Intervertebral spacer

• US 5,961,554 A
• Filed: 12/31/1996
• Issued: 10/05/1999
• Est. Priority Date: 12/31/1996
• Status: Expired due to Term

• Current Assignee: Albert N. Santilli, Frank S. Janson
• Original Assignee: Albert N. Santilli, Frank S. Janson
• Inventors: Janson, Frank S, Santilli, Albert N.
• Primary Examiner(s): Milano, Michael J.
• Assistant Examiner(s): Nguyen, Tram A.
• Application Number:
  US08/778,023
• Time in Patent Office: 1,008 Days
• Field of Search: 623/17, 623/16, 623/11, 623/18, 606/60, 606/61, 606/76
• US Class Current: 623/17.16
• 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 2/446 having a circular or elliptical cross-section substantially parallel to the axis of the spine, e.g. cylinders or frustocones
• 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 2/447 substantially parallelepipedal, e.g. having a rectangular or trapezoidal cross-section
• CPC Class Codes: A61F 2002/2839 Bone plugs or bone graft dowels
• CPC Class Codes: A61F 2002/30011 differing in porosity
• CPC Class Codes: A61F 2002/30126 oval-O-shaped
• 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 2002/30143 hexagonal
• CPC Class Codes: A61F 2002/30153 rectangular
• CPC Class Codes: A61F 2002/302 toroidal, e.g. rings
• CPC Class Codes: A61F 2002/30224 cylindrical
• CPC Class Codes: A61F 2002/30235 tubular, e.g. sleeves
• CPC Class Codes: A61F 2002/3028 polyhedral different from parallelepipedal and pyramidal
• CPC Class Codes: A61F 2002/30785 parallel
• CPC Class Codes: A61F 2002/30789 perpendicular with respect to each other
• CPC Class Codes: A61F 2002/30879 Ribs
• CPC Class Codes: A61F 2002/30892 parallel
• CPC Class Codes: A61F 2002/30896 : perpendicular with respect to each other
• CPC Class Codes: A61F 2002/30957 : using a positive or a negative model, e.g. moulds
• CPC Class Codes: A61F 2002/30968 : Sintering
• CPC Class Codes: A61F 2230/0008 : elliptical or oval
• 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 2230/0017 : Angular shapes
• CPC Class Codes: A61F 2230/0019 : rectangular
• CPC Class Codes: A61F 2230/0063 : Three-dimensional shapes
• CPC Class Codes: A61F 2230/0065 : toroidal, e.g. ring-shaped, doughnut-shaped
• CPC Class Codes: A61F 2230/0069 : cylindrical
• CPC Class Codes: A61F 2250/0023 : differing in porosity
• 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

A porous intervertebral spacer includes a plurality of fused, generally spherical beads of a biologically inert material, preferably titanium or a titanium alloy. The spacer can include elongate, tortuous strands of titanium wire mesh intermixed with the beads. The spacer also can be made entirely of strands of elongate, fused, tortuous titanium wire mesh. A method of fusing adjacent vertebrae of the spine includes the steps of excising a portion of an intervertebral disc separating adjacent vertebrae and portions of the adjacent vertebrae to define a graft bed, and inserting into she graft bed at least one porous intervertebral spacer according to the invention.

Claims

1. An intervertebral spacer that is porous throughtout consisting essentially of a plurality of fused, generally spherical beads of a biologically inert material selected from the group consisting of substantially pure titanium and a titanium alloy.

2. The spacer of claim 1, wherein the beads occupy a range of generally 45 to 58 percent of the volume of the spacer.

3. The spacer of claim 1, wherein the beads are fused by sintering.

4. The spacer of claim 1, wherein the porosity of the spacer is sufficient to facilitate tissue ingrowth and bony fusion.

5. The spacer of claim 1, wherein the spacer is in the form of a prism having end faces.

6. The spacer of claim 5, wherein the end faces of the prism are selected from the group consisting of a square, a rectangle, a triangle, a hexagon, an octagon, a rhombus, a rhomboid, and a trapezoid.

7. The spacer of claim 1, wherein the spacer is of a generally rectangular shape having opposed, substantially parallel end faces, side faces, and top and bottom faces.

8. The spacer of claim 7, further comprising at least one aperture extending through the spacer and opening through the top and bottom faces.

9. The spacer of claim 8, wherein three apertures are provided, the apertures being spaced equidistantly from each other.

10. The spacer of claim 7, further comprising a second aperture extending through the spacer, the second aperture opening through the end faces.

11. The spacer of claim 7, further comprising ribs formed on the top and bottom faces, the ribs, in cross-section, being generally triangular and extending generally parallel to the end faces.

12. The spacer of claim 1, wherein the spacer is of a generally cylindrical shape having a longitudinal axis and end faces that are parallel to each other.

13. The spacer of claim 12, further comprising at least one aperture extending through the spacer parallel to the end faces.

14. The spacer of claim 13, wherein three apertures are provided, the apertures being spaced equidistantly from each other.

15. The spacer of claim 12, further comprising a large round aperture extending through the spacer parallel to, and concentric with, the longitudinal access, the large round aperture defining a wall thickness of the spacer.

16. The spacer of claim 15, wherein the wall thickness of the spacer is approximately 3 mm.

17. The spacer of claim 15, further comprising at least one aperture extending through the spacer parallel to the end faces.

18. The spacer of claim 16, wherein three apertures are provided, the apertures being spaced equidistantly from each other.

19. The spacer of claim 1, wherein the spacer is of a combined rectangular-cylindrical shape, with opposed, flat end faces that are parallel to each other, opposed, flat side faces that are parallel to each other, and opposed, rounded top and bottom faces.

20. The spacer of claim 19, further comprising at least one aperture extending through the spacer and opening through the top and bottom faces.

21. The spacer of claim 20, wherein three apertures are provided, the apertures being spaced equidistantly from each other.

22. The spacer of claim 19, further comprising a second aperture extending through the spacer, the second aperture opening through the end faces.

23. The spacer of claim 19, further comprising ribs formed on the top and bottom faces, the ribs, in cross-section, being generally triangular and extending generally parallel to the end faces.

24. The spacer of claim 1, wherein the spacer is in the form of a plate having flat, generally parallel upper and lower faces.

25. The spacer of claim 24, wherein the spacer, when viewed from above, is generally C-shaped.

26. The spacer of claim 24, wherein the spacer, when viewed from above, is elliptical with an elliptical opening at its center.

27. The spacer of claim 24, wherein the spacer, when viewed from above, is kidney-shaped.

28. The spacer of claim 24, further comprising ribs formed on the upper and lower faces.

29. The spacer of claim 28, wherein the ribs, in cross-section, are generally triangular.

30. A method of fusing adjacent vertebrae of the spine comprising the steps of:

excising a portion of an intervertebral disc separating adjacent vertebra and portions of the adjacent vertebrae to define a graft bed, and

inserting into the graft bed at least one porous intervertebral spacer that is porous throughtout consisting essentially of a plurality of fused, generally spherical beads of a biologically inert material selected from the group consisting of substantially pure titanium and a titanium alloy.

31. The method of claim 30, wherein the beads occupy a range of generally 45 to 58 percent of the volume of the spacer.

32. The method of claim 30, wherein the beads are fused by sintering.

33. The method of claim 30, wherein the graft bed is formed by an excision from the posterior of the spine.

34. The method of claim 30, wherein the graft bed is formed by an excision from the anterior of the spine.