Apparatus for implantation into bone

• US 6,551,319 B2
• Filed: 03/19/2001
• Issued: 04/22/2003
• Est. Priority Date: 11/08/2000
• Status: Active Grant

• Current Assignee: Cleveland Clinic Foundation
• Original Assignee: Cleveland Clinic Foundation
• Inventors: Lieberman, Isador H.
• Primary Examiner(s): Wilson, John J.
• Application Number:
  US09/812,085
• Publication Number:
  US 20020055738A1
• Time in Patent Office: 764 Days
• Field of Search: 606/61, 606/69, 606/70, 606/71, 606/72, 606/73
• US Class Current: 623/17.11
• CPC Class Codes: A61B 17/70 Spinal positioners or stabilisers ; Bone stabilisers comprising fluid filler in an implant
• CPC Class Codes: A61B 17/7007 Parts of the longitudinal elements, e.g. their ends, being specially adapted to fit around the screw or hook heads
• CPC Class Codes: A61B 17/701 Longitudinal elements with a non-circular, e.g. rectangular, cross-section A61B17/7005, A61B17/7007 take precedence
• CPC Class Codes: A61B 17/7032 Screws or hooks with U-shaped head or back through which longitudinal rods pass
• CPC Class Codes: A61B 17/7055 connected to sacrum, pelvis or skull
• CPC Class Codes: A61B 17/7058 Plates mounted on top of bone anchor heads or shoulders
• CPC Class Codes: A61B 17/8625 Shanks, i.e. parts contacting bone tissue
• CPC Class Codes: A61B 17/8665 Nuts
• CPC Class Codes: A61B 17/869 characterised by an open form, e.g. wire helix
• CPC Class Codes: A61F 2/30744 End caps, e.g. for closing an endoprosthetic cavity
• CPC Class Codes: A61F 2/30767 Special external or bone-contacting surface, e.g. coating for improving bone ingrowth
• CPC Class Codes: A61F 2/30965 Reinforcing the prosthesis by embedding particles or fibres during moulding or dipping
• CPC Class Codes: A61F 2/44 for the spine, e.g. vertebrae, spinal discs
• 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 2/4611 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 2002/30092 using shape memory or superelastic materials, e.g. nitinol
• CPC Class Codes: A61F 2002/30224 : cylindrical
• CPC Class Codes: A61F 2002/30235 : tubular, e.g. sleeves
• CPC Class Codes: A61F 2002/30289 : helically-coiled
• CPC Class Codes: A61F 2002/30324 : differing in thickness
• CPC Class Codes: A61F 2002/30326 : differing in height or in length
• CPC Class Codes: A61F 2002/30383 : made by laterally inserting a protrusion, e.g. a rib into a complementarily-shaped groove
• CPC Class Codes: A61F 2002/30401 : with additional means for preventing or locking said sliding
• CPC Class Codes: A61F 2002/30405 : made by screwing complementary threads machined on the parts themselves
• CPC Class Codes: A61F 2002/30428 : made by inserting a protrusion into a slot
• CPC Class Codes: A61F 2002/30451 : soldered or brazed or welded
• CPC Class Codes: A61F 2002/30507 : using a threaded locking member, e.g. a locking screw or a set screw
• CPC Class Codes: A61F 2002/30568 : Multiple spring systems including two or more helical springs
• CPC Class Codes: A61F 2002/30593 : hollow
• CPC Class Codes: A61F 2002/30604 : modular
• CPC Class Codes: A61F 2002/30738 : Sleeves
• CPC Class Codes: A61F 2002/30769 : madreporic
• CPC Class Codes: A61F 2002/30772 : Apertures or holes, e.g. of circular cross section
• CPC Class Codes: A61F 2002/30841 : Sharp anchoring protrusions for impaction into the bone, e.g. sharp pins, spikes
• CPC Class Codes: A61F 2002/3085 : with a threaded, e.g. self-tapping, bone-engaging surface, e.g. external surface
• CPC Class Codes: A61F 2002/30851 : Multiple threadings
• CPC Class Codes: A61F 2210/0004 : bioabsorbable
• CPC Class Codes: A61F 2210/0014 : using shape memory or superelastic materials, e.g. nitinol
• CPC Class Codes: A61F 2220/0025 : Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
• CPC Class Codes: A61F 2220/0058 : soldered or brazed or welded
• CPC Class Codes: A61F 2230/0069 : cylindrical
• CPC Class Codes: A61F 2230/0091 : helically-coiled or spirally-coiled, i.e. having a 2-D spiral cross-section
• CPC Class Codes: A61F 2250/0036 : differing in thickness
• CPC Class Codes: A61F 2250/0037 : differing in height or in length
• CPC Class Codes: A61F 2310/00017 : Iron- or Fe-based alloys, e.g. stainless steel
• CPC Class Codes: A61F 2310/00023 : Titanium or titanium-based alloys, e.g. Ti-Ni alloys
• CPC Class Codes: Y10S 606/911 : Memory material

Abstract

An apparatus (10) is provided for implantation into a bone (12) in a patient'"'"'s spine or pelvis. The apparatus (10) comprises a platform (24) having a first surface (38) for facing the bone (12). The platform (24) includes structure (32, 34, 36) for connection to a spinal fixation implant (100). The apparatus (10) further comprises helical spikes (50, 52) for embedding into the bone (12) upon rotation of the platform (24). The helical spikes (50, 52) project tangentially from the platform (24) and extend around a longitudinal axis (22). The helical spikes (50, 52) have a tip portion (58) which penetrates into the bone (12) as the platform (24) is rotated. The helical spikes (50, 52), when implanted, have a conical shape that increases in diameter as the helical spikes extend away from the platform (24). The helical spikes (50, 52) may be made from a shape memory alloy.

Claims

1. An apparatus for implanting into a bone in a patient'"'"'s spine or pelvis, said apparatus, when implanted, being resistant to toggling in the bone and to being pulled from the bone, said apparatus comprising:

a platform for engaging a bone in a patient'"'"'s spine or pelvis, said platform having a first surface that is solid and that extends generally transverse to a longitudinal axis of said apparatus, said platform including structure for connection to a spinal fixation implant; and

at least one helical spike for embedding into the bone upon rotation of said platform, said at least one helical spike projecting tangentially from said first surface of said platform and extending around said longitudinal axis, said at least one helical spike having a tip portion at a distal end which penetrates into the bone as said platform is rotated;

said at least one helical spike, when implanted, having a conical shape that increases in diameter as said at least one helical spike extends away from said platform.

2. The apparatus of claim 1, wherein said at least one helical spike has a first condition in which said at least one helical spike has a first maximum diameter and a second condition in which at least a portion of said at least one helical spike expands to a second maximum diameter that is larger than said first maximum diameter.

3. The apparatus of claim 2 wherein said at least one helical spike has a first axial length in said first condition and a second axial length in said second condition, said second axial length being smaller than said first axial length.

4. The apparatus of claim 3 wherein at least a portion of said at least one helical spike is made of a shape memory alloy that is responsive to changes in temperature above and below a predetermined temperature transition range, said at least one helical spike being in said first condition when the temperature of said at least one helical spike is below said predetermined temperature transition range, said at least one helical spike being in said second condition when heated above said predetermined temperature transition range, said at least one helical spike being implanted into the bone in said second condition.

5. The apparatus of claim 4 wherein said at least one helical spike further has a connecting portion at a proximal end connected to said platform and an intermediate portion extending between said connecting,portion and said tip portion, at least one of said intermediate portion and said tip portion being made of said shape memory alloy.

6. The apparatus of claim 5 comprising a pair of helical spikes extending around said longitudinal axis, said proximal ends of said pair of helical spikes being spaced 180°

apart.

7. The apparatus of claim 5 comprising three helical spikes extending around said longitudinal axis, said proximal lends of said three helical spikes being spaced 120°

apart.

8. The apparatus of claim 1 wherein said first surface has a shape that is complimentary to the shape of an outer surface of the bone for engaging the outer surface of the bone.

9. The apparatus of claim 1 wherein said at least one helical spike has a solid cross-section.

10. The apparatus of claim 1 wherein said at least one helical spike has a tubular cross-section.

11. The apparatus of claim 1 wherein a first portion of said at least one helical spike has a solid cross-section and a second portion of said at least one helical spike has a tubular cross-section.

12. An apparatus comprising:

at least one anchor for implantation into a bone, said at least one anchor having a longitudinal axis and, when implanted, being resistant to toggling in the bone and to being pulled from the bone; and

a spinal fixation implant for extending between and connecting a plurality of bones;

said at least one anchor including a platform having a first surface for facing the bone, said first surface being solid and extending generally transverse to said longitudinal axis, said platform further having structure for connection with said spinal fixation implant;

said at least one anchor further including at least two helical spikes for embedding into the bone upon rotation of said platform, said at least two helical spikes projecting tangentially from said first surface on said platform and extending around said longitudinal axis, each of said at least two helical spikes having a tip portion at a distal end which penetrates into the bone as said platform is rotated;

said at least two helical spikes, when implanted, having a conical shape that increases in diameter as said at least two helical spikes extend away from said platform.

13. The apparatus of claim 12 comprises a first anchor for implantation into a first bone and a second anchor for implantation into a second bone spaced from said first bone.

14. The apparatus of claim 13 wherein each of said first and second anchors extends co-linearly along said longitudinal axis, said at least two helical spikes that project from said first surface of said platform of said first anchor extending in a first direction, said at least two helical spikes that project from said first surface of said platform of said second anchor extending in a second direction opposite said first direction.

15. The apparatus of claim 14 wherein said spinal fixation implant comprises a member extending along said longitudinal axis and interconnecting said first and second anchors.

16. An apparatus for implantation into a bone in a patient'"'"'s spine or pelvis, said apparatus, when implanted, being resistant to toggling in the bone and to being pulled from the bone, said apparatus comprising:

a platform for facing a bone in a patient'"'"'s spine or pelvis, said platform having a first surface that is solid and that extends generally transverse to a longitudinal axis of said apparatus, said platform including structure for connection to a spinal fixation implant; and

at least one helical spike for embedding into the bone upon rotation of said platform, said at least one helical spike projecting tangentially from said first surface of said platform and extending around said longitudinal axis, said at least one helical spike having a tip portion at a distal end which penetrates into the bone as said platform is rotated;

said at least one helical spike having a first condition in which said at least one helical spike has a first maximum diameter and a second condition in which at least a portion of said at least one helical spike expands to a second maximum diameter that is larger than said first maximum diameter.

17. The apparatus of claim 16 wherein said at least one helical spike has a first axial length in said first condition land a second axial length in said second condition, said second axial length being smaller than said first axial length.

18. The apparatus of claim 17 wherein at least a portion of said at least one helical spike is made of a shape memory alloy that is responsive to changes in temperature above and below a predetermined temperature transition range, said at least one helical spike being in said first condition when the temperature of said at least one helical spike is below said predetermined temperature transition range, said at least one helical spike being in said second condition when heated above said predetermined temperature transition range, said at least one helical spike being implanted into the bone in said second condition.

19. The apparatus of claim 18 wherein said at least one helical spike, when implanted, has a conical shape that increases in diameter as said at least one helical spike extends away from said platform.

20. The apparatus of claim 19 wherein said at least one helical spike further has a connecting portion at a proximal end connected to said platform and an intermediate portion extending between said connection portion and said tip portion, at least one of said intermediate portion and said tip portion being made of said shape memory alloy.

21. The apparatus of claim 20 comprising a pair of helical spikes extending around said longitudinal axis, said proximal ends of said pair of helical spikes being spaced 180°

apart.

22. The apparatus of claim 20 comprising three helical spikes extending around said longitudinal axis, said proximal ends of said three helical spikes being spaced 120°

apart.

23. The apparatus of claim 16 wherein said first surface has a shape that is complimentary to the shape of an outer surface of the bone for engaging the outer surface of the bone.

24. An apparatus for implanting into a bone in a patient'"'"'s spine or pelvis, said apparatus comprising:

an anchor having a longitudinal axis, said anchor comprising a platform for facing the bone and at least one helical spike for embedding into the bone upon rotation of said platform;

said platform having a first surface that is solid and that extends generally transverse to said longitudinal axis of said anchor, said platform including structure for connection to a spinal fixation implant;

said at least one helical spike projecting tangentially from said first surface of said platform and extending around said longitudinal axis, said at least one helical spike having a tip portion at a distal end which penetrates into the bone as said platform is rotated;

said at least one helical spike having a first condition in which said at least one helical spike has a first maximum diameter and a second condition in which at least a portion of said at least one helical spike expands to a second maximum diameter that is larger than said first maximum diameter;

said anchor, when implanted, being resistant to toggling in the bone and to being pulled from the bone.

25. The apparatus of claim 24 further comprising a tubular sleeve for receiving said anchor, said tubular sleeve having an inside diameter that is approximately equal to said first maximum diameter of said at least one helical spike of said anchor, said anchor being positionable inside said tubular sleeve when in said first condition.

26. The apparatus of claim 25 wherein said tubular sleeve includes internal threads for mating with said at least one helical spike and helping to draw said at least one spike into said tubular sleeve as said platform is rotated.

27. The apparatus of claim 26 wherein said at least one helical spike has a first axial length in said first condition and a second axial length in said second condition, said second axial length being smaller than said first axial length.

28. The apparatus of claim 27 wherein at least a portion of said at least one helical spike is made of a shape memory alloy that is responsive to changes in temperature above and below a predetermined temperature transition range, said at least one helical spike being in said first condition when the temperature of said at least one helical spike is below said predetermined temperature transition range, said at least one helical spike being in said second condition when heated above said predetermined temperature transition range, said at least one helical spike being implanted into the bone in said second condition.

29. The apparatus of claim 28 wherein said at least one helical spike, when implanted, has a conical shape that increases in diameter as said at least one helical spike extends away from said platform.

30. An apparatus for implantation into a bone in a patient'"'"'s spine or pelvis, said apparatus, when implanted, being resistant to toggling in the bone and to being pulled from the bone, said apparatus comprising:

a platform for facing a bone in a patient'"'"'s spine or pelvis, said platform having a first surface that is solid and that extends generally transverse to a longitudinal axis of said apparatus, said platform including structure for connection to a spinal fixation implant; and

at least one helical spike for embedding into the bone upon rotation of said platform, said at least one helical spike projecting tangentially from said first surface of said platform and extending around said longitudinal axis, said at least one helical spike having a tip portion at a distal end which penetrates into the bone as said platform is rotated;

said at least one helical spike having a first condition in which said at least one helical spike has a first axial length and a second condition in which said at least one helical spike has a second axial length that is smaller than said first axial length.

31. The apparatus of claim 30 wherein at least a portion of said at least one helical spike is made of a shape memory alloy that is responsive to changes in temperature above and below a predetermined temperature transition range, said at least one helical spike being in said first condition when the temperature of said at least one helical spike is below said predetermined temperature transition range, said at least one helical spike being in said second condition when heated above said predetermined temperature transition range, said at least one helical spike being implanted into the bone in said second condition.

32. The apparatus of claim 31 wherein said at least one helical spike, when implanted, has a conical shape that increases in diameter as said at least one helical spike extends away from said platform.

33. The apparatus of claim 32 wherein said at least one helical spike has a first maximum diameter in said first condition and at least a portion of said at least one helical spike expands to a second maximum diameter in said second condition, said second maximum diameter being larger than said first maximum diameter.

34. The apparatus of claim 33 wherein said at least one helical spike further has a connecting portion at a proximal end connected to said platform and an intermediate portion extending between said connecting portion and said tip portion, at least one of said intermediate portion and said tip portion being made of said shape memory alloy.

35. The apparatus of claim 34 comprising a pair of helical spikes extending around said longitudinal axis, said proximal ends of said pair of helical spikes being spaced 180°

apart.

36. The apparatus of claim 34 comprising three helical spikes extending around said longitudinal axis, said proximal ends of said three helical spikes being spaced 120°

apart.

37. The apparatus of claim 30 wherein said first surface has a shape that is complimentary to the shape of an outer surface of the bone for engaging the outer surface of the bone.

38. An apparatus for implantation into a bone in a patient'"'"'s spine or pelvis, said apparatus, when implanted, being resistant to toggling in the bone and to being pulled from the bone, said apparatus comprising:

a platform having a first surface for facing a bone in a patient'"'"'s spine or pelvis, said platform having a first surface that is solid and that extends generally transverse to a longitudinal axis of said apparatus, said platform including structure for connection to a spinal fixation implant; and

at least one helical spike for embedding into the bone upon rotation of said platform, said at least one helical spike projecting tangentially from said first surface of said platform and extending around said longitudinal axis, said at least one helical spike having a tip portion at a distal end which penetrates into the bone as said platform is rotated;

at least a portion of said at least one helical spike being made of a shape memory alloy that is responsive to changes in temperature above and below a predetermined temperature transition range, said at least one helical spike having a first shape when the temperature of said at least one helical spike is below said predetermined temperature transition range, said at least one helical spike having a second shape when heated above said predetermined temperature transition range, said at least one helical spike being implanted into the bone in said second shape.

39. The apparatus of claim 38 wherein said at least one helical spike, when implanted, has a conical shape that increases in diameter as said at least one helical spike extends away from said platform.

40. The apparatus of claim 39 wherein said at least one helical spike has a first axial length in said first shape and a second axial length in said second shape, said second axial length being smaller than said first axial length.

41. The apparatus of claim 40 wherein said at least one helical spike has a first maximum diameter in said first shape land at least a portion of said at least one helical spike expands to a second maximum diameter in said second shape, said second maximum diameter being larger than said first maximum diameter.

42. The apparatus of claim 38 wherein said at least one helical spike further has a connecting portion at a proximal end connected to said platform and an intermediate portion extending between said connecting portion and said tip portion, at least one of said intermediate portion and said tip portion being made of said shape memory alloy.

43. The apparatus of claim 42 comprising a pair of helical spikes extending around said longitudinal axis, said proximal ends of said pair of helical spikes being spaced 180°

apart.

44. The apparatus of claim 42 comprising three helical spikes extending around said longitudinal axis, said proximal ends of said three helical spikes being spaced 120°

apart.

45. The apparatus of claim 38 wherein said first surface has a shape that is complimentary to the shape of an outer surface of the bone for engaging the outer surface of the bone.

46. An apparatus for implantation into an adjacent pair of vertebral bodies having first and second surfaces that oppose each other, said apparatus, when implanted, being attached to each of the vertebral bodies and stabilizing the vertebral bodies while the vertebral bodies fuse together, said apparatus comprising:

a platform having a third surface extending generally transverse to a longitudinal axis of said apparatus; and

at least one helical spike for embedding into each of the adjacent pair of vertebral bodies upon rotation of said platform to attach said at least one helical spike to each of the vertebral bodies and thus fasten the vertebral bodies together, said at least one helical spike projecting tangentially from said third surface of said platform and extending around said longitudinal axis, said at least one helical spike having a tip portion at a distal end for penetrating the first and second surfaces and for screwing into the adjacent pair of vertebral bodies as said platform is rotated;

said at least one helical spike at least partially defining an internal cavity for receiving material that promotes fusion of the vertebral bodies;

said at least one helical spike, when implanted, having a conical shape that increases in diameter as said at least one helical spike extends away from said platform.

47. The apparatus of claim 46 wherein said at least one helical spike has a first condition in which said at least one helical spike has a first maximum diameter and a second condition in which at least a portion of said at least one helical spike expands to a second maximum diameter that is larger than said first maximum diameter.

48. The apparatus of claim 47 wherein said at least one helical spike has a first axial length in said first condition and a second axial length in said second condition, said second axial length being smaller than said first axial length.

49. The apparatus of claim 48 wherein at least a portion of said at least one helical spike is made of a shape memory alloy that is responsive to changes in temperature above and below a predetermined temperature transition range, said at least one helical spike being in said first condition when the temperature of said at least one helical spike is below said predetermined temperature transition range, said at least one helical spike being in said second condition when heated above said predetermined temperature transition range, said at least one helical spike being implanted into the bone in said second condition.

50. The apparatus of claim 49 wherein said at least one helical spike further has a connecting portion at a proximal end connected to said platform and an intermediate portion extending between said connecting portion and said tip portion, at least one of said intermediate portion and said tip portion being made of said shape memory alloy.

51. The apparatus of claim 50 comprising a pair of helical spikes extending around said longitudinal axis, said proximal ends of said pair of helical spikes being spaced 180°

apart.

52. The apparatus of claim 50 comprising three helical spikes extending around said longitudinal axis, said proximal ends of said three helical spikes being spaced 120°

apart.

53. The apparatus of claim 46 wherein said at least one helical spike has a solid cross-section.

54. The apparatus of claim 46 wherein said at least one helical spike has a tubular cross-section.

55. The apparatus of claim 46 wherein a first portion of said at least one helical spike has a solid cross-section and a second portion of said at least one helical spike has a tubular cross-section.

56. An apparatus for implantation into an adjacent pair of vertebral bodies having first and second surfaces that oppose each other, said apparatus, when implanted, being attached to each of the vertebral bodies and stabilizing the vertebral bodies while the vertebral bodies fuse together, said apparatus comprising:

a platform having a third surface extending generally transverse to a longitudinal axis of said apparatus; and

at least one helical spike for embedding into each of the adjacent pair of vertebral bodies upon rotation of said platform to attach said at least one helical spike to each of the vertebral bodies and thus fasten the vertebral bodies together, said at least one helical spike projecting tangentially from said third surface of said platform and extending around said longitudinal axis, said at least one helical spike having a tip portion at a distal end for penetrating the first and second surfaces and for screwing into the adjacent pair of vertebral bodies as said platform is rotated;

said at least one helical spike at least partially defining an internal cavity for receiving material that promotes fusion of the vertebral bodies;

said at least one helical spike having a first condition in which said at least one helical spike has a first maximum diameter and a second condition in which at least a portion of said at least one helical spike expands to a second maximum diameter that is larger than said first maximum diameter.

57. The apparatus of claim 56 wherein said at least one helical spike has a first axial length in said first condition and a second axial length in said second condition, said second axial length being smaller than said first axial length.

58. The apparatus of claim 57 wherein at least a portion of said at least one helical spike is made of a shape memory alloy that is responsive to changes in temperature above and below a predetermined temperature transition range, said at least one helical spike being in said first condition when the temperature of said at least one helical spike is below said predetermined temperature transition range, said at least one helical spike being in said second condition when heated above said predetermined temperature transition range, said at least one helical spike being implanted into the bone in said second condition.

59. The apparatus of claim 58 wherein said at least one helical spike, when implanted, has a conical shape that increases in diameter as said at least one helical spike extends away from said platform.

60. The apparatus of claim 59 wherein said at least one helical spike further has a connecting portion at a proximal end connected to said platform and an intermediate portion extending between said connecting portion and said tip portion, at least one of said intermediate portion and said tip portion being made of said shape memory alloy.

61. The apparatus of claim 59 comprising a pair of helical spikes extending around said longitudinal axis, said proximal ends of said pair of helical spikes being spaced 180°

apart.

62. The apparatus of claim 59 comprising three helical spikes extending around said longitudinal axis, said proximal ends of said three helical spikes being spaced 120°

apart.

63. An apparatus for implanting an interbody stabilizer into an adjacent pair of vertebral bodies having first and second surfaces that oppose each other, said apparatus comprising:

an interbody stabilizer having a longitudinal axis, said interbody stabilizer comprising a platform and at least one helical spike for embedding into each of the vertebral bodies upon rotation of said platform to attach said at least one helical spike to each of the vertebral bodies and thus fasten the vertebral bodies together;

a platform having a third surface extending generally transverse to said longitudinal axis;

said at least one helical spike projecting tangentially from said third surface of said platform and extending around said longitudinal axis, said at least one helical spike having a tip portion at a distal end for penetrating the first and second surfaces and for screwing into the adjacent pair of vertebral bodies as said platform is rotated;

said at least one helical spike at least partially defining an internal cavity for receiving material that promotes fusion of the vertebral bodies;

said at least one helical spike having a first condition in which said at least one helical spike has a first maximum diameter and a second condition in which at least a portion of said at least one helical spike expands to a second maximum diameter that is larger than said first maximum diameter;

said interbody stabilizer, when implanted, being attached to each of the vertebral bodies and stabilizing the vertebral bodies while the vertebral bodies fuse together.

64. The apparatus of claim 63 further comprising a tubular sleeve for receiving said interbody stabilizer, said tubular sleeve having an inside diameter that is approximately equal to said first maximum diameter of said at least one helical spike of said interbody stabilizer, said interbody stabilizer being positionable inside said tubular sleeve when in said first condition.

65. The apparatus of claim 64 wherein said tubular sleeve includes internal threads for mating with said at least one helical spike and helping to draw said at least one spike into said tubular sleeve as said platform is rotated.

66. The apparatus of claim 65 wherein said at least one helical spike has a first axial length in said first condition and a second axial length in said second condition, said second axial length being smaller than said first axial length.

67. The apparatus of claim 66 wherein at least a portion of said at least one helical spike is made of a shape memory alloy that is responsive to changes in temperature above and below a predetermined temperature transition range, said at least one helical spike being in said first condition when the temperature of said at least one helical spike is below said predetermined temperature transition range, said at least one helical spike being in said second condition when heated above said predetermined temperature transition range, said at least one helical spike being implanted into the bone in said second condition.

68. The apparatus of claim 67 wherein said at least one helical spike, when implanted, has a conical shape that increases in diameter as said at least one helical spike extends away from said platform.

69. An apparatus for implantation into an adjacent pair of vertebral bodies having first and second surfaces that oppose each other, said apparatus, when implanted, being attached to each of the vertebral bodies and stabilizing the vertebral bodies while the vertebral bodies fuse together, said apparatus comprising:

a platform having a third surface extending generally transverse to a longitudinal axis of said apparatus; and

at least one helical spike for embedding into each of the adjacent pair of vertebral bodies upon rotation of said platform to attach said at least one helical spike to each of the vertebral bodies and thus fasten the vertebral bodies together, said at least one helical spike projecting tangentially from said third surface of said platform and extending around said longitudinal axis, said at least one helical spike having a tip portion at a distal end for penetrating the first and second surfaces and for screwing into the adjacent pair of vertebral bodies as said platform is rotated;

said at least one helical spike at least partially defining an internal cavity for receiving material that promotes fusion of the vertebral bodies;

said at least one helical spike having a first condition in which said at least one helical spike has a first axial length and a second condition in which said at least one helical spike has a second axial length that is smaller than said first axial length.

70. The apparatus of claim 69 wherein at least a portion of said at least one helical spike is made of a shape memory alloy that is responsive to changes in temperature above and below a predetermined temperature transition range, said at least one helical spike being in said first condition when the temperature of said at least one helical spike is below said predetermined temperature transition range, said at least one helical spike being in said second condition when heated above said predetermined temperature transition range, said at least one helical spike being implanted into the bone in said second condition.

71. The apparatus of claim 70 wherein said at least one helical spike, when implanted, has a conical shape that increases in diameter as said at least one helical spike extends away from said platform.

72. The apparatus of claim 71 wherein said at least one helical spike has a first maximum diameter in said first condition and at least a portion of said at least one helical spike expands to a second maximum diameter in said second condition, said second maximum diameter being larger than said first maximum diameter.

73. The apparatus of claim 72 wherein said at least one helical spike further has a connecting portion at a proximal end connected to said platform and an intermediate portion extending between said connecting portion and said tip portion, at least one of said intermediate portion and said tip portion being made of said shape memory alloy.

74. The apparatus of claim 73 comprising a pair of helical spikes extending around said longitudinal axis, said proximal ends of said pair of helical spikes being spaced 180°

apart.

75. The apparatus of claim 73 comprising three helical spikes extending around said longitudinal axis, said proximal ends of said three helical spikes being spaced 120°

apart.

76. An apparatus for implantation into an adjacent pair of vertebral bodies having first and second surfaces that oppose each other, said apparatus, when implanted, being attached to each of the vertebral bodies and stabilizing the vertebral bodies while the vertebral bodies fuse together, said apparatus comprising:

a platform having a third surface extending generally transverse to a longitudinal axis of said apparatus; and

at least one helical spike for embedding into each of the adjacent pair of vertebral bodies upon rotation of said platform to attach said at least one helical spike to each of the vertebral bodies and thus fasten the vertebral bodies together, said at least one helical spike projecting tangentially from said third surface of said platform and extending around said longitudinal axis, said at least one helical spike having a tip portion at a distal end for penetrating the first and second surfaces and for screwing into the adjacent pair of vertebral bodies as said platform is rotated;

said at least one helical spike at least partially defining an internal cavity for receiving material that promotes fusion of the vertebral bodies;

at least a portion of said at least one helical spike being made of a shape memory alloy that is responsive to changes in temperature above and below a predetermined temperature transition range, said at least one helical spike having a first shape when the temperature of said at least one helical spike is below said predetermined temperature transition range, said at least one helical spike having a second shape when heated above said predetermined temperature transition range, said at least one helical spike being implanted into the bone in said second shape.

77. The apparatus of claim 76 wherein said at least one helical spike, when implanted, has a conical shape that increases in diameter as said at least one helical spike. extends away from said platform.

78. The apparatus of claim 77 wherein said at least one helical spike has a first axial length in said first shape and a second axial length in said second shape, said second axial length being smaller than said first axial length.

79. The apparatus of claim 78 wherein said at least one helical spike has a first maximum diameter in said first shape and at least a portion of said at least one helical spike expands to a second maximum diameter in said second shape, said second maximum diameter being larger than said first maximum diameter.

80. The apparatus of claim 79 wherein said at least one helical spike further has a connecting portion at a proximal end connected to said platform and an intermediate portion extending between said connecting portion and said tip portion, at least one of said intermediate portion and said tip portion being made of said shape memory alloy.

81. The apparatus of claim 80 comprising a pair of helical spikes extending around said longitudinal axis, said proximal ends of said pair of helical spikes being spaced 180°

apart.

82. The apparatus of claim 80 comprising three helical spikes extending around said longitudinal axis, said proximal ends of said three helical spikes being spaced 120°

apart.