Intervertebral implant comprising dome-shaped joint surfaces

• US 20060229725A1
• Filed: 01/23/2006
• Published: 10/12/2006
• Est. Priority Date: 07/22/2003
• Status: Active Grant

• Current Assignee: Synthes USA LLC (Johnson & Johnson)
• Original Assignee: Synthes USA LLC (Johnson & Johnson)
• Inventors: Frigg, Robert, Lechmann, Beat, Burki, Roger
• Granted Patent: US 8,133,281 B2
• Time in Patent Office: Days
• US Class Current: 623/17.110
• CPC Class Codes: A61F 2/4425 made of articulated components
• CPC Class Codes: A61F 2/4611 of spinal prostheses
• CPC Class Codes: A61F 2002/30354 Cylindrically-shaped protrusion and recess, e.g. cylinder of circular basis
• CPC Class Codes: A61F 2002/30662 with rotation-limiting means
• CPC Class Codes: A61F 2002/30685 Means for reducing or preventing the generation of wear particulates
• CPC Class Codes: A61F 2002/30828 parallel
• CPC Class Codes: A61F 2002/30843 Pyramidally-shaped
• CPC Class Codes: A61F 2002/30879 Ribs
• CPC Class Codes: A61F 2002/30884 Fins or wings, e.g. longitudinal wings for preventing rotation within the bone cavity
• CPC Class Codes: A61F 2002/30892 parallel
• CPC Class Codes: A61F 2002/30904 serrated profile, i.e. saw-toothed
• CPC Class Codes: A61F 2002/3093 for promoting ingrowth of bone tissue
• CPC Class Codes: A61F 2002/443 having two transversal endplates and at least one intermediate component
• CPC Class Codes: A61F 2220/0033 made by longitudinally pushing a protrusion into a complementary-shaped recess, e.g. held by friction fit
• CPC Class Codes: A61F 2310/00023 Titanium or titanium-based alloys, e.g. Ti-Ni alloys
• CPC Class Codes: A61F 2310/00029 Cobalt-based alloys, e.g. Co-Cr alloys or Vitallium
• CPC Class Codes: A61F 2310/00293 containing a phosphorus-containing compound, e.g. apatite
• CPC Class Codes: A61F 2310/00574 Coating or prosthesis-covering structure made of carbon, e.g. of pyrocarbon
• CPC Class Codes: A61F 2310/00748 Coating made of titanium carbide

Abstract

An intervertebral implant with a central axis, a top part, a bottom part, a joint comprising a joint part and a joint shell, and a joining means. The top part has a top apposed surface that is suitable for placing it on a vertebra situated above it; The bottom part has a bottom apposed surface, that is suitable for placing it on a vertebra situated below it. One of the two parts is operatively associated with a convex joint part and the other part to a matching joint shell. The joint part and the joint shell are mounted against one another in a sliding manner such that the top part and the bottom part can rotate relative to one another at least about one axis of rotation. The joining means holds the top part and the bottom part together without impairing the capability of the joint to pivot while allowing a clearance between the joint part and the joint shell.

Claims

1. An intervertebral implant in particular an artificial intervertebral disk comprising:

a top part comprising a top apposed surface suitable for placement against a vertebra situated above and adjacent the bottom part;

a bottom part with a bottom apposed surface suitable for placement against a vertebra situated below and adjacent the bottom part;

a joint axially connecting the top part and the bottom part comprising a convex joint part with a first articular surface and a joint shell with a second articular surface mounted in a sliding manner against the first articular surface of the convex joint part, wherein either the top part or the bottom part is operatively associated with the convex joint part and the other part is operatively associated with the joint shell such that the top part and the bottom part can rotate relative to one another about at least one axis of rotation; and

a joining means by which the convex joint part and the joint shell are held to together without impairing the capability of the joint to pivot whilst permitting an axial clearance between the convex joint part and the joint shell.

2. The implant of claim 1, wherein the joining means permits a minimum clearance between the joint part and the joint shell of about 0.005 mm to about 0.05 mm.

3. The implant of claim 1, wherein the joining means permits a maximum clearance between the joint part and the joint shell of about 0.6 mm.

4. The implant of claim 1, wherein the joining means comprises an anchoring element with a first end and a second end, wherein the first end can be joined with the top part or the bottom part and the second end is loosely mounted in the other part or a structure operatively associated with the other part.

5. The implant of claim 4, wherein the second end of the anchoring element is loosely mounted in a hollow space in the convex joint part.

6. The implant of claim 5, wherein the anchoring element comprises an extension located toward the second end of the anchoring element and located in the hollow space.

7. The implant of claim 6, wherein the hollow space comprises a constriction at some point in the convex joint part.

8. The implant of claim 7, wherein the extension is located a portion of the hollow space further from the virtual apex than from the constriction.

9. The implant of claim 8, wherein the plate is of sufficient sized that it cannot pass through the constriction in the hollow space.

10. The implant of claim 1, wherein the top apposed surface and bottom apposed surface are provided with macroscopic pyramid-like protuberances.

11. The implant of claim 10, wherein the pyramid-like protuberance have a volume between about 0.12 mm³ and about 1.4 mm³.

12. The implant of claim 1, wherein the radius of the first articular surface is between about 3 mm and about 25 mm.

13. An intervertebral implant in particular an artificial intervertebral disk comprising:

a top part having a top apposed surface suitable for placement against a vertebra situated above and adjacent the bottom part;

a bottom part having a bottom apposed surface suitable for placement against a vertebra situated below and adjacent the bottom part;

a joint axially connecting the top part and the bottom part comprising a convex joint part with an articular surface, a joint shell having an articular surface mounted in a sliding manner against the articular surface of the convex joint part and a hollow space, wherein either the top part or the bottom part is operatively associated with the convex joint part and the other part is operatively associated with the joint shell such that the top part and the bottom part can rotate relative to one another about at least one axis of rotation; and

an anchoring element comprising an extension located in the hollow space and a pin operatively associated with the top part.

14. The implant of claim 13, wherein the hollow space is substantially cylindrical and coaxial with the axis of rotation of the joint.

15. The implant of claim 14, wherein the hollow space has a diameter between about 6 mm and about 20 mm.

16. The implant of claim 15, wherein the cylindrical hollow space has a height between about 0.5 mm and about 8 mm.

17. The implant of claim 13, wherein hollow space has a contraction that is coaxial with the an axis of rotation of the joint and which terminates in the articular surface of the convex joint part.

18. The implant of claim 17, wherein the contraction is substantially cylindrical.

19. The implant of claim 18, wherein the ratio of the diameter of the contraction to the ratio of the diameter of uncontracted segment of the hollow space is between about 30% and about 75%.

20. The implant of claim 13, wherein the extension is substantially circular.

21. The implant of claim 20, wherein the diameter of the extension is greater than the diameter of the contraction.

22. The implant of claim 17, wherein the diameter of the contraction and the diameter of the cylindrical hollow is sufficiently large to enable lateral movement of the pin during articulation of the joint.