Artificial spinal disc

• US 6,533,818 B1
• Filed: 07/26/2000
• Issued: 03/18/2003
• Est. Priority Date: 04/26/2000
• Status: Expired due to Fees

• Current Assignee: Pearl Corporation (Pearl Corporation of Australia Pty Limited)
• Original Assignee: Pearl Technology Holdings LLC
• Inventors: Da Silva, Luiz B., Weber, Paul J.
• Primary Examiner(s): Isabella, David J.
• Assistant Examiner(s): Phan, Hieu
• Application Number:
  US09/625,440
• Time in Patent Office: 965 Days
• Field of Search: 623/17.11, 623/17.12, 623/17.13, 623/17.16, 623/23.41, 623/23.5, 623/23.51, 623/23.52
• US Class Current: 623/17.16
• CPC Class Codes: A61F 2/30767 Special external or bone-contacting surface, e.g. coating for improving bone ingrowth
• CPC Class Codes: A61F 2/441 made of inflatable pockets or chambers filled with fluid, e.g. with hydrogel
• 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 2002/30006 differing in density or specific weight
• 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 2002/30581 having a pocket filled with fluid, e.g. liquid
• CPC Class Codes: A61F 2002/30733 Inserts placed into an endoprosthetic cavity, e.g. for modifying a material property
• CPC Class Codes: A61F 2002/30879 Ribs
• CPC Class Codes: A61F 2250/0015 differing in density or specific weight
• CPC Class Codes: A61F 2310/00365 Proteins; Polypeptides; Degradation products thereof

Abstract

A multi layered artificial spinal disc that can be surgically implanted to replace a damaged natural spinal disc. The top and bottom layers being comprised of bone permeable material that when implanted would fuse to the vertebrae and form a permanent bond. The middle layer is a polymer with mechanical properties similar to natural spinal discs.

Claims

1. An artificial spinal disc, comprising:

a first annular layer of biocompatible bone permeable material, wherein said first annular layer comprises a first central opening;

a second annular layer of biocompatible bone permeable material, wherein said second annular layer comprises a second central opening;

a core having a first end affixed within said first central opening and having a second end affixed within said second central opening, wherein said core comprises biocompatible material; and

an outer support surrounding and constraining said core, wherein said outer support comprises a tensile strength that is greater than the tensile strength of said core, wherein said outer support limits the compressibility and prevents the outer surface of said outer support from excessive bulging that could put pressure on the spinal cord or nerves,

wherein at least one of said first annular layer and said second annular layer comprises an annular region of bone permeable material, wherein said annular region is designed to bond to the hard cortical bone of a vertebra, wherein said core comprises a material selected from the group consisting of a compressible biocompatible polymer and a biocompatible hydrogel,

wherein said outer support comprises high strength polymers selected from the group consisting of polyurethane and composite material, and

wherein said composite material comprises ultra high molecular weight polyethylene with embedded carbon fibers.

2. The artificial spinal disc of claim 1, wherein at least one of said first annular layer and said second annular layer is planar.

3. The artificial spinal disc of claim 1, wherein at least one of said first annular layer and said second annular layer comprises biocompatible bone permeable material selected from the group consisting of porous titanium, ceramic, glass ceramic, hydroxyapatite and metal coated with polycrystalline alumina (Al₂O₃).

4. The artificial spinal disc of claim 1, wherein said core comprises biocompatible polymer.

5. The artificial spinal disc of claim 4, wherein said biocompatible polymer is selected from the group consisting of polyurethane, polydimethyl siloxane, polyvinyl chloride (PVC), polyethylene and teflon.

6. The artificial spinal disc of claim 1, wherein said core comprises a plurality of materials.

7. The artificial spinal disc of claim 1, wherein said core comprises a central disc of material that diverges from the center of said artificial spinal disc.

8. The artificial spinal disc of claim 7, wherein said central disc of material comprises material selected from the group consisting of silicon rubber, polyurethane/silicon composite and hydrogel.

9. The artificial spinal disc of claim 1, wherein at least one of said first annular layer and said second annular layer comprises a uniform thickness.

10. The artificial spinal disc of claim 1, further comprising bone growth factors applied to at least one of said first annular layer and said second annular layer.

11. The artificial spinal disc of claim 1, wherein said core comprises compressible biocompatible polymer selected from the group consisting of polydimethyl siloxane, polyethylene, polyurethane, silicon rubber compounds and teflon.

12. The artificial spinal disc of claim 1, wherein said core comprises biocompatible hydrogel selected from the group consisting of polyhydroxyethyl methacrylate (PHEMA), polyacrylamides, polyvinyl alcohol, PNVP and hydrogel that uses methacrylic acid as monomers.

13. The artificial spinal disc of claim 1, wherein said core comprises biocompatible hydrogel having a compressibility that can be varied to achieve the desired mechanical properties.

14. The artificial spinal disc of claim 1, wherein the orientation of said embedded carbon fibers is varied to simulate the properties of the natural disc annulus fibrosus.

15. The artificial spinal disc of claim 1, wherein at least one of said first annular layer and said second annular layer is contoured to substantially correspond to a surface of a vertebrae against which at least one of said first annular layer and said second annular layer will be located.

16. The method of claim 1, further comprising surgically shaping the vertebrae above and/or below said first annular layer and said second annular layer to substantially correspond to at least one of said first annular layer and said second annular layer.

17. A method for making an artificial spinal disc, comprising:

forming a first annular layer of biocompatible bone permeable material, wherein said first annular layer comprises a first central opening;

forming a second annular layer of biocompatible bone permeable material, wherein said second annular layer comprises a second central opening;

forming a core of biocompatible material;

affixing a first end of said core within said first central opening;

affixing a second end of said core within said second central opening; and

forming an outer support surrounding and constraining said core, wherein said outer support comprises a tensile strength that is greater than the tensile strength of said core, wherein said outer support limits the compressibility and prevents the outer surface of said outer support from excessive bulging that could put pressure on the spinal cord or nerves,

wherein at least one of said first annular layer and said second annular layer comprises is designed to bond to the hard cortical bone of a vertebra, wherein said core comprises a material selected from the group consisting of a compressible biocompatible polymer and a biocompatible hydrogel,

wherein said outer support comprises high strength polymers selected from the group consisting of polyurethane and composite material, and

wherein said composite material comprises ultra high molecular weight polyethylene with embedded carbon fibers.

18. The method of claim 17, wherein at least one of said first annular layer and said second annular layer is planar.

19. The method of claim 17, wherein at least one of said first annular layer and said second annular layer comprises biocompatible bone permeable material selected from the group consisting of porous titanium, ceramic, glass ceramic, hydroxyapatite and metal coated with polycrystalline alumina (Al₂O₃).

20. The method of claim 17, wherein said core comprises biocompatible polymer.

21. The method of claim 20, wherein said biocompatible polymer is selected from the group consisting of polyurethane, polydimethyl siloxane, polyvinyl chloride (PVC), polyethylene and teflon.

22. The method of claim 17, wherein said core comprises a plurality of materials.

23. The method of claim 17, wherein said core comprises a central disc of material that diverges from the center of said artificial spinal disc.

24. The method of claim 23, wherein said central disc of material comprises material selected from the group consisting of silicon rubber, polyurethane/silicon composite and hydrogel.

25. The method of claim 17, wherein at least one of said first annular layer and said second annular layer comprises a uniform thickness.

26. The method of claim 17, further comprising applying bone growth factors to said at least one of said first annular layer and said second annular layer comprises.

27. The method of claim 17, wherein at least one of said first annular layer and said second annular layer comprises is designed to bond to the hard cortical bone of a vertebra, wherein said core comprises a material selected from the group consisting of a compressible biocompatible polymer and a biocompatible hydrogel.

28. The method of claim 27, wherein said compressible biocompatible polymer is selected from the group consisting of polydimethyl siloxane, polyethylene, polyurethane, silicon rubber compound and teflon.

29. The method of claim 27, wherein said biocompatible hydrogel is selected from a group consisting of polyhydroxyethyl methacrylate (PHEMA) and polyacrylamides, polyvinyl alcohols, PNVP and hydrogels that use methacrylic acid as monomers.

30. The method of claim 27, wherein said biocompatible hydrogel comprises a compressibility that can be varied to achieve the desired mechanical properties.

31. The method of claim 27, further comprising forming an outer support surrounding and constraining said core, wherein said outer support comprises a tensile strength that is greater than the tensile strength of said core, wherein said outer support limits the compressibility and prevents the outer surface of said outer support from excessive bulging that could put pressure on the spinal cord or nerves.

32. The method of claim 31, wherein said outer support comprises high strength polymers selected from the group consisting of polyurethane and composite material.

33. The method of claim 32, wherein said composite material comprises ultra high molecular weight polyethylene with embedded carbon fibers.

34. The method of claim 17, wherein the orientation of said embedded carbon fibers is varied to simulate the properties of the natural disc annulus fibrosus.

35. The method of claim 17, wherein at least one of said first annular layer and said second annular layer is contoured to substantially correspond to a surface of a vertebrae against which said top and bottom layer will be located.

36. The method of claim 35, further comprising obtaining values for contouring at least one of said first annular layer and said second annular layer, wherein said values are obtained with a machine selected from the group consisting of a magnetic resonance imaging machine, a computed tomography machine and an ultrasound imaging machine.