Intervertebral prosthetic disc
A prosthetic disc for insertion between adjacent vertebrae includes upper and lower plates, a core disposed between the plates, and at least one projection extending from at least one of the upper and lower curved surfaces of the core into at least one recess of one of the inner surfaces of the plates. The recess is oversize with respect to the projection to allow sliding movement of the plate over the core while retaining the core between the plates during such sliding movement. The projection(s) may include a rod extending through an axial hole in the core, multiple surface features of the core, or the like.
1. An intervertebral prosthetic disc for insertion between adjacent vertebrae, the disc comprising:
upper and lower plates having outer surfaces locatable against the respective vertebrae, inner curved surfaces, and lateral portions;
a core between the plates, the core having upper and lower curved surfaces complementary in shape to the inner, curved surfaces of the plates to allow the plates to slide over the upper and lower surfaces of the core;
wherein at least one of the curved surfaces of the plates and at least one of the curved surfaces of the core include annular formations which cooperate with one another to retain the core between the plates when the plates slide over the upper and lower surfaces of the core, such formations including an annular recess and an annular projection received by the recess; and
wherein the lateral portions of the upper and lower plates are adapted to contact one another during sliding movement of the plates over the core.
2. The prosthetic disc as in claim 1 , wherein the recess and the projection-are located between a central axis of the relevant curved surface and an outer periphery thereof.
3. The prosthetic disc as in claim 1 , wherein the projection locates within the recess with clearance.
4. The prosthetic disc as in claim 3 , wherein at a limit of sliding movement the projection abuts against a side of the recess.
5. The prosthetic disc as in claim 1 , further including at least one fin extending from each of the outer surfaces of the plates.
6. The prosthetic disc as in claim 5 , wherein each fin is oriented in a straight line in an anterior-posterior direction.
7. The prosthetic disc as in claim 5 , wherein each fin is rotated away from an anterior-posterior axis of the disc.
8. The prosthetic disc as in claim 1 , wherein the lateral portions of the upper and lower plates comprise lateral edge portions.
9. The prosthetic disc as in claim 1 , wherein the outer surfaces of the plates are textured to enhance attachment of the plates to the vertebrae.
10. The prosthetic disc as in claim 9 , wherein the textured surfaces comprise multiple serrations.
11. The prosthetic disc as in claim 1 wherein the lateral portions of the upper and lower plates comprise outer peripheries of the curved surfaces and wherein the plates are adapted to contact one another at the outer peripheries of the curved surfaces.
12. An intervertebral prosthetic disc for insertion between adjacent vertebrae, the disc comprising:
upper and lower plates having outer surfaces locatable against the respective vertebrae, inner curved surfaces, and lateral portions, wherein at least one of the inner curved surfaces of the plates comprises an inwardly directed annular rib;
a core between the plates, the core having upper and lower curved surfaces complementary in shape to the inner, curved surfaces of the plates to allow the plates to slide over the core, wherein at least one of the upper and lower curved surfaces of the core comprises an annular channel adapted to receive the annular rib;
wherein the annular rib cooperates with the annular channel to retain the core between the plates when the plates slide over the core; and
wherein the lateral portions of the upper and lower plates are adapted to contact one another during sliding movement of the plates over the core.
13. The prosthetic disc of claim 12 wherein the annular channel and the annular rib are located between a central axis of the relevant curved surface and an outer periphery thereof.
14. The prosthetic disc as in claim 12 , wherein the rib locates within the channel with clearance.
15. The prosthetic disc as in claim 14 , wherein at a limit of sliding movement the rib abuts against a side of the channel.
16. The prosthetic disc as in claim 12 , further including at least one fin extending from each of the outer surfaces of the plates.
17. The prosthetic disc as in claim 16 , wherein each fin is oriented in a straight line in an anterior-posterior direction.
18. The prosthetic disc as in claim 16 , wherein each fin is rotated away from an anterior-posterior axis of the disc.
19. The prosthetic disc as in claim 12 , wherein the lateral portions of the upper and lower plates comprise lateral edge portions.
20. The prosthetic disc as in claim 12 , wherein the outer surfaces of the plates are textured to enhance attachment of the plates to the vertebrae.
21. The prosthetic disc as in claim 20 , wherein the textured surfaces comprise multiple serrations.
22. The prosthetic disc as in claim 12 wherein the lateral portions of the upper and lower plates comprise outer peripheries of the curved surfaces and wherein the plates are adapted to contact one another at the outer peripheries of the curved surfaces.