EP1635743A1

EP1635743A1 - Implant for the intervertebral space

Info

Publication number: EP1635743A1
Application number: EP03729770A
Authority: EP
Inventors: Beat Lechmann; Robert Frigg; Roger BÜRKI
Original assignee: Synthes AG Chur
Current assignee: Synthes GmbH
Priority date: 2003-06-24
Filing date: 2003-06-24
Publication date: 2006-03-22
Also published as: JP2007504843A; AR044792A1; JP4378343B2; WO2004112660A1; CN1787794A; TW200505387A; BR0318328A; US8012208B2; CA2530730A1; US8617247B2; AU2003240354A1; US20060195190A1; US20110313531A1; CL2004001388A1

Abstract

The invention relates to an implant (1) for the intervertebral space, comprising a body (2) with: A) an upper contact surface (3) for resting against the base plate of a vertebral body that adjoins the implant (1) on top, a lower contact surface (4) for resting against the cover plate of a vertebral body that adjoins the implant (1) underneath; B) two lateral side surfaces (18; 19), a front and rear side surface (16, 17), and a central axis (5) that intersects the two contact surfaces (3; 4), a longitudinal axis (14) that intersects the front and the rear side surface (16; 17), and a transversal axis (15) that intersects the lateral side surfaces (18; 19), and; C) a central plane (36), which is located between the contact surfaces (3; 4) and which is perpendicular to the central axis (5) of the body (2), whereby; D) the contact surfaces (3; 4) have, at least in part, macroscopic teeth (7) with central axes (34), whereby; E) the central axes (34) of the teeth (7) are at an angle to the central plane (36) whereby promoting a rotation of the body (2) about the longitudinal axis (14) in one direction of rotation and hindering a rotation in the other direction of rotation.

Description

Implant for the intervertebral space

The invention relates to an implant for the intervertebral space, according to the preamble of patent claim 1.

Various intervertebral implants are known for use in the posterior lumbar fusion of two adjacent vertebral bodies. Such an implant for the intervertebral space is known from WO 95/08306 BECKERS. This known implant comprises a body with a lenticular profile in a plane, wherein the two convex surfaces for abutment against the deck or base of the adjacent vertebral bodies serve, so that this profile largely coincides with the biconcave shape of the sagittal section of the intervertebral space. In the other two planes, the body has parallel flat sides. Further, the body is penetrated parallel to its central axis, that is from one contact surface to the other contact surface of a through-opening, so that the body can be filled with bone material. The rounding at the front of the body and the convex contact surfaces require no mechanical processing, such as milling or Meissein the basic or cover plate of the adjacent vertebral bodies. The cross-sectional axis orthogonal to the longitudinal axis has two roundings which are attached to diagonally lying corners, so that the implant can be introduced transversely, ie with its contact surfaces transversely to the longitudinal axis of the spine into the intervertebral space and then with a suitable tool in a direction of 90 ° can be rotated until the contact surfaces of the body come into contact with the base or cover plate of the adjacent vertebral bodies. A disadvantage of this known implant is that the Kontaktfächen can be provided with a structuring, which have either parallel to the longitudinal axis grooves or transverse to the longitudinal axis grooves. Such structuring with symmetrical flanks of the teeth either directly favors or impedes the insertion of the implant into the intervertebral space and slipping it out, or prevents or impedes the rotation of the body in both directions of rotation. Another generic intervertebral implant is known from US 4,834,757 BRANTIGAN. This known intervertebral implant comprises a frame-like body which is provided on the contact surfaces as well as on the two lateral side surfaces with an asymmetric structuring, this structuring comprising sawtooth-like teeth whose flat flanks are directed against the front end of the body and thus upon insertion of the implant in The intervertebral space, the two adjacent vertebral bodies apart while the steep flanks catch and thus prevent slipping out of the implant. A disadvantage of this known implant that the teeth complicate the rotation in both directions.

The invention aims to remedy this situation. The invention has for its object to provide an implant for the intervertebral space, which allows rotation of the implant about the longitudinal axis of the body in a rotational direction and prevents in the opposite direction of rotation.

The invention solves this problem with an implant for the intervertebral space, which has the features of claim 1.

The advantages achieved by the invention are to be seen essentially in the fact that thanks to the inventive implant

- A simple implantation by simply inserting and rotating the implant is possible;

- An undesirable shift, especially slipping it out of the disc space can be prevented;

- An unwanted back rotation of the implant in the intervertebral space can be prevented; and

- Lateral slipping of the implant within the intervertebral space, in particular towards the center of the vertebral body, can be prevented. In a preferred embodiment, the macroscopic teeth are designed such that their central axes in the orthogonal to the longitudinal axis of the body considered cutting planes through the body are inclined to the median plane of the body. As a result, the advantage is achieved that the preferred, respectively the difficult direction of rotation of the implant favors the implantation of the body precisely around the longitudinal axis.

In a further embodiment, the teeth are formed such that their central axes are also inclined in orthogonal to the transverse axis through the body to the median plane, so that a preferred direction of displacement can be reached, whereby the insertion of the implant is simplified in the intervertebral space, while a Slipping is prevented.

Preferably, the teeth are formed as crooked pyramids or crooked cones, respectively oblique truncated pyramids or oblique truncated cones.

In another embodiment, the teeth are formed such that their central axes are parallel on at least one contact surface. Preferably, however, the teeth are designed so that their central axes are parallel on each of the two contact surfaces. Thus, the above-mentioned advantages will be enhanced.

In yet another embodiment, the teeth are configured such that their central axes enclose an angle + φ on the upper contact surface in the sectional planes orthogonal to the longitudinal axis and an angle φ on the lower contact surface. This achieves the advantage that the rotation of the implant in one direction of rotation about its longitudinal axis is promoted while the rotation in the other direction of rotation is made more difficult.

The height of the teeth relative to the corresponding contact surface is preferably between 0.15 mm and 1.5 mm.

In a further embodiment, the teeth each have a steep one in two mutually perpendicular, orthogonal to the central axis considered cutting planes Flank and one flank each. The teeth are thus formed substantially as inclined pyramids, whereby a turning back and a lateral migration of the implanted implant can be prevented.

In yet another embodiment, the implant consists of a radiolucent material, which may be selected, for example, from the following group:

Polyaryletherketones (PAEK), Polyetherimide (PEI), Polyosymethylene (POM), Liquid Crystalline Polymer (LCP), Polymethylpentene (PMP), Polysulfone (PSU), Polyethersulfone (PESU or PES), Polyethylene Terephthalate (PETP), Polymethylmethacrylate (PMMA) or Ultra High Molecular Weight Polyethylene (UHMW-PE);

Polymers which are reinforced by long or short fibers, for example of carbon.

By making the implant from a radiolucent material, there is the advantage that the surgeon or the radiologist can better track bone perforation.

In another embodiment, the surface of the implant is roughened, whereby advantages in Knochenanwachsverhalten can be achieved. The surface roughness is preferably between 2 μm and 10 μm. Experience has shown that bone cells grow best on the surface of the implant in this area of surface roughness.

In yet another embodiment, the flat flanks of the teeth in viewed to the transverse axis orthogonal cutting planes with an angle parallel to the central axis of the body an angle α between 30 ° and 80 ° while the steep flanks with the same straight line an angle ß between 5 ° and 30 ° lock in.

In a further embodiment, the flat flanks of the teeth close on the upper contact surface in the orthogonal to the longitudinal axis sectional planes with to Central axis of the body parallel lines an angle γ between + 30 ° and + 80 ° while the steep flanks with the central axis of the body include an angle δ between + 5 ° and + 30 °. On the lower contact surface, the angles γ are between -30 ° and -80 ° and the angles δ between -5 ° and -30 °.

The above-mentioned flank angles of the teeth are advantageous for setting the teeth in the end plates of the adjacent vertebral bodies.

Preferably, the angles .alpha. And .gamma. Of the flat flanks and the angles .beta. And .delta. Of the steep flanks are the same, so that the resistance of the teeth optimally counteracts boring or migration.

The geometry of the teeth is preferably formed in such a manner that the volume V of a survey of between 0.15 mm ³ and 1, 2 mm ³ is. Preferably, the contact surfaces are completely provided with teeth.

In a further embodiment, the steep flanks of the teeth are arranged in parallel planes. This achieves optimal resistance to screwing out or migration of the implant.

In yet another embodiment, the cuboid body is formed such that the orthogonal to the longitudinal axis, second cross-sectional area is rectangular and has a one-sided rounding. The advantage of this embodiment is that the rotation of the implant can be made only in one direction and on the opposite side of the rounding the contact surface can be used for attaching additional teeth. Thus, the number of teeth can still be kept high.

In another embodiment, the radius of the rounding is dimensioned such that the contact surface to the bone is reduced by the rounding by less than half, preferably by less than one third, so that the number of teeth on the contact surfaces can be kept high. In yet another embodiment, the cuboid body is formed such that the orthogonal to the longitudinal axis, the second cross-sectional area is rectangular and has two diagonally mounted rounded portions. This makes it easier to manually rotate the implant during the operation.

In a further embodiment, the radii of the two fillets are dimensioned such that the second cross-sectional area of the body is reduced by less than half, preferably by less than a quarter. The advantage of this embodiment lies in the high structural strength of the implant, which can be achieved despite the rounding, i. as little material as possible is left out in order to realize the rounding off.

In yet another embodiment, the fillets are elliptical. The elliptical shape allows for easy starting during implant rotation. The resistance against the rotation is built up during the turning process, so that in the end position the resistance against turning back becomes maximum.

In another embodiment, the fillets have two different radii of curvature. The larger radius adjacent to the side surfaces simplifies implant rotation at the beginning. As a result of the smaller radius adjacent to the contact surfaces, the rotational resistance is increased, so that in the end position the resistance to reverse rotation becomes maximum.

Preferably, the body having first and second lateral side surfaces intersecting the contact surfaces and the front side surface has fillets disposed diagonally between the first lateral side surface and the upper contact surface and between the second lateral side surface and the lower contact surface.

In yet another embodiment, the body has second fillets disposed between the front side surface intersecting the contact surfaces and the contact surfaces. The advantage of these second roundings is that that, unlike sharp edges, the bony structure of the adjacent vertebral bodies is not damaged. In addition, the rounding during insertion of the implant in the intervertebral space favor the displacement of the implant and prevent sticking.

In a further embodiment, the implant comprises at least one, but preferably a plurality of X-ray markers. This provides the advantage that the position and orientation of the implant in the intervertebral space is visible intraoperatively or postoperatively in X-ray images. Advantageously, the number of X-ray marking is between one and six depending on the use of the implant.

In yet another embodiment, the body has at least one bore, so that an x-ray marker formed as a pin can be pressed into the bore. The pen is made of a radiopaque material. Preferably, the at least one bore is arranged in the implant such that its bore axis is parallel to the central axis and lies in a plane spanned by the central axis and the longitudinal axis.

In another embodiment, the at least one pin comprises peripherally and axially centrally arranged at least one radially projecting nubs, which is plastically deformed when the pin is pressed into the bore, so that the pin is fixed by means of a press fit in the bore.

In yet another embodiment, the pin is made of a metal, preferably steel, titanium, tantalum or gold.

The invention and further developments of the invention will be explained in more detail below with reference to the partially schematic representations of several embodiments.

Show it: Fig. 1 is a perspective view of an embodiment of the inventive implant;

FIG. 2 shows a first cross section through the embodiment of the implant according to the invention shown in FIG. 1; FIG.

3 shows a longitudinal section through the embodiment of the implant according to the invention shown in FIGS. 1 and 2 with means for receiving a holding instrument;

4 shows a longitudinal section through an embodiment of the implant according to the invention with X-ray markings; and

Fig. 5 is a plan view of the rear end of the embodiment of the inventive implant shown in Fig. 4.

1 to 3, an embodiment of the implant 1 is shown, which a cuboid body 2 with an upper and a lower convex contact surface 3, 4 for abutment with the basic resp. Cover surface of the two adjacent vertebrae and a the contact surfaces 3, 4 intersecting central axis 5 comprises. Arranged transversely to the contact surfaces 3, 4 are two lateral side surfaces 18; 19, and a front side surface 16 and a rear side surface 17. The orthogonal to the central axis 5 longitudinal axis 14 intersects the two side surfaces 16; 17 while the transverse axis 15, which is also orthogonal to the central axis 5 of the body 2, intersects the two lateral side surfaces 18, 19. The longitudinal axis 14 and the transverse axis 15 define a center plane 6 which is orthogonal to the central axis 5 between the contact surfaces 3, 4.

The body 2 is penetrated parallel to its central axis 5 from the upper contact surface 3 to the lower contact surface 4 of an opening 20. Parallel to the transverse axis 15, the body 2 is penetrated by three perforations 21 from the first lateral side surface 18 to the second lateral side surface 19. The body 2 thus has a frame-like shape with a central cavity, wherein the front and the rear side surface 16; 17 no holes opening into the cavity or openings. Through the central axis 5 of the body and the longitudinal axis 14, a first cross-sectional area 10 is defined, the cutting line coincides with the second, defined by the central axis 5 of the body 2 and the transverse axis 15 cross-sectional area 11 with the central axis 5 of the body 2.

The contact surfaces 3, 4 are equipped with teeth 7 whose central axes 34 are inclined with respect to the median plane 36 of the body 2. In this case, the teeth 7 are designed such that their central axes 34 in the longitudinal axis 14 orthogonal considered cutting planes through the body 2 on the upper contact surface 3 an angle + φ and on the lower contact surface 4 an angle -φ with the median plane 36 include. The teeth 7, when viewed in the sectional plane parallel to the first cross-sectional area 10, each have a steep and a flat flank 8; 9 and, viewed in sectional planes parallel to the second cross-sectional area 11 per contact surface 3; 4 rectified one steep and one flat flank 12; 13 on, where

viewed in the sectional planes parallel to the first cross-sectional area 10, the steep flanks 8 enclose an angle β with a straight line parallel to the central axis 5 of the body 2;

the flat flanks 9, viewed in the sectional planes parallel to the first cross-sectional area 10, enclose an angle α with a straight line parallel to the central axis 5 of the body 2;

the steep flanks 12 in the sectional planes parallel to the second cross-sectional area 11, with an axis parallel to the central axis 5 of the body 2, form an angle + δ on the upper contact surface 3 and an angle -δ on the lower contact surface 4; and

the flat flanks 13 in the sectional planes parallel to the second cross-sectional area 11, with an axis parallel to the central axis 5 of the body 2, form an angle + γ on the upper contact surface 3 and an angle -γ on the lower contact surface 4.

The steep flanks 8 lie at both contact surfaces 3, 4 on the side of the teeth 7 facing the rear side surface 17. In the second cross-sectional surface 11, the steep flanks 12 of the teeth 7 are parallel to the upper contact surface 3 Longitudinal axis 14 as viewed from the front side surface 16 disposed on the right side of the teeth 7, while the steep edges 12 of the teeth 7 on the lower contact surface 4 are also arranged parallel to the longitudinal axis 14 from the front side surface 16 on the left side of the teeth 7 ,

In the embodiment illustrated here, the angles β and δ between the steep flanks 8; 12 and parallel to the central axis 5 straight lines. Similarly, the angles α and γ between the flat flanks 9; 13 and parallel to the central axis 5 of the body 2 straight lines.

The arrangement of the steep flanks 8 in the first cross-sectional area 10 is such that when the implant 1 is inserted with the front side surface 16 ahead in an intervertebral space, the basic resp. Cover plate of the adjacent vertebral bodies are pressed apart by the flat flanks 9 of the teeth 7, while any slipping out of the implanted body 2 by the steep flanks 8 is prevented. Furthermore, the arrangement of the steep flanks 12 in the second cross-sectional area 11 is such that during a clockwise rotation of the inserted into the intervertebral space implant 1, the basic resp. Cover plate of the adjacent vertebral bodies are pressed apart by the flat flanks 13 of the teeth 7, while a left-hand rotation of the implanted body 2 is prevented by the steep flanks 12.

The body 2 has to simplify the clockwise rotation during implantation between the contact surfaces 3, 4 and the lateral side surface 18; 19 roundings 23 with two different radii on. The rounded portions 23 are arranged such that they lie only in a diagonal in the second, to the longitudinal axis 14 orthogonal cross-sectional area 11, so that the rounded portions 23 between the upper contact surface 3 and the first lateral side surface 18 and between the lower contact surface 4 and the second lateral side surface 19 are arranged. With respect to the teeth 7 on the two contact surfaces 3, 4 are the rounded portions 23 on the side with the flat flanks 9; 13 attached. Likewise, the body 2 has second rounded portions 24 for easier insertion of the implant 1 into the intervertebral space between the contact surfaces 3, 4 and the front side surface 16. Furthermore, the implant 1 comprises at its rear end 28 arranged means 22 for the rotationally fixed reception of the holding instrument. In the embodiment shown in FIG. 3, these means 22 for receiving a holding instrument comprise a bore 25, which is coaxial with the longitudinal axis 14 and has an internal thread 26, which penetrates from the rear side face 17 of the implant 1. Thus, the holding instrument is rotatably connected to the implant 1, a likewise from the rear side surface 17 penetrating, parallel to the transverse axis 15 extending channel 27 is attached to the implant 1. For rotationally fixed connection between the holding instrument and the implant 1, a segment of the holding instrument provided with an external thread is screwed into the internal thread 26 and then a segment 27 complementary to the channel is inserted into the channel 27.

Description of the surgical procedure:

In order for the surgeon to be able to penetrate into the disc space with the instruments necessary for the operation, first the adjacent facet joints and the laminae are partially removed. Subsequently, the required size of the implant 1 is determined by means of test specimens. The selected in this way implant 1 is connected to the corresponding, attachable to the rear end 28 of the implant 1 holding instrument (not shown). The insertion of the implant 1 is such that the lateral, not provided with teeth 7 side surfaces 18; 19 are aligned parallel to the deck or base of the adjacent vertebral bodies. Due to the partially resected dorsal structures of the vertebral bodies, the implant 1 can then be introduced into the intervertebral space. After the implant 1 has been inserted to the desired depth in the intervertebral space, the surgeon rotates the implant 1 by 90 ° about the longitudinal axis 15 by means of the holding instrument, so that the contact surfaces 3, 4 provided with teeth 7 are fixed to the cover or base plate , With the rotation of the implant 1, the surgeon achieves a distraction in the anterior structures of the spine. Thus, among other things, the lordosis can be restored. Finally, with the same operation steps, a second implant 1 is introduced, so that an implant 1 is arranged on both sides of the spinal cord.

The embodiment of the implant 1 according to the invention shown in FIGS. 4 and 5 comprises two x-ray markings 35. These x-ray markings 35 are in the form of pins 31 formed, which are introduced into bores 32. For fixing the pins 31 in the holes 32, the pins 31 are peripherally and preferably axially centrally provided with three nubs 30. The nubs 30 are plastically deformed during the pressing of the pins 31 into the bores 32, so that the pins 31 are held in the bores 32 by means of a press fit. In the embodiment shown here, the body 2 has two bores 32, of which one bore 32 at the front end 29 of the implant 1 and the other bore 32 at the rear end 28 of the implant 1 are arranged. The bores 32 are configured such that their bore axes 33 are parallel to the central axis 5 and lie in a plane spanned by the central axis 5 and the longitudinal axis 14.

Claims

1. implant (1) for the intervertebral space comprising a body (2) with

A) an upper contact surface (3) for contacting the base plate of a vertebral body adjacent above the implant (1), a lower contact surface (4) for contacting the cover plate of a vertebral body adjacent to the implant (1);

B) two lateral side surfaces (18; 19), a front and a rear side surface (16; 17) and a central axis (5) intersecting the two contact surfaces (3; 4), one the front and the rear side surface (16; 17) intersecting longitudinal axis (14) and a transverse axis (15) intersecting the lateral side surfaces (18; 19); and

C) a central plane (36) lying between the contact surfaces (3; 4) and perpendicular to the central axis (5) of the body (2); in which

D) the contact surfaces (3; 4) have at least partially macroscopic teeth (7) with central axes (34), characterized in that

E) the central axes (34) of the teeth (7) are inclined to the central plane (36) such that rotation of the body (2) around the longitudinal axis (14) is favored in one direction of rotation and is made more difficult in the other direction of rotation.

2. Implant (1) according to claim 1, characterized in that the central axes (34) of the teeth (7) in cross-sectional planes viewed orthogonal to the longitudinal axis (14) through the body (2) are inclined to the central plane (36).

3. Implant (1) according to claim 1 or 2, characterized in that the central axes (34) of the teeth (7) are also oblique to the median plane (36) in sectional planes viewed orthogonally to the transverse axis (15) through the body (2).

4. Implant (1) according to one of claims 1 to 3, characterized in that the teeth (7) are designed as oblique pyramids or oblique cones, respectively oblique truncated pyramids or oblique truncated cones.

5. Implant (1) according to one of claims 1 to 4, characterized in that the central axes (34) of the teeth (7) on at least one contact surface (3; 4) are essentially parallel.

6. Implant (1) according to one of claims 1 to 5, characterized in that the central axes (34) of the teeth (7) in the plane of intersection of the body (2) orthogonal to the longitudinal axis (14) viewed on the upper contact surface (3) Include angle + φ and on the lower contact surface (4) an angle -φ with the central plane (36).

7. Implant (1) according to one of claims 1 to 6, characterized in that the height of the teeth (7) is between 0.15 mm and 1.5 mm.

8. The implant (1) according to any one of claims 1 to 7, characterized in that the teeth (7) in two mutually perpendicular, orthogonal to the central axis (5) of the body (2) considered planes each have a steep flank (8; 12 ) and each have a flat flank (9; 13).

9. Implant (1) according to one of claims 1 to 8, characterized in that the implant (1) consists of an X-ray transparent material.

10. Implant (1) according to one of claims 1 to 9, characterized in that the surface of the implant (1) is roughened.

11. The implant (1) according to claim 10, characterized in that the surface roughness is between 2 μm and 10 μm.

12. Implant (1) according to any one of claims 8 to 11, characterized in that the flat flanks (9) in the plane of intersection orthogonal to the transverse axis (15) viewed with an angle α and straight lines parallel to the central axis (5) of the body (2) the steep flanks (8) enclose an angle ß with the same straight lines.

13. Implant (1) according to one of claims 8 to 12, characterized in that a) on the upper contact surface (3) the flat flanks (13) in the longitudinal axis (14) orthogonal cutting planes viewed with the central axis (5) of the body (2) parallel lines form an angle + γ and the steep flanks (12) with the same straight lines form an angle + δ; and b) on the lower contact surface (4), the flat flanks (13) in the plane of intersection orthogonal to the longitudinal axis (14) viewed with straight lines parallel to the central axis (5) of the body (2) an angle γ and the steep flanks (12) with the same Include a straight line at an angle -δ

14. Implant (1) according to claim 13, characterized in that the angles and γ of the flat flanks (9; 13) are the same size.

15. Implant (1) according to claim 13 or 14, characterized in that the angles β and δ of the steep flanks (8; 12) are the same size.

16. Implant (1) according to one of claims 13 to 15, characterized in that the angles α and γ of the flat flanks (9; 13) are between 30 ° and 80 °.

17. The implant (1) according to any one of claims 13 to 16, characterized in that the angles β and δ of the steep flanks (8; 12) are between 5 ° and 30 °.

18. Implant (1) according to one of claims 1 to 17, characterized in that the volume V mm a tooth (7) is between 0.15 ³ and 1, 2 mm ³ is.

19. Implant (1) according to one of claims 8 to 18, characterized in that the steep flanks (8; 12) of the teeth (7) lie in parallel planes.

20. The implant (1) according to any one of claims 1 to 19, characterized in that the body (2) in a cross-sectional area (11) orthogonal to the longitudinal axis (14) is rectangular when viewed with a one-sided rounding (23).

21. The implant (1) according to claim 20, characterized in that the radius of the rounding (23) is dimensioned such that the contact area to the bone is reduced by the rounding (23) by less than half, preferably by less than a third .

22. The implant (1) according to any one of claims 1 to 21, characterized in that the body (2) in a cross-sectional area (11) orthogonal to the longitudinal axis (14) is rectangular when viewed with two diagonally attached roundings (23).

23. The implant (1) according to claim 22, characterized in that the radii. the two roundings (23) are dimensioned such that the second cross-sectional area (11) of the body (2) is reduced by less than half, preferably by less than a quarter.

24. Implant (1) according to one of claims 20 to 22, characterized in that the rounded portions (23) are elliptical.

25. Implant (1) according to one of claims 20 to 23, characterized in that the rounded portions (23) have two different radii of curvature.

26. Implant (1) according to one of claims 1 to 25, characterized in that the body (2) has a first and a second lateral side surface (18; 19) which the contact surfaces (3; 4) and the front side surface ( 16), and that the body (2) has diagonally rounded portions (23) between the first lateral side surface (18) and the upper contact surface (3) and between the second lateral side surface (19) and the lower contact surface (4).

27. Implant (1) according to one of claims 1 to 26, characterized in that the body (2) has a front side surface (16) intersecting the contact surfaces (3; 4) and between this and the contact surfaces (3; 4) has second roundings (24).

28. Implant (1) according to one of claims 1 to 29, characterized in that it comprises at least one X-ray marking (35).

29. The implant (1) according to claim 28, characterized in that it comprises a plurality of X-ray markings (35).

30. The implant (1) according to claim 28 or 29, characterized in that the body (2) has at least one bore (32) and the X-ray marking (35) has a pin (31) made of a radiopaque material that can be pressed into the bore (32) includes.

31. Implant (1) according to claim 30, characterized in that at least one bore (32) has a bore axis (33) which is parallel to the central axis (5) and in one through the central axis (5) and the longitudinal axis (14) spanned level.

32. Implant (1) according to claim 30 or 31, characterized in that a pin (31) arranged peripherally and axially in the center comprises at least one radially projecting knobs (30).

33. Implant (1) according to one of claims 30 to 32, characterized in that the pin (31) is made of a metal, preferably steel, titanium, tantalum or gold.

34. Implant (1) according to one of claims 1 to 33, characterized in that the contact surfaces (3; 4) are completely provided with teeth (7).