Modular interbody fusion implant

• US 6,468,311 B2
• Filed: 01/22/2001
• Issued: 10/22/2002
• Est. Priority Date: 01/22/2001
• Status: Expired due to Fees

• Current Assignee: Warsaw Orthopedic Incorporated (Medtronic Plc)
• Original Assignee: SDGI Holdings Incorporated (Medtronic Plc)
• Inventors: Boyd, Lawrence M., Ray, Eddie F. III, Kozak, Jeffrey
• Primary Examiner(s): Willse, David H.
• Assistant Examiner(s): BARRETT, THOMAS C
• Application Number:
  US09/766,948
• Publication Number:
  US 20020099444A1
• Time in Patent Office: 638 Days
• Field of Search: 623/17.11, 623/17.16
• US Class Current: 623/17.16
• CPC Class Codes: A61F 2/28 Bones joints A61F2/30
• 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 2002/30004 the prosthesis being made from materials having different values of a given property at different locations within the same prosthesis
• CPC Class Codes: A61F 2002/30057 made from both cortical and cancellous adjacent parts
• CPC Class Codes: A61F 2002/30131 horseshoe- or crescent- or C-shaped or U-shaped
• CPC Class Codes: A61F 2002/30133 kidney-shaped or bean-shaped
• CPC Class Codes: A61F 2002/30387 Dovetail connection
• CPC Class Codes: A61F 2002/30448 using adhesives
• CPC Class Codes: A61F 2002/30507 using a threaded locking member, e.g. a locking screw or a set screw
• CPC Class Codes: A61F 2002/30604 modular
• CPC Class Codes: A61F 2002/30772 Apertures or holes, e.g. of circular cross section
• CPC Class Codes: A61F 2002/30828 parallel
• CPC Class Codes: A61F 2002/30831 perpendicular with respect to each other
• CPC Class Codes: A61F 2002/30904 serrated profile, i.e. saw-toothed
• CPC Class Codes: A61F 2002/4485 comprising three or more adjacent spinal implants
• CPC Class Codes: A61F 2220/0025 Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
• CPC Class Codes: A61F 2220/005 using adhesives
• CPC Class Codes: A61F 2230/0013 : Horseshoe-shaped, e.g. crescent-shaped, C-shaped, U-shaped
• CPC Class Codes: A61F 2230/0015 : Kidney-shaped, e.g. bean-shaped
• CPC Class Codes: A61F 2250/0014 : having different values of a given property or geometrical feature, e.g. mechanical property or material property, at different locations within the same prosthesis

Abstract

An interbody fusion device for engagement between vertebrae includes a pair of lateral spacers for spacing the vertebrae, and a connecting member adapted to couple together the lateral spacers when inserted between the vertebrae. The connecting member, individual lateral spacers, or the entire spinal spacer can be made of bone in order to promote fusion of the vertebrae. The modular construction permits use of bone segments otherwise unsuitable due to size or strength in stable fusion devices.

Claims

1. A spinal spacer for engagement between vertebrae, comprising:

a pair of lateral spacers made of bone remnant for spacing the vertebrae, wherein each of said lateral spacers has a medial side, an arcuate lateral side, beveled edges, and a pair of grooved vertebrae engaging surfaces adapted to engage the vertebrae, wherein a portion of said medial side is defined by a medullary canal wall, wherein said medial side has a channel with an angled end face defined therein, and wherein said channel has a dovetail cross-sectional profile; and

a connecting member made of bone, wherein said connecting member has a pair of rails engaged with said channels of said lateral spacers, wherein said rails have a dovetail cross-sectional profile, wherein said connecting member has beveled edges, wherein said connecting member has a pair of grooved vertebrae engaging surfaces, wherein said connecting member has a portion of a medullary canal defined therein, wherein said medullary canal has an opening at both of said grooved vertebrae engaging surfaces, and wherein said connecting member has a central guide bore defined therein.

2. A method of manufacturing a spinal spacer, comprising:

obtaining a first piece of bone having a first medial side with a portion thereof defined by a first medullary canal portion, and a first lateral side;

defining a first coupling structure on said first medial side;

obtaining a second piece of bone having a second medial side with a portion thereof defined by a second medullary canal portion, and a second lateral side;

defining a second coupling structure on said second medial side;

obtaining a third piece of bone with at least a portion of a medullary canal defined therein; and

defining a pair of rails in the third piece of bone such that the pair of rails are adapted to engage the first and second coupling structures.

3. The method of claim 2, further comprising:

shaping a first pair of grooved vertebrae engaging surfaces on the first piece of bone;

shaping a second pair of grooved vertebrae engaging surfaces on the second piece of bone; and

shaping a third pair of grooved vertebrae engaging surfaces on the third piece of bone.

4. The method of claim 3, further comprising:

beveling the first lateral side of the first piece of bone; and

beveling the second lateral side of the second piece of bone.

5. The method of claim 2, wherein:

the first medial side has a posterior end and an anterior end;

the first medullary canal portion defines a concave surface between the posterior end and the anterior end; and

said defining the first coupling structure includes forming a channel that is interrupted by the concave surface between the posterior end and the anterior end.

6. A spinal implant for engagement between vertebrae, comprising:

a pair of lateral spacers formed of bone for spacing the vertebrae, said lateral spacers each having upper and lower vertebrae engaging surfaces adapted to engage the vertebrae, said lateral spacers each having opposite lateral and medial sides disposed between said upper and lower vertebrae engaging surfaces, wherein at least a portion of one of said medial sides is defined by at least a portion of a medullary canal wall; and

a connecting member separate constructed and arranged to couple together said lateral spacers at said medial sides when inserted between the vertebrae.

7. The implant of claim 6, wherein said connecting member has a pair of rails, and wherein each of said medial sides of said lateral spacers has a channel defined therein to engage said rails.

8. The implant of claim 7, wherein:

said lateral spacers each has a posterior end and an anterior end; and

said anterior end defines an anterior end wall.

9. The implant of claim 8, wherein:

said medullary canal wall defines a concave medial surface; and

said channel is interrupted by said concave medial surface and resumes at said posterior end.

10. The implant of claim 9, wherein said channel includes an angular end face at said posterior end to act as a stopper for said rails of said connecting member.

11. The implant of claim 10, wherein said lateral sides each has a convex arcuate shape to coincide with an apophysis ring of the vertebrae.

12. The implant of claim 11, wherein:

said lateral spacers have first beveled edges between said lateral sides and said upper vertebrae engaging surfaces; and

said lateral spacers have second beveled edges between said lateral sides and said lower vertebrae engaging surfaces.

13. The implant of claim 12, wherein:

said lateral spacers each has a lateral most height at a maximum point of curvature of said convex arcuate shape;

said lateral spacers each has a maximum height at a juncture between said medial sides and said anterior end wall; and

said lateral spacers increase in height from said lateral most height to said maximum height.

14. The implant of claim 13, wherein said lateral spacers increase in height in a non-linear fashion from said lateral most height to said maximum height.

15. The implant of claim 14, wherein said connecting member is made of bone with a second medullary canal defining a central opening to receive bone graft material.

16. The implant of claim 15, wherein said central connecting member defines a guide bore adapted to engage an insertion tool, said guide bore being in communication with said central opening to act as an injection port after insertion.

17. The implant of claim 16, further comprising:

a second connecting member made of bone, wherein said second connecting member is adapted to couple together said lateral spacers when inserted between the vertebrae.

18. The implant of claim 17, wherein said upper and lower vertebrae engaging surfaces are grooved.

19. The implant of claim 18, wherein said lateral spacers are made from remnants of bone discarded during fabrication of other implants.

20. The implant of claim 19, wherein said channel has a dovetail cross section.

21. The spinal implant of claim 20, wherein both of said lateral spacers have said medial sides defined by said medullary canal wall.

22. The implant of claim 6, wherein said lateral spacers are made from bone remnants from fabrication of other implants.

23. The spinal implant of claim 6, wherein both of said lateral spacers have said medial sides defined by said medullary canal wall.

24. The implant of claim 23, wherein said connecting member has a pair of rails, and wherein each of said medial sides of said lateral spacers has a channel defined therein to engage said rails.

25. The implant of claim 24, wherein:

said lateral spacers each has a posterior end and an anterior end;

said medullary canal wall defines a concave medial surface; and

said channel is interrupted by said concave medial surface and resumes at said posterior end.

26. The implant of claim 25, wherein said channel includes an angular end face at said posterior end to act as a stopper for said rails of said connecting member.

27. The implant of claim 23, wherein:

said medullary canal wall defines concave medial surfaces in said medial sides; and

said lateral sides each has a convex arcuate shape to coincide with an apophysis ring of the vertebrae.

28. The implant of claim 6, wherein:

said lateral spacers each has a posterior end and an anterior end;

said medial sides each defines concave medial surface; and

said lateral sides each defines a convex arcuate shape to coincide with an apophysis ring of the vertebrae.

29. The implant of claim 28, wherein:

said lateral spacers each has a lateral most height at a maximum point of curvature of said convex arcuate shape;

said lateral spacers each has a maximum height at a juncture between said medial sides and said anterior end wall of each of said lateral spacers; and

said lateral spacers increase in height from said lateral most height to said maximum height.

30. The implant of claim 29, wherein said lateral spacers increase in height in a non-linear fashion from said lateral most height to said maximum height.

31. The implant of claim 6, wherein said connecting member is made of bone with a second medullary canal defining a central opening to receive bone graft material.

32. The implant of claim 6, further comprising:

a second connecting member made of bone, wherein said second connecting member is adapted to couple together said lateral spacers when inserted between the vertebrae.

33. The implant of claim 6, wherein said upper and lower vertebrae engaging surfaces are grooved.

34. The implant of claim 6, wherein:

said connecting member defines a pair of channels; and

said lateral spacers define rails at said medial sides adapted to engage said channels.

35. The implant of claim 6, further comprising screws to secure said lateral spacers to said connecting member.

36. A spinal implant for engagement between vertebrae, comprising:

a connecting member made of bone remnant with a medullary canal defining a central opening to receive bone graft material; and

a pair of lateral spacers each having upper and lower vertebrae engaging surfaces adapted to engage the vertebrae, said lateral spacers each having opposite lateral and medial sides disposed between said upper and lower vertebrae engaging surfaces, wherein said medial sides are adapted to connect to said connecting member, said medial sides each defines concave medial surface, and said lateral sides each defines a convex arcuate shape to coincide with an apophysis ring of the vertebrae.

37. The implant of claim 36, wherein:

said lateral spacers are made of bone remnant; and

said concave medial surface of both of said lateral spacers includes at least a portion of a second medullary canal.

38. The implant of claim 36, wherein said connecting member has a pair of rails, and wherein each of said medial sides of said lateral spacers has a channel defined therein to engage said rails.

39. The implant of claim 36, wherein said bone remnant used to make said connecting member lacks sufficient size to contact the apophysis ring of the vertebrae.