Interbody spinal prosthetic implant and method

• US 5,766,252 A
• Filed: 01/24/1995
• Issued: 06/16/1998
• Est. Priority Date: 01/24/1995
• Status: Expired due to Term

• Current Assignee: Howmedica Osteonics Corp. (Stryker Corporation)
• Original Assignee: Osteonics Corporation (Stryker Corporation)
• Inventors: Henry, Patrick, Doursounian, Levon
• Primary Examiner(s): Weiss, John G.
• Assistant Examiner(s): CUDDIHY, FRANCIS KEVIN
• Application Number:
  US08/379,316
• Time in Patent Office: 1,239 Days
• Field of Search: 623/16, 623/17, 623/18, 606/60, 606/61
• US Class Current: 623/17.16
• CPC Class Codes: A61B 17/1671 for the spine
• 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 2/4455 for the fusion of spinal bodies, e.g. intervertebral fusion of adjacent spinal bodies, e.g. fusion cages intervertebral discs A61F2/442
• CPC Class Codes: A61F 2/4611 of spinal prostheses
• CPC Class Codes: A61F 2002/2835 Bone graft implants for filling a bony defect or an endoprosthesis cavity, e.g. by synthetic material or biological material
• CPC Class Codes: A61F 2002/30112 Rounded shapes, e.g. with rounded corners
• CPC Class Codes: A61F 2002/30158 trapezoidal
• CPC Class Codes: A61F 2002/3028 polyhedral different from parallelepipedal and pyramidal
• CPC Class Codes: A61F 2002/30593 hollow
• CPC Class Codes: A61F 2002/30774 internally-threaded
• CPC Class Codes: A61F 2002/30777 Oblong apertures
• CPC Class Codes: A61F 2002/30789 perpendicular with respect to each other
• CPC Class Codes: A61F 2002/30904 serrated profile, i.e. saw-toothed
• CPC Class Codes: A61F 2230/0004 Rounded shapes, e.g. with rounded corners
• CPC Class Codes: A61F 2230/0026 trapezoidal
• CPC Class Codes: A61F 2230/0063 Three-dimensional shapes
• CPC Class Codes: A61F 2310/00023 Titanium or titanium-based alloys, e.g. Ti-Ni alloys
• CPC Class Codes: Y10S 606/907 Composed of particular material or coated

Abstract

An interbody spinal prosthetic implant is placed between adjacent vertebral bodies of the vertebrae of a spine to maintain a desired orientation and spacing between the adjacent vertebral bodies and support the adjacent vertebral bodies for fusion at the desired orientation and spacing, the prosthetic implant including a rigid member of biocompatible material having vertically opposite upper and lower load-bearing surfaces spaced apart a distance providing a height corresponding to the desired spacing, the rigid member having a wedge-shaped configuration in horizontal planes, the wedge-shaped configuration tapering from relatively narrower widths adjacent the front end toward relatively wider widths adjacent the rear end of the rigid body and providing the rigid body with an overall width wider than the height of the rigid body, and an ogival tip at the front end of the rigid member.

Claims

1. An interbody spinal prosthetic implant for placement between adjacent vertebral bodies of the vertebrae of a spine and seating upon confronting end plates of the adjacent vertebral bodies to maintain a desired orientation and a desired spacing between the adjacent vertebral bodies and support the adjacent vertebral bodies for fusion at the desired orientation and the desired spacing, the prosthetic implant comprising:

a rigid member of biocompatible material having vertically opposite upper and lower load-bearing surfaces spaced apart altitudinally to define a height and located along mean planes extending in generally longitudinal directions corresponding to the desired orientation, the load-bearing surfaces being spaced apart a distance corresponding to the desired spacing, the rigid member including,

a front end, a rear end spaced longitudinally from the front end to define a length, and sides spaced apart laterally to define a width, said sides extending generally longitudinally at an angle to one another to define a wedge-shaped configuration in the rigid member in horizontal planes, the wedge-shaped configuration tapering from narrower widths adjacent the front end toward wider widths adjacent the rear end and including an overall width greater than the height between the upper and lower load-bearing surfaces; and

a tip extending longitudinally between the front end and the load-bearing surfaces, the tip having a surface contour configuration tapered from transverse cross-sectional profiles of relatively lesser height and relatively narrower width adjacent the front end toward transverse cross-sectional profiles of relatively greater height and relatively wider width adjacent the load-bearing surfaces such that the surface contour configuration of the tip follows an ogival profile including a continuous curve from the front end to the load-bearing surfaces and from the front end to the sides of the rigid member.

2. The invention of claim 1 wherein the sides each have a convex arcuate surface contour configuration, in lateral planes, extending altitudinally between the upper and lower load-bearing surfaces.

3. The invention of claim 2 wherein the rigid member has a central longitudinal axis and the convex arcuate surface contour configuration of each side lies on a circle centered on the central longitudinal axis and having a diameter greater than the height of the rigid member.

4. The invention of claim 2 wherein the angle between the sides is about 4°

to about 8°

.

5. The invention of claim 1 wherein the angle between the sides is about 4°

to about 8°

.

6. The invention of claim 1 wherein the mean planes are parallel to one another.

7. The invention of claim 1 wherein the mean planes are oriented at an angle to one another such that the distance between the upper and lower load-bearing surfaces varies from a greater height adjacent the front end to a lesser height adjacent the rear end.

8. The invention of claim 7 wherein the angle between the upper and lower load-bearing surfaces is up to about 8°

.

9. The invention of claim 1 wherein the rigid member includes a maximum width intermediate the front end and the rear end, and the sides extend generally longitudinally at a further angle to one another along a further wedge-shaped configuration in horizontal planes, the further wedge-shaped configuration tapering from relatively narrower widths adjacent the rear end toward relatively wider widths adjacent the maximum width.

10. The invention of claim 9 wherein the further angle is about 40°

.

11. The invention of claim 9 wherein the maximum width is spaced from the front end about three-quarters of the length of the rigid member.

12. The invention of claim 1 wherein the rigid member includes a chamber within the rigid member for containing bone graft material, and oblong openings at the upper and lower load-bearing surfaces, the oblong openings communicating with the chamber for establishing areas of contact between the end plates and the bone graft material subsequent to placement of the prosthetic implant between the adjacent vertebral bodies.

13. The invention of claim 12 wherein the chamber is spaced rearwardly from the front end so that the tip is solid.

14. The invention of claim 12 including further oblong openings in the sides of the rigid member, the further oblong openings communicating with the chamber for further facilitating the circulation of blood to the bone graft material in the chamber.

15. The invention of claim 1 wherein the upper and lower load-bearing surfaces include laterally oriented serrations for enhancing securement of the rigid member between the adjacent vertebral bodies subsequent to placement of the rigid member between the vertebral bodies.

16. The invention of claim 1 wherein the biocompatible material is a titanium alloy.

17. The invention of claim 1 wherein the rigid member includes a rear wall at the rear end.

18. The invention of claim 17 including a threaded hole in the rear wall, the threaded hole extending longitudinally from the rear end toward the front end.

19. The invention of claim 17 wherein the rigid member comprises a unitary construction including the tip and the rear wall.

20. The invention of claim 19 wherein the biocompatible material is a titanium alloy.