Height-adjustable intervertebrae implant
An intervertebral implant for insertion between two vertebrae is disclosed. A first part has a first contact surface extending between its two ends a first guide surface extending out from the first contact surface. A second part has a second contact surface extending between its ends, and a second guide surface recessed into the second contact surface. The first guide surface and the second guide surface cooperate so that the first contact surface of the first part can slide relative to the second contact surface of the second part with a translation motion guided by the cooperating structures of the first and second guide surfaces. The height of the intervertebral implant can be altered by shifting the first part and the second part relative to each other by moving the contact surfaces relative to each other by using the cooperating guide surfaces.
1. An intervertebral implant comprising:
a first part having a first end, a second end, a first contact surface provided between the first and second ends, a first guide surface fixed to the first contact surface and extending out from the first contact surface, and a first base surface opposite to said first contact surface;
a second part having a third end, a fourth end, a second contact surface provided between the third and fourth ends, a second guide surface fixed to the second contact surface and recessed into the second contact surface, and a second base surface opposite to said second contact surface;
the first guide surface and the second guide surface comprising cooperating structures so that the first contact surface of the first part can slide relative to the second contact surface of the second part with a translation motion guided by the cooperating structures of the first and second guide surfaces;
wherein the first contact surface is slidable relative to the second contact surface between a first position wherein the first end of the first part is connected with the third end of the second part and a second position wherein the first end of the first part is connected with the fourth end of the second part; and
wherein a distance between the first base surface and the second base surface continuously increases while the first base surface remains generally parallel with the second base surface as the first contact surface slides relative to the second contact surface from the first position to the second position.
2. The intervertebral implant according to claim 1 , wherein a first plane parallel to said first contact surface intersects a second plane parallel to said first base surface forming an inclination angle of contact α; and
wherein a third plane parallel to said second contact surface intersects a fourth plane parallel to said second base surface forming an inclination angle of contact α.
3. The intervertebral implant according to claim 2 , wherein said implant comprises a material and said angle a is determined based on the material and the surface properties of the first and second contact surfaces such that a self-locking mechanism between the first part and the second part is effected.
4. The intervertebral implant according to claim 3 , wherein the ridge comprises a first cross-section and the groove comprises a second cross-section, the first cross-section comprising a shape selected from the group comprising a dovetail-shape, a T-shape, a rectangle, a square or a semicircle, and the second cross-section comprises a complementary shape to the first cross-section shape such that the ridge and groove cooperate.
5. The intervertebral implant according to claim 1 , wherein the first and second contact surfaces and the first and second guide surfaces comprise an arcuate shape.
6. The intervertebral implant according to claim 1 , wherein said first and second parts are straight.
7. The intervertebral implant according to claim 1 , further comprising a terminal stop.
8. The intervertebral implant according to claim 1 , wherein one of the first guide surface and the second guide surface comprises a ridge and the other of the first guide surface and the second guide surface comprises a groove.
9. The intervertebral implant according to claim 8 , wherein the first and second contact surfaces, the ridge and the groove each comprise an arcuate shape.
10. The intervertebral implant according to claim 8 , wherein the groove is located in the second contact surface and extends from the third end to a pre-set distance from the fourth end of the second contact surface, thereby providing a terminal stop.
11. The intervertebral implant according to claim 1 , said implant further comprising an orifice or a recess.
12. The intervertebral implant according to claim 1 , wherein the first contact surface and/or the second contact surface comprise a roughened surface or a step-like surface.
13. The intervertebral implant according to claim 1 , wherein the first part comprises a first base surface and the second part comprises a second base surface, wherein at least one of first and second base surfaces comprise groove-shaped recesses.
14. The intervertebral implant according to claim 1 , wherein said first part and said second part are formed from a polymer.
15. The intervertebral implant according to claim 14 , wherein said polymer is polyetheretherketone.
16. The intervertebral implant according to claim 14 , wherein said polymer is polytetrafluoroethylene.
17. The intervertebral implant according to claim 1 , wherein said first and second part are formed from a body compatible metal or metal alloy.