Intervertebral disc prosthesis with improved mechanical behavior

• US 6,733,532 B1
• Filed: 07/20/2001
• Issued: 05/11/2004
• Est. Priority Date: 12/11/1998
• Status: Expired due to Fees

• Current Assignee: Stryker European Operations Holdings, LLC (Stryker Corporation)
• Original Assignee: Stryker Spine
• Inventors: Le Couedic, Régis, Gauchet, Fabien
• Primary Examiner(s): Lucchesi, Nicholas D.
• Assistant Examiner(s): Thanh, Quang D
• Application Number:
  US09/857,726
• Time in Patent Office: 1,026 Days
• Field of Search: 623/17.11, 623/17.12, 623/17.13, 623/17.14, 623/17.15, 623/17.16, 606/61, 606/72, 606/73, 606/86, 606/87
• US Class Current: 623/17.12
• CPC Class Codes: A61B 17/86 Pins or screws or threaded wires; nuts therefor A61B17/72 take precedence
• CPC Class Codes: A61F 2/30742 Bellows or hose-like seals; Sealing membranes A61B17/8808 takes precedence; sealing membranes for retaining bone substitute A61F2/2846
• CPC Class Codes: A61F 2/442 Intervertebral or spinal discs, e.g. resilient non-disc-shaped intervertebral inflatable pockets A61F2/441; non-disc-shaped intervertebral fusion implants A61F2/4455
• CPC Class Codes: A61F 2/4425 made of articulated components
• CPC Class Codes: A61F 2002/30133 kidney-shaped or bean-shaped
• CPC Class Codes: A61F 2002/30448 using adhesives
• CPC Class Codes: A61F 2002/30474 using an intermediate sleeve interposed between both prosthetic parts to be coupled
• CPC Class Codes: A61F 2002/30528 Means for limiting said movement
• CPC Class Codes: A61F 2002/30563 having elastic means or damping means, different from springs, e.g. including an elastomeric core or shock absorbers
• CPC Class Codes: A61F 2002/30578 having apertures, e.g. for receiving fixation screws
• CPC Class Codes: A61F 2002/443 having two transversal endplates and at least one intermediate component
• CPC Class Codes: A61F 2220/0025 Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
• CPC Class Codes: A61F 2220/005 using adhesives
• CPC Class Codes: A61F 2230/0015 Kidney-shaped, e.g. bean-shaped
• CPC Class Codes: Y10S 606/907 Composed of particular material or coated
• CPC Class Codes: Y10S 606/91 Polymer

Abstract

An intervertebral disc prosthesis comprising two plates and a cushion interposed between the plates is contemplated. The cushion includes a compressible body having two ends in contact with the plates. At least one of the ends is freely displaceable relative to the plate in a parallel direction. Thus, the prosthesis imitates and approximates the mechanical properties of a healthy natural intervertebral disc.

Claims

1. Intervertebral disc prosthesis comprising:

two plates having inner faces; and

a cushion interposed between the plates, the cushion comprising an elastic body having ends in contact with the inner faces of the plates, wherein at least one of the ends is freely displaceable relative to the associated plate in a direction parallel to the plate, and wherein, prior to loading, the at least one of the ends has a radius of curvature less than that of the inner face of the associated plate.

2. Prosthesis according to claim 1, wherein at least one end of the body is lodged in a recess provided in one of the plates forming a lateral abutment for the at least one end.

3. Prosthesis according to claim 1, wherein at least one end has a face having a zone of contact with a face of the associated plate, wherein the zone of contact has a surface area which increases when a stressing of the plate in the direction of the body increases.

4. Prosthesis according to claim 1, wherein at least one end has a face in contact with a face of the associated plate and the end face and the plate face are curved in at least one common direction being respectively convex and concave.

5. Prosthesis according to claim 1, wherein the body comprises a viscoelastic material.

6. Prosthesis according to claim 1, further comprising a fluid interposed between the plates.

7. Prosthesis according to claim 6, wherein the fluid is in contact with the plates.

8. Prosthesis according to claim 7, wherein the fluid extends about the periphery of the body.

9. Prosthesis according to claim 8, further comprising a chamber extending about the periphery of the body and enclosing the fluid, wherein a surface area of a transverse section of the chamber parallel to the plates is substantially invariable when a stress moving the plates toward one another varies.

10. Prosthesis according to claim 1, wherein the prosthesis is an intervertebral lumbar disc prosthesis.

11. Prosthesis according to claim 5, wherein the viscoelastic material is silicone.

12. Intervertebral disc prosthesis comprising:

two plates;

a cushion interposed between the plates, the cushion comprising a compressible body having ends in contact with the plates, wherein at least one of the ends is freely displaceable relative to the associated plate in a direction parallel to the plate;

a fluid interposed between the plates, the fluid being in contact with the plates; and

a chamber extending about the periphery of the body and enclosing the fluid.

13. Prosthesis according to claim 12, wherein at least one end of the body is lodged in a recess provided in one of the plates forming a lateral abutment for the at least one end.

14. Prosthesis according to claim 12, wherein at least one end has a face having a zone of contact with a face of the associated plate, wherein the zone of contact has a surface area which increases when a stressing of the plate in the direction of the body increases.

15. Prosthesis according to claim 12, wherein at least one end has a face in contact with a face of the associated plate and the end face and the plate face are curved in at least one common direction being respectively convex and concave.

16. Prosthesis according to claim 12, wherein the body comprises a viscoelastic material.

17. Prosthesis according to claim 16, wherein the viscoelastic material is silicone.

18. Prosthesis according to claim 12, wherein the fluid extends about the periphery of the body.

19. Prosthesis according to claim 18, wherein a surface area of a transverse section of the chamber parallel to the plates is substantially invariable when a stress moving the plates toward one another varies.

20. Prosthesis according to claim 12, wherein the prosthesis is an intervertebral lumbar disc prosthesis.

21. Intervertebral disc prosthesis comprising:

two plates having inner faces;

a cushion interposed between the plates; and

a chamber extending about the periphery of the cushion;

wherein the cushion comprises a compressible body having ends in contact with the inner faces of the plates;

at least one of the ends is freely displaceable relative to the associated plate in a direction parallel to the plate; and

prior to loading, the at least one of the ends has a radius of curvature less than that of the inner face of the associated contacting plate.

22. The prosthesis according to claim 21, wherein at least one end has a face having a zone of contact with a face of the associated plate, and the zone of contact has a surface area which increases when a stressing of the plate in the direction of the body increases.

23. The prosthesis according to claim 21, further comprising a liquid within the chamber.