Annular nucleus pulposus replacement

1. A prosthetic nucleus pulposus replacement device comprising:

a) an outer surface having a radius and adapted to conform to an inner wall of an annulus fibrosus, and

b) an inner surface having a radius and defining a central recess,

wherein the outer and inner surfaces define a solid, deformable, load-bearing thickness therebetween, and

wherein the ratio of the radius of the inner surface to the radius of the outer surface is at least 30%.

wherein the device consists essentially of a material selected from the group consisting of a rubber and an elastomer, and

wherein the device is made of a material having a modulus of compression of between 5 MPa and 7 MPa.

2. The device of claim 1 wherein the central recess is closed.

3. The device of claim 1 further comprising upper and lower bearing surfaces.

4. The device of claim 1 wherein the central recess contains a nucleus pulposus fluid.

5. The device of claim 1 having a shape adapted to be sufficiently foldable to deliver the device through a cannula.

6. The device of claim 1 made of an anisotropic material.

7. The device of claim 1 having a posterior portion having a height, and an anterior portion having a height, and wherein the anterior height is greater than the posterior height.

8. The device of claim 1 wherein the ratio of the radius of the inner surface to the radius of the outer surface is at least 50%.

9. The device of claim 1 wherein the central recess forms a throughhole.

10. The device of claim 9 wherein the throughhole comprises at least 30 vol % of the device.

11. The device of claim 9 wherein the throughhole comprises between 75 vol % and 90 vol % of the device.

12. The device of claim 9 wherein the throughhole is filled with SIS.

13. A prosthetic nucleus pulposus replacement device having a continuous ring shape and comprising:

a) an upper surface adapted to bear against an upper endplate,

b) a lower surface adapted to bear against a lower endplate,

c) an outer surface having a radius and adapted to conform to an inner wall of an annulus fibrosus,

d) a through hole having a radius and extending from the upper surface to the lower surface, and

e) an inner surface having a radius and defining a central recess,

wherein the device consists essentially of a material selected from the group consisting of a rubber and an elastomer, and

wherein the outer and inner surfaces define a solid, deformable, load-bearing thickness therebetween,

and wherein the device is made of a material having a modulus of compression of between 5 MPa and 7 MPa.

14. The device of claim 13 wherein the central recess is closed.

15. The device of claim 13 further comprising upper and lower bearing surfaces.

16. The device of claim 13 wherein the central recess contains a nucleus pulposus fluid.

17. The device of claim 13 having a shape adapted to be sufficiently foldable to deliver the device through a cannula.

18. The device of claim 13 made of an anisotropic material.

19. The device of claim 13 having a posterior portion having a height, and an anterior portion having a height, and wherein the anterior height is greater than the posterior height.

20. The device of claim 13 wherein the ratio of the radius of the inner surface to the radius of the outer surface is at least 50%.

21. The device of claim 13 wherein the central recess forms a throughhole.

22. The device of claim 21 wherein the throughhole comprises at least 30 vol % of the device.

23. The device of claim 21 wherein the throughhole comprises between 75 vol % and 90 vol % of the device.