Vertebral body replacement implant
View Patent ↗A vertebral body replacement implant having an upper and a lower support plate and two load-bearing elements, the mutual spacing of which is adjustable and of which at least one is connected in an articulated manner to a support plate, the load-bearing element in the region of the articulated connection to the support plate having a bearing projection with a spherical lateral support surface having a complimentary design to the contact surface of the support plate or a bearing part connected thereto, the contact surface extending in peripheral direction at least over 180°, the support plate or the bearing part is mounted on the bearing projection pivotably about a pivotal axis that extends parallel to the support plate, and a releasable clamping device that clamps the bearing projection and the support plate or the bearing part in the contact region of the lateral surface and/or of the contact surface against one another.
1. A vertebral body replacement implant comprising:
an upper and a lower support plate for positioning against end faces of vertebral bodies;
two load-bearing elements, the mutual spacing of the two load-bearing elements being adjustable;
an articulated connection between at least one of the two load-bearing elements and a corresponding one of the upper and lower support plates, the load-bearing element in a region of the articulated connection to the corresponding support plate having a bearing projection with a spherical lateral support surface,
one of the corresponding support plate or a bearing part connected to the support plate resting with a contact surface, which is of a complimentary design to the spherical lateral support surface, against the spherical lateral support surface of the bearing projection over an angular range that extends in a peripheral direction at least over 180°, the corresponding support plate or the bearing part being mounted on the bearing projection pivotably about a pivotal axis extending parallel to the support plate; and
a clamping device that clamps the bearing projection, on the one hand, and the corresponding support plate or the bearing part in a contact region of at least one of the spherical lateral support surface and the contact surface, on the other hand, towards one another,
wherein:
the support plate is of a U-shaped design having two substantially parallel limbs connected by a transverse web;
the limbs are disposed on either side of the spherical bearing projection,
the pivotal axis extends parallel to the transverse web;
the clamping device in a clamping position clamps the two limbs towards one another at their free ends remote from the transverse web; and
in the clamping position the bearing projection and the support plate or the bearing part are clamped non-pivotably relative to one another and in a release position are released so that they are freely pivotable relative to one another about the pivotal axis.
2. Implant according to claim 1 , wherein the clamping device is a clamping screw that extends parallel to the pivotal axis and rests against the free ends of the limbs.
3. Implant according to claim 2 , wherein the longitudinal axis of the clamping screw and the pivotal axis define a bearing plane that extends at a spacing from, and substantially parallel to, a supporting surface of the support plate that is positionable against a vertebral body.
4. Implant according to claim 1 , wherein the pivotal axis is defined by a bearing shaft that is adapted to be screwed into the bearing projection.
5. Implant according to claim 1 , wherein the bearing part takes the form of a bearing ring that has a dividing slot extending transversely along its circumference.
6. Implant according to claim 5 , wherein the bearing ring is disposed in a recess of the support plate and rests with its outer side against an inner wall of the recess.
7. Implant according to claim 6 , wherein the recess forms a central opening in the support plate.
8. Implant according to claim 1 , wherein the support plate in a region of the transverse web is of an elastically deformable design.
9. Implant according to claim 8 , wherein the support plate has a lower thickness in the region of the transverse web than in a region of the limbs.
10. Implant according to claim 1 , wherein the limbs and the transverse web on their outer side remote from the load-bearing elements carry laterally outwardly projecting; plate-shaped supporting surfaces that form an external contour of the support plate.
11. Implant according to claim 10 , wherein the two supporting surfaces associated with the limbs form mutually opposite, outer lateral edges of the support plate, the spacing between which edges increases from a ventral side to a dorsal side of the support plate.
12. Implant according to claim 11 , wherein the outer lateral edges of the support plate merge via arc-shaped portions into a ventral outer edge of the support plate that extends parallel to the transverse web.
13. Implant according to claim 11 , wherein the lateral edges merge via arc-shaped portions into a dorsal outer edge of the support plate.
14. Implant according to claim 11 , wherein a central region of the outer lateral edges is curved inwards.
15. Implant according to claim 14 , wherein an inwardly curved region of the outer lateral edges of the support plate is of an arc-shaped design.
16. Implant according to claim 14 , wherein an inwardly curved region of the outer lateral edges directly adjoins arc-shaped portions of the outer lateral edges, via which arc-shaped portions the outer lateral edges merge into ventral and dorsal outer edges of the support plate.
17. Implant according to claim 10 , wherein the supporting surface associated with the transverse web has in its central part an indentation that is open in a direction of a ventral outer edge of the support plate.
18. Implant according to claim 10 , wherein the supporting surfaces associated with the transverse web and the limbs jointly surround a central opening that is open in a direction of a dorsal outer edge of the support plate.
19. Implant according to claim 18 , wherein the opening is of a circular design.
20. Implant according to claim 18 , wherein the central opening via a radial slot is open in the direction of the dorsal outer edge.
21. Implant according to claim 10 , wherein in a dorsal outer edge of the support plate a central, recessed portion is disposed.
22. Implant according to claim 21 , wherein the recessed portion is of a semicircular design.
23. Implant according to claim 18 , wherein at an edge of the central opening, outwardly projecting fixing projections are disposed.
24. Implant according to claim 23 , wherein the fixing projections have a shape of thorns or points.
25. Implant according to claim 10 , wherein holes are provided in the supporting surfaces.
26. Implant according to claim 18 , wherein lateral recesses are disposed in an edge of the central opening.
27. Implant according to claim 1 , wherein the articulated connection connects both load-bearing elements to a corresponding support plate.
28. Implant according to claim 4 , wherein the bearing shaft, in a support plate with bearing parts, passes through both the bearing part and an opening in the support plate.
29. Implant according to claim 3 , wherein the clamping screw in a screw-in region is coated with titanium oxide.
30. Implant according to claim 1 , wherein the support plate is provided with a bone-friendly coating.
31. Implant according to claim 30 , wherein fixing projections of the support plate are excepted from the bone-friendly coating.