the locking element 417 is intended for manual actuation. For displacement in the direction towards the release position, an operator can grip the locking element 417 in the region of the first end face 418, for example between the thumb and index finger of one hand.

[0112] For pre-fixation purposes, the implant 400 has a mandrel portion 423 having a mandrel tip 424. The function and configuration of the mandrel portion 423 is substantially the same as in the previous embodiment, and therefore what was said there also applies in this embodiment.

[0113] There is also a support 420 for support on the outer skull surface CA. Its lower surface 421 bears both on the outer surface DF of the bone flap D and on the outer surface KF of the skull, for the purpose of positioning the implant 400 in the annular space S. In all other respects explicit reference is made to what has been said in connection with the supports 220, 320 of the previous embodiment.

[0114] In the embodiment shown, the implant 400 also comprises a housing 415. The housing 415 in this example serves, inter alia, to receive and / or mount the spring element 407, the pressure element 408 and the locking element 417. Furthermore, the first portion 401 is arranged and / or formed on a side of the housing 415 diametrically opposite the first end surface 409 along the transverse axis Y. This portion of the housing 415 serves in this respect as the first contact surface 404.

[0115] The housing 415 in this embodiment has a first receiving clearance 428 and a second receiving clearance 429 .

[0116] The first receiving clearance 428 extends along the transverse axis Y and serves to receive the spring element 407 and the pressure element 408. In the illustrated embodiment, the first receiving clearance 428 has a tubular, more particularly cylindrical, cross section. The shape of the pressure element 408 is adapted thereto and is accordingly complementary tubular, more particularly cylindrical. The first receiving clearance 428 is closed at one end and open at the other end. The pressure element 408 protrudes through an unlabelled opening at the other end of the first receiving clearance 428. The pressure element 408 is guided in the first receiving clearance 428 in a slidable manner along the transverse axis Y. The spring element 407 is supported at one end of the first receiving clearance 428 on an unlabelled wall of the housing 415. This wall forms, so to speak, the first part 401.

[0117] The second receiving clearance 429 extends from an upper surface of the support 420 into the first receiving clearance 428 along the longitudinal axis X. The second receiving clearance 429 serves to receive the second end 419 of the locking element 417. In this respect, the locking element 417 is slidably guided along the longitudinal axis X in the second receiving clearance 429.

[0118] The first receiving clearance 428 may also be referred to as a radial bore.

[0119] The second receiving clearance 429 may also be referred to as an axial bore.

[0120] In the illustrated embodiment, the mandrel portion 423 and the support portion 420 are integrally formed on the housing 415. It will be appreciated that alternatively, the above portions may be in the form of separate pieces.

[0121] In the embodiment shown, the housing 415 also has a cylindrical basic shape with its axial direction extending parallel to the longitudinal axis X. Due to the cylindrical configuration of the housing 415, the first portion 401 is correspondingly convexly curved, which improves the contact with the outer periphery DA of the bone flap D.

[0122] Figure 33 shows an intraoperative situation with implant 400, in which the bone flap D is already fully fixed. This is done with at least one further structurally identical implant 400'. To avoid repetition, reference is made to what has been said in connection with figure 12.

[0123] 34 and 35 show a variant of the implant 400 according to FIGS. 30 to 33. In FIG.

[0124] To avoid repetition, only the essential differences between implants 400a and 400b and implant 400 are described below, with explicit reference otherwise to what has been said above in relation to implant 400.

[0125] In the variant according to FIG. 34, the implant 400a is designed to be pre-fixed in a bore H extending radially around the outer periphery DA of the bone flap D (see FIG. 4).

[0126] The first part 401a therefore comprises an abutment surface 406a for insertion into said borehole H. In this respect reference can be made to a housing 415a, the cylindrical outer periphery of which forms the abutment surface 406a and so to speak the first part 401a. The housing 415a has unnumbered receiving clearances for receiving in one part the spring element 407a and the pressure element 408a and in another part the locking element 417a.

[0127] Otherwise, the locking element 417a is in the locked position of Fig. 34. The pressure element 408a is therefore fixed in its inner end position with respect to the transverse axis Y, against the spring force of the spring element 407a.

[0128] In the variant according to Fig. 35, the implant 400b does not have a mandrel part, but instead has a through hole 430b formed in the support part 420b for pre-fixing purposes.

[0129] For pre-fixation purposes, the implant 400b is screwed into the bone flap D.

[0130] The through holes 430b serve to receive the screws necessary for this purpose.

[0131] Figures 36 to 45 show a further embodiment of an implant 500 according to the invention, Figures 42 to 45 relating to a variant thereof.

[0132] 36-39, implant 500 has a longitudinal axis X, a transverse axis Y, a first portion 501, a second portion 502 and a mechanism 503. As shown in FIG.

[0133] Regarding the orientation of the longitudinal axis X and the transverse axis Y relative to the axial direction A and the radial direction R of the skull opening B, what has been said in connection with the previous embodiment applies.

[0134] The first portion 501 is designed to transmit forces to the bone flap D.

[0135] The second portion 502 is designed to transmit force to the skull K surrounding the skull opening B.

[0136] The mechanism 503 operatively connected to the two parts 501, 502 is essentially designed as in the previous embodiment to expand the lateral space between the two parts 501, 502. In this respect, the two parts 501, 502 can also in this embodiment be pressed by the mechanism 503 against the bone flap D on one side and against the skull K on the other side.

[0137] In this embodiment, mechanism 503 includes a first barrel element 508 (FIG. 37) and a second barrel element 509 (FIG. 38).

[0138] The first cylinder element 508 has a first longitudinal axis L1 and the second cylinder element 509 has a second longitudinal axis L2. The two longitudinal axes L1, L2 are oriented coaxially with respect to one another and along the transverse axis Y, specifically, likewise coaxially.

[0139] The first cylinder element 508 has a profiled first cylinder side 510 and a first surface 511. The first surface 511 forms and / or functions as the first portion 501.

[0140] The second barrel element 509 has a profiled second barrel side 512 and a second surface 513. The second surface 513 functions as and / or forms the second portion 502.

[0141] In the illustrated embodiment, the second surface 513 is the surface of the end face of the second barrel element 509. This second surface is designed to bear radially against the inner circumference KI of the skull K. The first surface 511 is the outer side of the first barrel element 508 and is designed to be inserted into a radially extending bore H at the outer circumference DA of the bone flap D (see FIG. 4).

[0142] In the illustrated embodiment, the first profiled cylinder side 510 is an inner side of the first cylinder element 508. In the illustrated embodiment, the second profiled cylinder side 512 is an outer side of the second cylinder element 509. Thus, in the illustrated embodiment, the first cylinder element 508 is a hollow cylinder and may also be referred to as a bushing, and the second cylinder element 509 may also be referred to as a bolt, pin, etc. In further embodiments, the reverse association is made instead, with the first cylinder element in the form of a bolt and the second cylinder element in the form of a bushing.

[0143] In the assembled, ready-to-use state (FIGS. 36 and 39), the first and second cylinder elements 508, 509 are axially plug-fitted to one another. More specifically, the second cylinder element 509 is axially inserted into the first cylinder element 508. At this point, the profiled first cylinder side surface 510 and the profiled second cylinder side surface 512 form a form-fit and / or pressure-fit connection V along the transverse axis Y (FIG. 39).

[0144] The above connection V can be established at various relative axial positions of the two cylinder elements 508, 509, ultimately resulting in varying the lateral spacing between the first portion 501 and the second portion 502.

[0145] In the illustrated embodiment, the connection V is a latching connection. Accordingly, the first barrel side 510 and the second barrel side 512 are profiled with latch features R1, R2, respectively, which may also be referred to as first latch feature R1 and second latch feature R2.

[0146] In the illustrated embodiment, the first latch shape R1 has a plurality of circumferential grooves 514 that are spaced apart from one another along the first longitudinal axis L1 and are each recessed in the radial direction of the first tube element 508 on the inner side of the first tube element 508 (FIG. 39).

[0147] In the embodiment shown, the second latch feature R2 of the second barrel element 509 has two latch projections 515 offset by 180° around the circumference of the second barrel element 509, the shape of which fits snugly into the circumferential groove 514. In this example, the latch projections 515 are located at the end of the second barrel element 509 remote from the second surface 513.

[0148] As shown in Fig. 39, the two latch features R1, R2 are configured in this embodiment such that the latch connection V can be latched on one side along the lateral axis Y. As a result, in the illustrated embodiment, the lateral space can only be expanded, not contracted. In other words, the first and second tube elements 508, 509 can be pulled out, but not pushed in.

[0149] FIG. 41 shows an intraoperative situation for the fixation of a bone flap D with the implant 500. For the purpose of pre-fixation, the implant 500 is first inserted into the bore H with the first barrel element 508 at the front. In the embodiment shown, the first barrel element 508 has an unnumbered profile on its outer side with a number of projections 516 spaced apart from one another along the first longitudinal axis L1 and each extending circumferentially. These projections serve to improve the pre-fixation and form a kind of a ratchet. After the pre-fixation is completed, the bone flap D together with the implant 500 is inserted into the opening B. By latching the latch connection V on one side, the surface 513 of the end face of the second part 502, in this case the second barrel element 509, bears against the inner circumference KI of the skull K.

[0150] The tensile force along the transverse axis Y required for this is applied in this embodiment via a pulling eye 517, which is in this embodiment a transverse bore arranged in the region of the end face 513. To apply a tensile force to the second tube element 509, for example a tool suitable for this can be introduced into the pulling eye 517.

[0151] To facilitate the latching on the latch connection V, in the illustrated embodiment the second tube element 509 has a longitudinal slit 518, which extends at one end in the axial direction of the second tube element 509 and allows a resilient radial movement of the latch projection 515. In this respect, a slight modification is shown in FIG. 40, in which a second tube element 509e is provided with a modified longitudinal slit 518e. The longitudinal slit 518e has a widened portion 519e at its closed end. The widened portion 519e is arranged in the region of the pulling eye 517e and runs parallel to it in a manner similar to the through hole. The widened portion 519e assists in a proper resilient movement of the latch projection.

[0152] With reference to FIG. 41 it is also shown that the bone flap D is fixed by a number of implants 500, 500', 500''. Such fixation by a number of, in particular structurally identical, implants is advantageous but not essential. In principle it is also conceivable to fix the bone flap D by only a single implant.

[0153] 42 to 45 show variants of the implant 500. The functions and configurations of the variants shown are substantially identical to the implant 500. To avoid repetition, only the essential differences are described below. Functionally and structurally identical parts and / or portions are not described separately. Instead, explicit reference is made to what has been said in connection with the implant 500.

[0154] In the variant according to FIG. 42, the implant 500a is provided with a screw connection Va instead of the latch connection V. That is to say, the first barrel element 508a and the second barrel element 509a are screwed to one another for a screw-in movement along the transverse axis Y. For this purpose, the first barrel element 508a has a first thread profile R1a. The second barrel element 509a has a complementary second thread profile R2a. In this case, the first thread profile R1a is an internal thread. The second thread profile R2a is an external thread.

[0155] The variant according to Fig. 43 provides that the implant 500b is screwed into the bore H. For this purpose, the outer flank 511b has an external thread 530b, not shown in detail in the drawings. The external thread 530b is preferably a self-tapping and / or self-boring thread.

[0156] In the variant according to Fig. 44, the implant 500c has a modified latch connection Vc. The latch connection Vc is formed between a radial collar 514c arranged on the end face of the second barrel element 509c and a spring element 515c arranged on the inner lateral surface of the first barrel element 508c. The spring element 515c is elastically flexible outwardly in the radial direction of the barrel elements 508c, 509c.

[0157] In the variant according to FIG. 45, in a simplified manner, the first and second tube elements 508d, 509d are assigned a bush shape on the one hand and a bolt shape on the other hand in reverse. The implant 500d thus has a bolt-shaped first tube element 508d and a bush-shaped second tube element 509d. The first tube element 508d is designed to be inserted into the bore H of the bone flap D and has a number of anchor elements 516d on its outer side 511d. The second tube element 509d is inserted at one end into the first tube element 508d and latched to it. For this purpose, the outer side 511d at least partially has a first latching profile R1d. The unlabeled inner side of the second tube element 509d has a complementary second latching profile R2d. The end face 513d of the second tube element 509d is provided with a pawl not labeled. This improves the contact with the inner circumference KI of the skull.

[0158] Figure 46 shows a further intraoperative situation in which a bone flap D is fixed by means of a first implant 500, a structurally identical further implant 500' and a pin 600. The pin 600 is shown in detail in Figure 47 and is provided on its outer lateral side with a first claw Z1 and a second claw Z2. The first claw Z1 serves to improve the fixation of the pin in the bore H'' (see Figure 46) of the bone flap D. The second claw Z2 serves to improve the anchorage of the pin 600 in an unnumbered bore formed in the surrounding skull K.

[0159] 48 shows an alternatively configured pin 600a, which has sharp end faces on both its axial sides. The sharp end faces allow the pin 600a to be pressed into both the outer periphery DA of the bone flap D and the inner periphery KI of the skull. This makes it possible, in contrast to the pin 600, to omit drilling a bore in the skull K and / or in the bone flap D.

Claims

1. An implant (100, 200, 300, 400, 500) for fixing a cranial bone flap (D) in a cranial opening (B), comprising: A longitudinal axis (X) extending along the axial direction (A) of the skull opening (B); A transverse axis (Y) extending along a radial direction (R) of the skull opening (B); a first part (101, 201, 301, 401, 501) designed to transmit a force to said bone flap (D); a second part (102, 202, 302, 402, 502) designed to transmit forces to a skull (K) surrounding said skull opening (B), said first part (101, 201, 301, 401, 501) and / or said second part (102, 202, 302, 402, 502) are designed to be placed in an annular gap (S) formed between an outer periphery (DA) of said bone flap (D) and an inner periphery (KI) of said skull (K); a mechanism (103, 203, 303, 403, 503) operatively connected to said first portion (101, 201, 301, 401, 501) and said second portion (102, 202, 302, 402, 502), said mechanism (103, 203, 303, 403, 503) interposing between said first portion (101, 201, 301, 401, 501) and said second portion (102, 202, 302, 402, said mechanism being capable of at least expanding a lateral space (Q) projected on said lateral axis (Y) between said first portion (101, 201, 301, 401, 501) and said second portion (102, 202, 302, 402, 502) so as to press said first portion (101, 201, 301, 401, 501) inwardly in said radial direction (R) against said bone flap (D) and to press said second portion (102, 202, 302, 402, 502) inwardly in said radial direction (R) against said skull (K); An implant (100, 200, 300, 400, 500) comprising:

2. 2. The implant (100, 200, 400, 500) according to claim 1, characterized in that the mechanism (103, 203, 403, 503) is designed for a translational displacement of the first part (101, 201, 401, 501) and / or the second part (102, 202, 402, 502) along the transverse axis (Y).

3. 3. The implant (300) according to claim 1 or 2, characterized in that the mechanism (303) is designed for rotational displacement of the first part (301) and / or the second part (302) about the longitudinal axis (X).

4. 4. An implant (100, 200, 300, 400, 500) according to any one of claims 1 to 3, characterized in that the first part (101, 201, 301, 401, 501) has a first contact surface designed to bear radially against the outer periphery (DA) of the bone flap (D) and / or the second part (102, 202, 302, 402, 502) has a second contact surface designed to bear radially against the inner periphery (KI) of the skull.

5. The first portion (101, 501) has a joining surface (106, 511); The implant (100, 500) according to any one of claims 1 to 4, characterized in that the joint surface (106, 511) is designed to be inserted into a bore (H) extending radially around the outer periphery (DA) of the bone flap (D).

6. There is a support (220, 320, 420), 6. The implant (200, 300, 400) according to any one of claims 1 to 5, characterized in that the support part (220, 320, 420) has a lower surface (221, 321, 421) arranged above the first part (201, 301, 401) and the second part (202, 302, 402) along the longitudinal axis (X) and designed to support the outer surface (KF) of the skull (K) and the outer surface (DF) of the bone flap (D).

7. 7. An implant (200) according to claim 6, characterized in that the support (220) is connected to the remainder of the implant (200) by a removable joint connection means, in particular a bayonet fastening.

8. There is at least one mandrel portion (223, 323, 423); The implant (200, 300, 400) according to any one of claims 1 to 7, characterized in that the mandrel portion (223, 323, 423) extends along the transverse axis (Y) and at one end has a mandrel tip (224, 324, 424) protruding beyond the first portion (201, 301, 401) and designed to radially penetrate the outer periphery (DA) of the bone flap (D).

9. The mechanism (203) comprises at least one clamping element (208) and a cone element (207); the clamping element (208) is mounted for movement along the transverse axis (Y) and has an inner conical surface (210) and an end surface (211) forming the first portion (201) or the second portion (202); said conical element (207) is mounted for movement along said longitudinal axis (X) and has an outer conical surface (214) which interacts with said inner conical surface (210); 9. An implant (200) according to any one of the preceding claims, characterized in that the clamping element (208) is displaceable along the transverse axis (Y) by a movement of the conical element (207).

10. The mechanism (203) has a further clamping element (209), 10. Implant (200) according to claim 9, characterized in that the further clamping element (209) is displaceable in the opposite direction along the transverse axis (Y) by a movement of the conical element (207).

11. The conical element (207) has a screw thread (216), 11. An implant (200) according to claim 9 or 10, characterized in that said thread (216) is adapted to be engaged with a complementary mating thread (217) for threaded movement along said longitudinal axis (X).

12. the mechanism (303) has a rotation axis (G) oriented along the longitudinal axis (X) and an eccentric element (308) movably mounted about the rotation axis (G) and having a contour (311) eccentric with respect to the rotation axis (G); Different portions of said contour (311) form said first portion (301) and said second portion (302); The implant (300) according to any one of claims 1 to 8, characterized in that the rotation of the eccentric element (308) causes the contour (311) to be clamped between the outer periphery (DA) of the bone flap (D) and the inner periphery (KI) of the skull (K).

13. a shaft element (307) having said eccentric element (308) disposed at one end thereof and a tool engagement element (319) disposed at its other end; 13. The implant (300) according to claim 12, characterized in that the tool engagement element (319) is designed to apply a torque directed around the axis of rotation (G).

14. The implant (300) according to claim 13, characterized in that the tool engagement element (319) forms an upper end of the implant (300) with respect to the longitudinal axis (X) and is connected to the shaft element (307) via a predetermined break (317).

15. the eccentric element (308) has at least a first blade portion (309) forming the first portion (301) and a second blade portion (310) offset with respect to the axis of rotation (G) and forming the second portion (302); The implant (300) according to any one of claims 12 to 14, characterized in that the blade portions (309, 310) each have a longitudinal extent, protrude radially from the axis of rotation (G) and have cutting edges (312, 313) facing oppositely to each other.

16. The mechanism (403) comprises a pressure element (408) and a spring element (407), the pressure element (408) extends along the transverse axis (Y) between a first end surface (409) forming the first part (401) or the second part (402) and a second end surface (410) and is mounted so as to be movable along the transverse axis (Y); The spring element (407) is at least indirectly supported by the second end surface (410); 9. An implant (400) according to any one of the preceding claims, characterized in that the pressure element (408) is spring-biased along the transverse axis (Y) by the spring element (407).

17. A locking element (417) is present; The implant (400) according to claim 16, characterized in that the locking element (417) is displaceable relative to the pressure element (408) between a locked position in which the locking element (417) fixes the pressure element (408) with respect to the transverse axis (Y) against the spring force of the spring element (407), and a released position in which the pressure element (408) is free to move along the transverse axis (Y).

18. The mechanism (503) comprises a first cylindrical element (508) and a second cylindrical element (509) whose longitudinal axes (L1, L2) are coaxial and extend parallel to the transverse axis (Y); The first cylinder element (508) has a profiled first cylinder side (510) and a first surface (511) forming the first portion (501); the second cylinder element (509) has a second cylinder side (512) with a complementary profile and a second surface (513) forming the second portion (502); The implant (500) according to any one of claims 1 to 8, characterized in that the first cylinder side surface (510) and the second cylinder side surface (512) are connectable to each other to form a connection (V) that is form-fit and / or pressure-fit along the transverse axis (Y) at different axial relative positions of the cylinder elements (508, 509).

19. the second surface (513) is a surface of the end face of the second tube element (509) and is designed to abut and support the inner circumference (KI) of the skull (K) in a radial direction; The implant (500) according to claim 18, characterized in that the first surface (511) is an outer side surface of the first cylindrical element (508) and is designed to be inserted into a radially extending bore (H) at the outer periphery (DA) of the bone flap (D).

20. 20. An implant (500) according to claim 18 or 19, characterized in that said first cylindrical side surface (510) is an inner side surface and said second cylindrical side surface (512) is an outer side surface.

21. 21. An implant (500) according to any one of claims 18 to 20, characterized in that the first cylindrical side surface (510) and the second cylindrical side surface (512) each have a profile with a latch shape (R1, R2) and are latched to each other along the transverse axis (Y) so that they can be latched one to the other on one side.

22. The implant (500) of any one of claims 18 to 20, characterized in that the first cylindrical side surface (510) and the second cylindrical side surface (512) each have a thread-shaped (R1a, R2a) profile and are threadedly engaged with each other for threaded movement along the transverse axis (Y).

23. An implant system comprising at least two implants (100, 200, 300, 400, 500) according to any one of claims 1 to 22.

Images