Functional and biocompatible intervertebral disc spacer

• US 4,911,718 A
• Filed: 06/10/1988
• Issued: 03/27/1990
• Est. Priority Date: 06/10/1988
• Status: Expired due to Term

• Current Assignee: University of Medicine and Dentistry of New Jersey (State of New Jersey)
• Original Assignee: Johnson & Johnson, Rutgers University, University of Medicine and Dentistry of New Jersey (State of New Jersey)
• Inventors: Alexander, Harold, Lee, Casey K., Clemow, Alastair J., Langrana, Noshir A., Parsons, John R., Chen, Elizabeth H.
• Primary Examiner(s): Apley, Richard J.
• Assistant Examiner(s): Isabella, David J.
• Application Number:
  US07/205,076
• Time in Patent Office: 655 Days
• Field of Search: 57/902, 623/11, 623/13, 623/12, 623/16, 623/18, 623/19, 623/20, 623/21, 623/22, 623/23
• US Class Current: 623/17.15
• CPC Class Codes: A61F 2/30724 Spacers for centering an implant in a bone cavity, e.g. in a cement-receiving cavity
• CPC Class Codes: A61F 2/30767 Special external or bone-contacting surface, e.g. coating for improving bone ingrowth
• CPC Class Codes: A61F 2/3094 Designing or manufacturing processes
• CPC Class Codes: A61F 2/30965 Reinforcing the prosthesis by embedding particles or fibres during moulding or dipping
• 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 2002/30009 differing in fibre orientations
• CPC Class Codes: A61F 2002/30016 differing in hardness, e.g. Vickers, Shore, Brinell
• CPC Class Codes: A61F 2002/30065 thermoplastic, i.e. softening or fusing when heated, and hardening and becoming rigid again when cooled
• CPC Class Codes: A61F 2002/30069 elastomeric
• CPC Class Codes: A61F 2002/30133 kidney-shaped or bean-shaped
• 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 2002/30929 having at least two superposed coatings
• CPC Class Codes: A61F 2002/30968 Sintering
• CPC Class Codes: A61F 2002/4495 having a fabric structure, e.g. made from wires or fibres
• CPC Class Codes: A61F 2210/0071 thermoplastic
• CPC Class Codes: A61F 2230/0015 Kidney-shaped, e.g. bean-shaped
• CPC Class Codes: A61F 2250/0019 differing in hardness, e.g. Vickers, Shore, Brinell
• CPC Class Codes: A61F 2250/0028 differing in fibre orientations
• CPC Class Codes: A61F 2310/00407 Coating made of titanium or of Ti-based alloys
• CPC Class Codes: A61F 2310/00796 Coating or prosthesis-covering structure made of a phosphorus-containing compound, e.g. hydroxy(l)apatite
• CPC Class Codes: A61F 2310/00952 : Coating, pre-coating or prosthesis-covering structure made of bone cement, e.g. pre-applied PMMA cement mantle

Abstract

The construction and manufacturing technique for a functional biocompatible intervertebral disc spacer is described. This device is useful for a replacement for a degenerated disc in certain treatments of back pain and spinal disease. The disc spacer possesses mechanical properties akin to those of the normal disc and will preserve normal functions of the spinal motion segment. The device achieves the desired properties by providing reinforcing fibers of appropriate orientation and number within an elastomeric matrix.

Claims

1. A biocompatible intervertebral spacer comprising:

a central core having upper, lower and side surfaces and formed of a biocompatible elastomer shaped so as to approximate the nucleus pulposus of a natural intervertebral disc.

A layered structure wrapped around the side surfaces, wherein said layered structure comprises between 3-24 separated laminae.

and each of said lamina comprised of strips of biocompatible elastomer having unidirectional reinforcing fiber embedded therein;

said fiber of each lamina having specific orientation;

said laminae being bound together by biocompatible elastomer; and

wrapped to sufficient thicknesses so as to approximate the shape of a natural intervertebral disc;

and endplates comprised of a suitably stiff biocompatible material and affixed, one to each end, to the laminae/central core.

2. A spacer according to claim 1 wherein the biocompatible elastomer utilized is a thermoset polyurethane elastomer.

3. A spacer according to claim 1 wherein the biocompatible elastomer utilized is a thermoplastic polyurethane elastomer.

4. A spacer according to claim 1 wherein the biocompatible elastomer utilized is the polyurethane elastomer Biomer.sup.®

.

5. A spacer according to claim 1 wherein the laminae wrapping the central core possess protruding fibers.

6. A spacer according to claim 1 wherein the endplates contain hydroxyapatite.

7. A spacer according to claim 1 wherein at least one of said lamina having fibers oriented at 0 degrees and at least one of the other lamina having fibers oriented at 20-50 degrees said fiber orientation in each lamina being selected from the group consisting of 0 degrees and ±

20-50 degrees.

8. A spacer according to claim 7 wherein the biocompatible elastomer utilized is a thermoset polyurethane elastomer.

9. A spacer according to claim 7 wherein the biocompatible elastomer utilized is a thermoplastic polyurethane elastomer.

10. A spacer according to claim 7 wherein the biocompatible elastomer utilized is the polyurethane elastomer Biomer.sup.®

.

11. A spacer according to claim 7 wherein the laminae wrapping the central core possess protruding fibers.

12. A spacer according to claim 7 wherein the endplates contain hydroxyapatite.

13. A spacer according to claim 7 wherein the layered structure comprises 6-15 laminae.

14. A spacer according to claim 13 wherein the biocompatible elastomer utilized is a thermoset polyurethane elastomer.

15. A spacer according to claim 13 wherein the biocompatible elastomer utilized is a thermoplastic polyurethane elastomer.

16. A spacer according to claim 13 wherein the biocompatible elastomer utilized is the polyurethane elastomer Biomer.sup.®

.

17. A spacer according to claim 13 wherein the laminae wrapping the central core possess protruding fibers.

18. A spacer according to claim 13 wherein the endplates contain hydroxyapatite.

19. A spacer according to claim 1 wherein the layered structure comprises 6-15 laminae and at least one of said lamina having fibers oriented at 0 degrees and at least one of the other lamina having fibers oriented at 45 degrees.

20. A spacer according to claim 19 wherein the biocompatible elastomer utilized is a thermoset polyurethane elastomer.

21. A spacer according to claim 19 wherein the biocompatible elastomer utilized is a thermoplastic polyurethane elastomer.

22. A spacer according t claim 19 wherein the biocompatible elastomer utilized is the polyurethane elastomer Biomer.sup.®

.

23. A spacer according to claim 19 wherein the laminae wrapping the central core possess protruding fibers.

24. A spacer according to claim 19 wherein the endplates contain hydroxyapatite.

25. A spacer according to claim 1 wherein the endplates are metal.

26. A spacer according to claim 1 wherein the endplates have a porous sintered surface.

27. A spacer according to claim 1 sized so as to approximate the size of a natural disc.

28. A spacer according to claim 1 sized so as to approximate 30-80 % of the size of a natural disc.

29. A spacer according to claim 22 wherein the laminae are arranged in a layered structure and the fiber orientation of the laminae is in a pattern of -45/+45/0 degree.