Polymer filled spinal fusion cage

• US 6,332,894 B1
• Filed: 03/07/2000
• Issued: 12/25/2001
• Est. Priority Date: 03/07/2000
• Status: Expired due to Term

• Current Assignee: Zimmer Technology Incorporated (Zimmer Biomet Holdings, Inc.)
• Original Assignee: Zimmer Incorporated (Zimmer Biomet Holdings, Inc.)
• Inventors: Stalcup, Gregory C, Lozier, Antony J.
• Primary Examiner(s): Hirsch, Paul J.
• Application Number:
  US09/520,893
• Time in Patent Office: 658 Days
• Field of Search: 623/17.12, 623/23.58, 623/23.63, 623/17.11
• US Class Current: 623/17.11
• CPC Class Codes: A61B 17/3211 Surgical scalpels, knives; Accessories therefor
• CPC Class Codes: A61B 17/7095 the filler comprising unlinked macroscopic particles
• CPC Class Codes: A61B 17/7097 Stabilisers comprising fluid filler in an implant, e.g. balloon; devices for inserting or filling such implants disc prostheses made of inflatable chambers or pockets filled with fluid A61F2/441; replacing the nucleus pulposus A61F2002/444
• CPC Class Codes: A61B 17/7098 wherein the implant is permeable or has openings, e.g. fenestrated screw hollow surgical screws A61B17/864
• CPC Class Codes: A61F 2/30744 End caps, e.g. for closing an endoprosthetic cavity
• 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 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 2/4465 having a circular or kidney shaped cross-section substantially perpendicular to the axis of the spine
• CPC Class Codes: A61F 2/4601 for introducing bone substitute, for implanting bone graft implants or for compacting them in the bone cavity
• 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 2002/30062 (bio)absorbable, biodegradable, bioerodable, (bio)resorbable, resorptive
• CPC Class Codes: A61F 2002/30133 kidney-shaped or bean-shaped
• CPC Class Codes: A61F 2002/302 toroidal, e.g. rings
• CPC Class Codes: A61F 2002/30583 filled with hardenable fluid, e.g. curable in-situ
• CPC Class Codes: A61F 2002/30593 hollow
• CPC Class Codes: A61F 2002/4627 with linear motion along or rotating motion about the instrument axis or the implantation direction, e.g. telescopic, along a guiding rod, screwing inside the instrument
• CPC Class Codes: A61F 2002/4635 using minimally invasive surgery
• CPC Class Codes: A61F 2002/465 using heating means
• CPC Class Codes: A61F 2210/0004 : bioabsorbable
• CPC Class Codes: A61F 2210/0085 : hardenable in situ, e.g. epoxy resins
• CPC Class Codes: A61F 2230/0015 : Kidney-shaped, e.g. bean-shaped
• CPC Class Codes: A61F 2230/0065 : toroidal, e.g. ring-shaped, doughnut-shaped
• CPC Class Codes: A61F 2310/00353 : Bone cement, e.g. polymethylmethacrylate or PMMA
• CPC Class Codes: A61L 2430/38 : for reconstruction of the spine, vertebrae or intervertebral discs
• CPC Class Codes: A61L 27/14 : Macromolecular materials
• CPC Class Codes: A61L 27/16 : obtained by reactions only involving carbon-to-carbon unsaturated bonds
• CPC Class Codes: C08L 33/12 : Homopolymers or copolymers of methyl methacrylate

Abstract

An orthopaedic implant for implanting between adjacent vertebrae and a spine, includes a generally annular bag; and a hardened polymer with the bag. The method of fusing adjacent vertebrae in a spine includes the steps of forming an access hole in an annulus of a disc between the adjacent vertebrae; removing the nucleus within the disc to form a cavity surrounded by the annulus; placing a generally annular bag within the cavity; filling the bag with a polymer; injecting bone particles into the cavity surrounded by the annular bag; and hardening the polymer.

Claims

1. A method of fusing adjacent vertebrae in a spine, comprising the steps of:

forming an access hole in an annulus of a disc between the adjacent vertebrae;

removing the nucleus within the disc to form a cavity surrounded by said annulus;

placing a generally annular bag within said cavity;

filling said bag with a polymer;

injecting bone particles into a portion of said cavity surrounded by said annular bag; and

hardening said polymer.

2. The method of claim 1, wherein said filling step comprises filling said bag with said polymer to a first predetermined amount, and comprising the further step of filling said bag with said polymer to a second predetermined amount, said second filling step occurring after said injecting step.

3. The method of claim 2, wherein said second filling step compresses said bone particles in a radially inward direction into a column, and expands said column in an axial direction.

4. The method of claim 3, wherein said expansion of said bone particles in said axial direction loads said bone particles against an end plate of each respective said adjacent vertebrae.

5. The method of claim 3, wherein said second filling step provides height adjustment of said disc between said adjacent vertebrae.

6. The method of claim 1, wherein said bone particles comprise bone chips.

7. The method of claim 1, wherein said bone particles are suspended within a matrix.

8. The method of claim 1, wherein said forming step comprises forming said access hole in a side of said disc.

9. The method of claim 1, wherein said removing step comprises evacuating said nucleus from said disc.

10. The method of claim 1, wherein said placing step comprises the sub-steps of:

folding said bag;

inserting said folded bag within a pre-load tube;

inserting at least an end of said pre-load tube into said cavity; and

pushing said folded bag from said pre-load tube into said cavity.

11. The method of claim 1, wherein said filling step comprises injecting said polymer under pressure into said bag.

12. The method of claim 11, wherein said bag is expandable under said pressure.

13. The method of claim 1, wherein said polymer comprises a curable polymer.

14. The method of claim 13, wherein said polymer is curable with one of thermal energy, light energy, X-ray energy and a chemical catalyst.

15. The method of claim 14, wherein said hardening step comprises hardening said polymer with a chemical catalyst.

16. The method of claim 1, wherein said bag comprises a porous bag allowing some of said polymer to pass therethrough.

17. An orthopaedic implant for implanting between adjacent vertebrae in a spine, comprising:

a generally annular bag; and

a hardened polymer within said bag.

18. The orthopaedic implant of claim 17, further comprising a fill tube connected with said bag for injecting said polymer into said bag.

19. The orthopaedic implant of claim 17, wherein said polymer comprises a curable polymer.

20. The orthopaedic implant of claim 19, wherein said polymer is curable with one of thermal energy, light energy, X-ray energy and a chemical catalyst.

21. The orthopaedic implant of claim 20, wherein said polymer comprises polymethylmethacrylate.

22. The orthopaedic implant of claim 17, wherein said bag comprises a porous bag allowing some of said polymer to pass therethrough.