DE19816832C1 - Surgical vertebral implant - Google Patents

Abstract

The surgical vertebral implant has a frame (3,4) with a support (2) body which is rotatably mounted and has a rib (14) eccentric to its rotary axis. The rib can be retracted for insertion of the implant and then extended for anchoring it.

Description

The invention relates to an in the intervertebral space insertable vertebral body fusion implant with attachment surfaces for neighboring vertebral bodies.

Such implants are for example in the EP 260 044 B1, in WO 92/14423, in WO 97/0054 or described in DE 43 23 956 C1. All this implan acts is common that after the removal of the business inserted intervertebral disc in the intervertebral space can be and then by removing the investment separate the neighboring vertebrae press on. The contact areas are essentially lichen flat on the vertebral body surfaces, each Be movement of the contact surfaces of the implant also to shift the vertebrae towards each other and to widen the intervertebral space.

In WO 97/15246 an intervertebral implant is wrote that from a cage and a rotating body per exists. The rotating body is with a screw threaded and serves the entire implan did by twisting the cage in the twos screw in vertebrae. The contact areas have with this implant always a constant distance  from each other, so that the intervertebral space widens must be in order to insert the implant.

It is an object of the invention, a generic We belbody fusion implant to create that in easier Insertable in the intervertebral space and there is definable.

This task is done with a vertebral fusion implant did the type described above according to the invention solved by that on a frame of the vertebral body  sionsimplantates at least one bearing body rotatable ge is at least one who is eccentric to his Supporting axis extending support rib, and that the Support rib in an inserted position of the bearing body minimally outwards from the vertebral body fusion implant protrudes and in a support position from the maximum this emerges.

With such a configuration, it is possible Vertebral fusion implant in one position of the or insert the bearing body into the intervertebral space ben, in which support ribs are minimal at best protrude from the implant so that the intervertebral vertebra not particularly widened when inserted or would even have to be expanded. After the one the support ribs are pushed through Rotation of the corresponding bearing body from the Im extended plantat, whereby it stands out through its training as a rib in the material of the neighboring vertebrae can bury bodies. This burial is particularly promoted in particular that the narrow support ribs when rotating the bearing body not only in the connector direction of movement of the neighboring vertebral body the, but also in the circumferential direction of the ribs, so that through this movement they are steadily into the bone dimension material of the vertebral body can dig.

As soon as the bearing bodies are in the support position, the ribs are completely in the adjacent vertebrae body penetrated, so that on the one hand a support radio is given in the longitudinal direction of the spine, others on the one hand, the implant is transverse against displacement optimally secured to the longitudinal direction of the spine.  

Basically, it would be sufficient if a bearing body only carries such a support rib, but it is a preferred embodiment provided that the Bearing bodies next to each other at a distance from each other Support ribs that are eccentric in the same way run to the axis of rotation of the bearing body. This much Total number of support ribs acts as an investment or Support surface, so that not only the Fixing is secured in the axial direction, but a support function is also assumed, this Support surface by extending the support ribs in ih rer effective position relative to the implant is.

In a preferred embodiment can be provided be that each support rib through the outer edge of a Washer is formed, which rotatably with the bearing body connected is.

In particular, this disc can be circular and be connected eccentrically to the bearing body.

While usually all the support ribs of a bearing block pers equal in their dimensioning and arrangement are formed, with a modified version tion form of a bearing body with several support ribs be provided that the maximum distance of the support rip pen from the axis of rotation of the bearing body over the length of the bearing body is different, for example the maximum distance of the support ribs from the axis of rotation from the center of the bearing body towards its ends to take. This makes it possible to trace the contour through  the support ribs formed support surface to the anatomi adapt to the circumstances, for example to the geometric shape of the vertebral end surface.

The support ribs can in principle by discs same thickness are formed, with a preferred However, embodiment is provided that the support ribs become narrower towards the outside.

The support ribs can end in a blunt edge, so that a maximum carrying function is guaranteed here is. In this case it is advantageous if the be neighboring vertebral bodies for the inclusion of such Support rib is prepared, for example by a Milling with an eccentric cutter.

But it can also in another embodiment be provided that the support ribs have a sharp edge train, this will dig the ribs into the Bone material of the vertebral body encourages the support ribs cut themselves even when twisting the Bearing body in the bone material, so that given if necessary, prepare the end of the vertebral body can be omitted.

In a particularly simple embodiment, a Implant only a single bearing body, so that the implant on one side when inserted Side supported by the frame on a vertebral body on the opposite side the extended support ribs.  

In a modified embodiment, however also be provided that on the frame diametrically ge opposite two bearing bodies with at least one each a support rib are mounted, these support ribs can then from diametrically opposite sides be driven.

An embodiment in which it is provided that on the frame in the circumferential direction distributes three bearing bodies with at least one each Support rib are stored. With such a configuration tion, the implant becomes additional when inserted secured against lateral tilting because then the support ribs of two bearing bodies on one Support the vertebrae, the support ribs of the third La body on the adjacent vertebral body.

In the case of an implant with several bearing bodies, each the bearing body can be rotated by itself, it can be a preferred embodiment but also a Kopp ment of the bearing body through which the La body can be rotated together. This could be done for example by a gear mechanism on the implant realize.

A particularly compact design of an implant with at least two bearing bodies results if the Support ribs of a bearing body in the inserted position the bearing body in spaces between the support rib Immerse the pen of the other bearing bodies. By in Support ribs of the bearing bodies offset in the axial direction the axes of rotation of the bearing body can be relatively tight are brought closer together so that an implant with  low height can be produced, which without problems in the intervertebral space can be introduced.

The bearing body can in particular be a shaft.

In a preferred embodiment, that the frame by two independent La is formed, each of which bearing openings conditions for the rotatable mounting of at least one storage unit pers has, and that the bearing body on their two Each ends in one of the bearing elements around its length axis rotatable and axially immovable. The bearing elements can be relatively small have axial extension, for example they can also be disc-shaped. The whole area between the bearing elements thus remains exclusively the bearing bodies with the support rip worn by them pen reserved, in this area there are no disturbing Pre-connecting elements between the bearing elements see.

In a preferred embodiment, that on one of the bearing elements, the bearing openings for The outer edge of the bearing elements are open in such a way that the bearing body stored in them radially outwards is movable. On the one hand, this means manufacturing simplified, on the other hand results from a ge slight radial displacement of the bearing body Possibility to insert locking elements between the bearing body push on.

It is advantageous if the bearing elements have a through have refraction that gives access to the space between  releases the bearing elements. Through this through If necessary, refractions can result in bone material change in the growth.

In a particularly preferred embodiment provided that in the space through the breakthrough a core can be inserted if the or the bearing bodies are in the support position, if so between the adjacent bearing bodies by the maxi times extended support ribs space is created.

It can be provided that the core on the support rib the bearing body in the support position so that a turning back of the bearing body is prevented in the insertion position. The core bil det a stop for the two bearing bodies and fixes this in the extended support position.

The core can in particular over a part Connect the circumferential area of the support ribs to them.

It is favorable if the core is in the opening is held rotatable. This is for example by a corresponding non-circular shape of the opening and of the core in this area.

It is also advantageous if means are on the core for axially fixing the core relative to the bearing bodies and the bearing elements are provided so that the core does not accidentally move in the axial direction can move.  

For example, these means for axial fixation Projection be projections that are in a recess snap.

It is particularly advantageous if the funds are on the core and arranged on the bearing bodies in this way are that they only have the core relative to the bearing bodies set when the bearing body in the support position stand.

This is especially true when the funds are the stock body against the core also against rotation of the Secure the bearing body. You then get a mutual one Locking the core and the bearing body against both an axial displacement as well as against rotation the bearing body, and this lock is only there effective when the bearing body is in the maximum standing support position.

The core can have a type limiting the insertion depth have impact, for example in the form of a side projecting flange section.

In a preferred embodiment, that the core in its middle, between the supports rib inserted section at least one through has refraction, in particular this breakthrough chung in the longitudinal direction of the core over the be an elongated hole for most of its length. This opening or these openings serve the absorption of bone material and promote the through growth of the implant, the core can be of the type  Drawer filled with bone material in between be inserted between the bearing body.

It is advantageous if the core is inserted at Nem arranged outside of the bearing element since Liche depression, for example in the form of a Circumferential groove. This deepening is used to start one Tool, with the help of which the core from the implant can be pulled out.

Furthermore, it can be provided that the bearing body frontal contact surfaces for a ver the bearing body have rotating tool, for example Contact surfaces by a concentrically arranged, un round insertion opening can be formed for a tool, about a hexagon opening.

The following description of preferred embodiment forms of the invention is used in connection with the Drawing of the detailed explanation. Show it:

Fig. 1: a perspective view of a We belkörperfusionsimplantates with the La gerkörpern in insertion position without inserted core;

FIG. 2: a longitudinal sectional view of the implant of FIG. 1 with the bearing bodies in a push position;

Fig. 3 is a view of the implant of Figure 2 in the direction of arrow A;.

Fig. 4 is a sectional view taken along line 4-4 in Fig. 2;

Fig. 5: A perspective view of the implant of Figure 1 with the Lagerkör pern in support position and with a partially inserted core.

Fig. 6 is a perspective view of the core;

. Fig. 7 is a view similar to Figure 2 with the La gerkörpern in the support position and with inserted core;

Fig. 8: an enlarged detail view of the loading area C in Figure 7 in an embodiment with sharp-edged ribs;

Fig. 9 is a sectional view taken along line 9-9 in Fig. 7;

Fig. 10 is a view of the implant of Figure 7 in the direction of arrow B;.

Fig. 11 is a view similar to Figure 7, in one embodiment with the length of the bearing body differently formed support ribs;.

FIG. 12: a front view of the implant of FIG. 11 in the inserted state;

FIG. 13: a view similar to FIG. 11 for an implant with only one bearing body with supporting ribs of the same type;

FIG. 14: a front view of the implant of FIG. 13 in the inserted state;

Fig. 15: a side view of a modified embodiment of an implant with three gerkörpern provided with support ribs and La

FIG. 16: a front view of the implant of FIG. 15 in the inserted state.

The vertebral body shown in Figs. 1 to 10 fusion implant 1 has two mutually parallel running ver bearing shafts 2, the elements between two Lagerele 3 are mounted to rotate about its longitudinal axis 4.

The bearing element 3 is disc-shaped and has two eccentrically and with respect to a radial plane of the bearing element 4 symmetrically arranged bearing openings 5 , which are open on their sides facing away from one another up to the outer edge 6 of the bearing element 3 , that is, each of the bearing openings 5 goes from the other bearing openings 5 directed radia ler slot 7 from ( Fig. 3).

In the other bearing element 4 , which is also disc-shaped, two bearing openings 8 are provided eccentrically and symmetrically to a radial plane of the disc, but are closed.

The bearing shafts 2 pass through these bearing openings 8 and are extended at their end 9 protruding from the bearing element 4 , so that the bearing element 4 is captively fixed on the two bearing shafts 2 .

At their opposite end 10 , both bearing shafts 2 protrude from the bearing element 3 and carry there a head-shaped thickening 11 , in which a hexagon socket 12 is worked concentrically to the axis of rotation of the bearing shafts 2 , which is open towards the end 10 . In the sen hexagon 12 a tool can be used who, so that by means of this tool, the bearing shafts 2 in the two bearing elements 3 , 4 can be rotated independently of one another.

Both bearing shafts 2 carry a plurality of mutually spaced, transverse to the axis of rotation of the bearing shafts 2 extending circular discs 13 , all discs 13 of a bearing shaft 2 in the same way relative to the axis of rotation of this bearing shaft 2 are arranged eccentrically. The outer edges 14 of these disks 13 form support ribs. The disks 13 have a small axial extension relative to the extension of the bearing shaft 2 , so that relatively narrow outer edges 14 result. These can, for example, be rectangular in cross section ( FIG. 7), but in the case of modified embodiments, the thickness of the disk can also decrease towards the outside, so that sharp outer edges 14 are formed ( FIG. 8).

The discs 13 of the two bearing shafts 2 are offset from each other in axia ler direction that the ticket ben of a support shaft 2 in the spaces 15 of the discs 13 of the other bearing shaft 2 can plunge.

In a first angular position of the two bearing shafts 2 , in which the disks 13 are directed with their most protruding region in the radial direction in the direction of the respective other bearing shaft 2 , the bearing shafts 2 are in a so-called an insert position ( FIG. 1 to 4), in this position the vertebral body fusion implant 1 has a minimal overall height. The disks 13 of the two bearing shafts 2 dip into the intermediate spaces 15 and can reach as close as possible to the other bearing shaft 2 .

If the bearing shafts 2 are rotated by 180 ° in each case, ra discs 13 with their eccentric outer edges 14 protrude maximally in the radial direction from the vertebral fusion implant 1 , so that a maximum overall height is achieved ( FIGS. 7 to 10). The side edges 14 arranged side by side together each form a contact surface for an adjacent vertebral body, this contact surface consists of the support ribs running parallel to one another.

In both bearing elements 3 , 4 an opening 16 and 17 is arranged between the respective gene bearing openings 5 and 8 , these openings have the shape of a dumbbell in the Darge presented embodiment. When the bearing shafts 2 are in their supporting position, a core 18 can be inserted between the two bearing shafts 2 through the opening 16 of the bearing element 3 . This core 18 has a cross section which corresponds to that of the openings 16 and 17 , so that the core 18 is held in the inserted state in a rotationally fixed manner in the two openings 16 and 17 . The insertion depth is limited by laterally from the core 18 from standing flange sections 19 , which come to rest on the bearing element 3 , and the core 18 is fixed in the inserted position in the axial direction by radial projections 20 on the core 18 in ra diale recesses 21st immerse in the head-shaped thickening 11 of the two bearing shafts 12 ( FIG. 7). Before the jumps 20 are formed, for example, by a pin 22 which sets a transverse bore 23 in the core 18 , is axially fixed in this and protrudes slightly over the circumference of the core 18 . The recesses 21 in the thickening 11 are formed by lateral bores 24 which are arranged in the circumferential direction so that the projections 20 then engage in the recesses 21 when the bearing shafts 2 are in the fully extended support position and when the core 18th is fully inserted.

Through the engagement of the projections 20 in the recesses 21 not only the core 18 is fixed in the axial direction, but also the two bearing shafts 2 who secures the ge against rotation out of the support position.

The insertion of the core 18 and the snapping of the projections 20 into the recesses 21 is further facilitated by the fact that the bearing shafts 2 in the bearing element 3 through the laterally open bearing openings 5 can dodge slightly in the radial direction.

The core 18 lies in the inserted state with its upper side 25 and its lower side 26 against the outer edges 14 of the disks 13 and thereby also prevents the two bearing shafts 2 from rotating against one another. The tops 25 and 26 are formed bogenför shaped and adapted in radius to the radius of the outer edge 14 .

In the area between the two bearing elements 3 and 4 , the core 18 has a continuous, elongated opening 27 , which forms a connection between the ben 13 at the bearing shafts 2 and the cry carried by them. This opening 27 is large and thus forms a receiving chamber for bone material.

A peripheral groove 32 adjoins the flange sections 19 towards the end of the core 18 , into which a tool can be inserted, with the aid of which the core 18 can be pulled out of the vertebral body fusion implant 1 .

The described vertebral body fusion implant 1 preferably consists of a body-compatible metal, for example made of titanium or a titanium-aluminum alloy.

This implant is inserted into an intervertebral space 28 from which the intervertebral disc has previously been removed. This removal can take place, for example, with the method of percutaneous intervertebral disc surgery (H. Leu and A. Schreiber, Discoskopie in Arthrosko pie, 1993/6 :, pages 3-9). In this method of operation, the intervertebral disc is removed through a dorso-laterally inserted working sleeve, and this working sleeve can also be used to insert the described implant. This is possible because the implant has very small external dimensions when the bearing bodies are in the inserted position, for example an outer diameter of less than 10 mm, so that the implant can be advanced in the longitudinal direction through the working sleeve into the intervertebral space, which also does not apply to the rest or only needs to be expanded slightly.

After insertion of the implant into the intermediate space 28 , the two bearing shafts 2 are rotated by a tool which is also guided through such a working sleeve and which is inserted into the hexagon socket 12 . During this rotation, the outer ribs 14 of the disks 13 forming the supporting ribs come to rest on the vertebral space 28 adjacent to the vertebral bodies 29 , 30 and dig into wider vertebral bodies 29 and 30 , where the digging occurs once through the formation of the off vertical edges 14 is supported as a narrow rib or even a sharp edge, but also by moving this outer edge 14 in the circumferential direction. From the cut edges 14 cut into the bone material rial without the vertebral bodies 29 and 30 being significantly displaced in their distance.

As soon as the bearing shafts 2 are in their supporting position, that is to say rotated by 180 ° with respect to the insertion position, the core 18 is likewise inserted through the working sleeve into the implant until the projections 20 snap into the recesses 21 . The core 18 is filled with bone material before insertion in the area of its opening 27 , so that the core 18 is inserted like a drawer filled with bone material into the space between the bearing shafts 2 .

It is entirely possible to use two such implants 1 in an intervertebral space 28 , these implants then being arranged at an angle to one another, in particular when introduced through a dorso-lateral working sleeve in the intervertebral space.

Basically, it is not necessary to prepare the vertebral bodies 29 and 30 especially for the inclusion of the described implant. But it can be seen before that the vertebral bodies 29 and 30 in the bearing area of the outer edges 14 are slightly processed before the implantation is inserted, for example with the aid of a milling head, as described in the literature reference H. Leu and A. Schreiber in Fig. 4 is shown. It is an eccentrically abrasive milling cutter, with which in the mutually facing end faces of the vertebral bodies 29 and 30 before the implant 1 is milled in cross-section bogenformi channels, the diameter of which is preferably less than the path of motion 31 of the White test portions of the outer edge 14 of the disks 13 ( FIG. 10) removed from the axis of rotation of the bearing shaft 2 , so that it is ensured that when the implant was inserted the outer edges 14 continued to penetrate into the material of the vertebral bodies 29 and 30 .

In the exemplary embodiment in FIGS. 11 and 12, an implant similar to that in FIGS. 1 to 10 is shown, parts which correspond to one another therefore have the same reference symbols. While in the Ausführungsbei of Figure 1 play. To 10, supported on a bearing body disks 13 of the same design, so that the outer edges 14 of the discs 13 together define a circular cylindrical outer surface, the diameter of the discs 13 in the embodiment of Figs. 11 and 12 with each bearing shaft 2 over its length, in this case in the form that the diameter of the disks 13 is largest in the center of the bearing body and decreases towards both ends. This results in an envelope surface spanned by the outer edges 14 , which is further away from the implant in the middle of the implant than at its ends. This makes it possible to adapt this envelope to the anatomical conditions, for example to the geometric shape of the vertebral end surfaces.

In the embodiment of FIGS. 13 and 14, a similar overall structure of the implant is again selected as in the embodiment of FIGS. 1 to 10, corresponding parts therefore have the same reference numerals here as well.

In contrast to the exemplary embodiment of FIGS. 1 to 10, only a single bearing shaft 2 with corresponding disks 13 is provided in this implant, so that the outer edges 14 can only be extended out of the implant on one side. In order to enable a flat support of the implant on the side opposite the bearing shaft 2 , the bearing elements 3 and 4 are flattened there ( FIG. 14).

In contrast to this, the implant of FIGS. 15 and 16, which is also identified by the same reference numerals in the case of a substantially similar structure, has three bearing shafts 2 with corresponding disks 13 in the implant, each of which is offset in the circumferential direction by 120 ° relative to the Bearing elements 3 and 4 are stored. It is therefore possible, when the disks 13 are extended on a vertebral body, to support the implant via two contact areas, so that twisting or tilting of the implant in the intervertebral space is avoided with certainty. Of course, will be adapted in such an embodiment the gerelemente between the La 3 and 4 inserted core 18 in its cross-sectional shape thereto, that in this Implan did three bearing shafts 2 stored are, for example, this core may th a star-shaped cross-section sustainer as shown in Fig. 16 is shown.

Claims (32)

1. In the intervertebral space insertable vertebral body perfusion implant with contact surfaces for neighboring vertebral bodies, characterized in that on a frame ( 3 , 4 ) of the vertebral body fusion implant ( 1 ) at least one bearing body ( 2 ) is rotatably mounted, which has at least one eccentric to its axis of rotation extending supporting rib (14), and that the supporting rib (14) in a one slide position of the bearing body (2) protrudes minimally outwardly from the interbody fusion implant (1) and a maximum emerges in a supporting position therefrom. 2. Implant according to claim 1, characterized in that the bearing body ( 2 ) carries a plurality of supporting ribs ( 14 ) next to one another at a distance from one another, which extend eccentrically to the axis of rotation of the bearing body ( 2 ) in the same way. 3. Implant according to claim 1 or 2, characterized in that each support rib ( 14 ) is formed by the lower edge of a disc ( 13 ) which is rotatably connected to the bearing body ( 2 ). 4. Implant according to claim 3, characterized in that the disc ( 13 ) is circular and is eccentrically connected to the bearing body ( 2 ). 5. Implant according to one of claims 3 or 4, characterized in that in a bearing body ( 2 ) with a plurality of support ribs ( 14 ) the maximum was from the support ribs ( 14 ) from the axis of rotation of the bearing body ( 2 ) over the length of the bearing body ( 2 ) is different. 6. Implant according to claim 5, characterized in that the maximum distance of the support ribs ( 14 ) from the axis of rotation of the bearing body ( 2 ) from the center of the bearing body ( 2 ) decreases towards its ends. 7. Implant according to one of the preceding claims, characterized in that the supporting ribs ( 14 ) become narrower towards the outside. 8. Implant according to one of the preceding claims, characterized in that the supporting ribs ( 14 ) end in a blunt edge. 9. Implant according to one of claims 1 to 7, characterized in that the support ribs ( 14 ) form egg ne sharp edge. 10. Implant according to one of the preceding claims, characterized in that on the frame ( 3 , 4 ) diametrically opposite two bearing bodies ( 2 ) with at least one support rib ( 14 ) are gela gert. 11. Implant according to one of claims 1 to 9, characterized in that three bearing bodies ( 2 ), each with at least one support rib ( 14 ), are mounted on the frame ( 3 , 4 ) in the circumferential direction. 12. Implant according to one of the preceding claims, characterized in that in the case of an implant with a plurality of bearing bodies ( 2 ) a coupling of the bearing body ( 2 ) is provided, through which the bearing body ( 2 ) can be rotated together. 13. Implant according to one of the preceding claims, characterized in that in the case of an implant with at least two bearing bodies ( 2 ), the support ribs ( 14 ) of a bearing body ( 2 ) in the insertion position of the bearing body ( 2 ) in spaces ( 15 ) between the Immerse the support ribs ( 14 ) of the other bearing body ( 2 ). 14. Implant according to one of the preceding claims, characterized in that the bearing body ( 2 ) is a shaft. 15. Implant according to one of the preceding claims, characterized in that the frame is formed by two mutually independent bearing elements ( 3 , 4 ), each of which has bearing openings ( 5 or 8 ) for rotatably supporting at least one bearing body ( 2 ), and that the bearing body ( 2 ) at its two ends ( 9 , 10 ) in each of the bearing elements ( 3 and 4 ) are rotatably mounted about their longitudinal axis and axially immovable. 16. Implant according to claim 15, characterized in that on one of the bearing elements ( 3 ) the La geröffnungen ( 5 ) to the outer edge ( 6 ) of the Lagerele element ( 3 ) are open in such a way that the bearing body ( 2 ) stored in them is radially slidable ver. 17. Implant according to one of claims 15 or 16, characterized in that the bearing elements ( 3 , 4 ) have an opening ( 16 or 17 ), the egg nen access in the space between the bearing elements ( 3 , 4 ) releases. 18. Implant according to claim 17, characterized in that a core ( 18 ) can be inserted into the space through the opening ( 16 ) through when the bearing body (s) ( 2 ) are in the supporting position. 19. Implant according to claim 11, characterized in that the core ( 18 ) on the supporting ribs ( 14 ) of the bearing body ( 2 ) standing in the supporting position rests in such a way that a turning back of the bearing body ( 2 ) is prevented into the insertion position. 20. Implant according to claim 19, characterized in that the core ( 18 ) over a partial circumferential region of the support ribs ( 14 ) closes at these. 21. Implant according to one of claims 18 to 20, characterized in that the core ( 18 ) in the opening ( 16 ) is held non-rotatably. 22. Implant according to one of claims 18 to 21, characterized in that means ( 20 ) for axially fixing the core ( 18 ) relative to the bearing bodies ( 2 ) and the bearing elements ( 3 , 4 ) are provided on the core ( 18 ) are. 23. An implant according to claim 22, characterized in that these means for axially fixing Before cracks ( 20 ) which snap into a recess ( 21 ). 24. Implant according to one of claims 22 or 23, characterized in that the means ( 20 , 21 ) on the core ( 18 ) and on the bearing bodies ( 2 ) are arranged such that they relative to the core ( 18 ) Only fix the bearing bodies ( 2 ) when the bearing bodies ( 2 ) are in the support position. 25. Implant according to claim 24, characterized in that the means ( 20 , 21 ) secure the bearing body ( 2 ) relative to the core ( 18 ) against rotation of the bearing body ( 2 ). 26. Implant according to one of claims 18 to 25, characterized in that the core ( 18 ) has a stop limiting the insertion depth ( 19 ). 27. Implant according to one of claims 18 to 26, characterized in that the core ( 18 ) in its middle, between the support ribs ( 14 ) inserted section has at least one opening ( 27 ). 28. Implant according to claim 27, characterized in that the opening ( 27 ) is in the longitudinal direction of the core ( 18 ) over most of its length elongated hole. 29. Implant according to one of claims 18 to 28, characterized in that the core ( 18 ) has a side recess ( 32 ) arranged in the inserted core ( 18 ) outside of the bearing element ( 3 ). 30. Implant according to claim 29, characterized in that the recess is formed as a circumferential groove ( 32 ). 31. Implant according to one of the preceding claims, characterized in that the bearing body or bodies have at one end ( 10 ) contact surfaces ( 12 ) for a tool which rotates the bearing body ( 2 ). 32. Implant according to claim 31, characterized in that the contact surfaces are formed by a concentrically arranged, non-circular insertion opening ( 12 ) for a tool.