Expandable push-in arcuate interbody spinal fusion implant with cylindrical configuration during insertion

• US 7,008,453 B1
• Filed: 07/07/2000
• Issued: 03/07/2006
• Est. Priority Date: 02/04/2000
• Status: Expired due to Term

• Current Assignee: Warsaw Orthopedic Incorporated (Medtronic Plc)
• Original Assignee: SDGI Holdings Incorporated (Medtronic Plc)
• Inventors: Michelson, Gary Karlin
• Primary Examiner(s): Wilson, John J
• Application Number:
  US09/612,188
• Time in Patent Office: 2,069 Days
• Field of Search: 623/17.11, 623/17.16, 623/17.12, 623/17.13, 623/17.14, 623/17.15, 623/17.4, 606/61
• US Class Current: 623/17.16
• CPC Class Codes: A61B 17/8052 immobilised relative to screws by interlocking form of the heads and plate holes, e.g. conical or threaded
• CPC Class Codes: A61B 17/86 Pins or screws or threaded wires; nuts therefor A61B17/72 take precedence
• CPC Class Codes: A61F 2/28 Bones joints A61F2/30
• CPC Class Codes: A61F 2/30744 End caps, e.g. for closing an endoprosthetic cavity
• 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 2/4465 having a circular or kidney shaped cross-section substantially perpendicular to the axis of the spine
• CPC Class Codes: A61F 2/4611 of spinal prostheses
• CPC Class Codes: A61F 2002/2817 Bone stimulation by chemical reactions or by osteogenic or biological products for enhancing ossification, e.g. by bone morphogenetic or morphogenic proteins [BMP] or by transforming growth factors [TGF]
• 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 2002/30143 hexagonal
• CPC Class Codes: A61F 2002/30187 D-shaped or half-disc-shaped
• CPC Class Codes: A61F 2002/30261 parallelepipedal
• CPC Class Codes: A61F 2002/30331 made by longitudinally pushing a protrusion into a complementarily-shaped recess, e.g. held by friction fit
• CPC Class Codes: A61F 2002/30362 with possibility of relative movement between the protrusion and the recess
• CPC Class Codes: A61F 2002/30392 Rotation
• CPC Class Codes: A61F 2002/30405 made by screwing complementary threads machined on the parts themselves
• CPC Class Codes: A61F 2002/305 Snap connection
• CPC Class Codes: A61F 2002/30517 : using a locking plate
• CPC Class Codes: A61F 2002/30538 : for adjusting angular orientation
• CPC Class Codes: A61F 2002/30556 : for adjusting thickness
• CPC Class Codes: A61F 2002/30593 : hollow
• CPC Class Codes: A61F 2002/30616 : Sets comprising a plurality of prosthetic parts of different sizes or orientations
• CPC Class Codes: A61F 2002/30624 : Hinged joint, e.g. with transverse axle restricting the movement
• CPC Class Codes: A61F 2002/30632 : with rotation-limiting stops, e.g. projections or recesses
• CPC Class Codes: A61F 2002/30774 : internally-threaded
• CPC Class Codes: A61F 2002/30777 : Oblong apertures
• CPC Class Codes: A61F 2002/30779 : arcuate
• CPC Class Codes: A61F 2002/30785 : parallel
• CPC Class Codes: A61F 2002/30787 : inclined obliquely with respect to each other
• CPC Class Codes: A61F 2002/30789 : perpendicular with respect to each other
• CPC Class Codes: A61F 2002/3079 : Stepped or enlarged apertures, e.g. having discrete diameter changes
• CPC Class Codes: A61F 2002/30836 : knurled
• CPC Class Codes: A61F 2002/30841 : Sharp anchoring protrusions for impaction into the bone, e.g. sharp pins, spikes
• CPC Class Codes: A61F 2002/30891 : Plurality of protrusions
• CPC Class Codes: A61F 2002/30904 : serrated profile, i.e. saw-toothed
• CPC Class Codes: A61F 2002/30975 : made of two halves
• CPC Class Codes: A61F 2002/448 : comprising multiple adjacent spinal implants within the same intervertebral space or within the same vertebra, e.g. comprising two 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 2220/0033 : made by longitudinally pushing a protrusion into a complementary-shaped recess, e.g. held by friction fit
• CPC Class Codes: A61F 2230/0017 : Angular shapes
• CPC Class Codes: A61F 2230/0034 : D-shaped
• CPC Class Codes: A61F 2230/0082 : parallelepipedal
• CPC Class Codes: A61F 2250/0006 : for adjusting angular orientation
• CPC Class Codes: A61F 2250/0009 : for adjusting thickness
• 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: A61F 2310/00071 : Nickel or Ni-based alloys
• CPC Class Codes: A61F 2310/00179 : Ceramics or ceramic-like structures
• CPC Class Codes: A61F 2310/00293 : containing a phosphorus-containing compound, e.g. apatite
• CPC Class Codes: A61F 2310/00359 : Bone or bony tissue
• CPC Class Codes: A61F 2310/00407 : Coating made of titanium or of Ti-based alloys
• CPC Class Codes: A61F 2310/00796 : Coating or prosthesis-covering structure made of a phosphorus-containing compound, e.g. hydroxy(l)apatite

Abstract

An at least in part cylindrical push-in interbody spinal fusion implant having an expandable height.

Claims

1. A push-in interbody spinal fusion implant for at least in part linear insertion across the surgically corrected height of a disc space between two adjacent vertebral bodies of a spine, said implant comprising:

an upper member having a portion being at least in part arcuate adapted for placement toward and at least in part within one of them adjacent vertebral bodies, said upper member having at least one opening adapted to communicate with one of the adjacent vertebral bodies, said upper member having a proximal end and a distal end;

a lower member having a portion being at least in part arcuate adapted for placement toward and at least in part within the other of the adjacent vertebral bodies, said lower member having at least one opening adapted to communicate with the other of the adjacent vertebral bodies, said openings of said upper and lower members being in communication with one another and adapted for permitting for the growth of bone from adjacent vertebral body to adjacent vertebral body through said implant and being sufficiently sized and located to allow for interbody spinal fusion through said implant, said lower member having a proximal end and a distal end corresponding to said proximal end and said distal end of said upper member, respectively, and a length between said proximal and distal ends, said upper and lower members articulating therebetween adjacent one of said proximal ends and said distal ends of said upper and lower members and allowing for expansion of the height of said implant, said upper and lower members having a first position relative to one another allowing for a collapsed implant height and a second position relative to one another allowing for an increased height said arcuate portions of said upper and lower members in the first position being parallel to one another over a substantial portion of the length of said implant and forming at least a portion of a cylinder along the length of said implant;

at least a portion of a bone-engaging projection is adapted for linear insertion formed on the exterior of each of said opposed arcuate portions of said upper and lower members for penetrably engaging the adjacent vertebral bodies and to facilitate securing said implant into the spine;

at least one blocker adapted to cooperatively engage and hold at least a portion of said upper and lower members apart so as to maintain the increased height of said implant and resist the collapse of said implant to the collapsed implant height when said implant is in a final deployed position, said blocker being configured to rotate in a plane generally perpendicular to a longitudinal axis of said implant and at a predetermined location along the length of said implant, said blocker remaining at the predetermined location in transitioning said implant from said first position to said second position; and

a hollow defined between said upper and lower members in communication with said openings in each of said upper and lower members, said hollow being adapted to receive fusion-promoting substances, said hollow having a width that is substantially unobstructed by any mechanism for moving said blocker.

2. The push-in implant of claim 1, further comprising a second hollow between said upper and lower members located between said blocker and said end of said implant proximate said blocker.

3. The push-in implant of claim 1, wherein said implant has a constant width in both the collapsed height and the increased height.

4. The push-in implant of claim 1, wherein said blocker is located at least in part between said upper and lower members.

5. The push-in implant of claim 1, wherein said blocker is located proximate at least one of said ends of said upper and lower members.

6. The push-in implant of claim 1, wherein said blocker is adapted to cooperatively engage a tool used to move said blocker from an initial position to a final position to increase the height of said implant, said tool not being a part of said implant and being removed from said implant after moving said blocker into the final position.

7. The push-in implant of claim 1, wherein said implant has a width and said blocker has a width less than the width of said implant.

8. The push-in implant of claim 1, wherein said implant has side walls and said blocker does not contact said side walls when said implant is in the final deployed position.

9. The push-in implant of claim 1, wherein each of said upper and lower members are adapted to cooperate with and to fixedly locate said blocker.

10. The push-in implant of claim 9, wherein each of said upper and lower members have a track configured to permit said blocker to seat therein.

11. The push-in implant of claim 10, wherein at least one of said tracks and said blocker are adapted to cooperate with each other to center said blocker along the longitudinal axis of said implant.

12. The push-in implant of claim 1, wherein said blocker moves said arcuate portions of said upper and lower members from a parallel orientation to an angled orientation relative to one another.

13. The push-in implant of claim 1, further comprising a second blocker located between said upper and lower members for holding at least a portion of the upper and lower members apart where said second blocker is located.

14. The push-in implant of claim 1, wherein said blocker is an expander adapted to expand said implant from a first collapsed height to a second expanded height when moved from a first to a second position.

15. The push-in implant of claim 14, wherein said expander is located along the length of said implant.

16. The push-in implant of claim 14, wherein said expander is located proximate said proximal ends of said upper and lower members.

17. The push-in implant of claim 14, wherein said expander is located proximate said distal ends of said upper and lower members.

18. The push-in implant of claim 14, wherein said hollow is substantially unobstructed by said expander extending along a substantial portion of the length of said hollow so as to permit growth of bone from adjacent vertebral body to adjacent vertebral body through said implant.

19. The push-in implant of claim 14, wherein said expander is adapted to cooperatively engage a tool used to move said expander from an initial position to a final position to increase the height of said implant, said tool not being a part of said implant and being removed from said implant after moving said expander into the final position.

20. The push-in implant of claim 14, wherein said expander is adapted to cooperatively engage a tool that rotates about an axis parallel to the longitudinal axis of said implant to rotate said expander to increase the height of said implant.

21. The push-in implant of claim 20, wherein said expander rotates in a plane perpendicular to the longitudinal axis of said implant to increase the height of said implant.

22. The push-in implant of claim 14, wherein said expander moves said arcuate portions of said upper and lower members from a parallel orientation to an angled orientation relative to one another.

23. The pushpin implant of claim 14, wherein each of said upper and lower members are adapted to cooperate with said expander.

24. The push-in implant of claim 23, wherein each of said upper and lower members have a track configured to permit said expander to rotate therein.

25. The push-in implant of claim 24, wherein said track of said upper member and said track of said lower member are in the same plane.

26. The push-in implant of claim 24, wherein said track of said upper member and said track of said lower member are parallel to one another.

27. The push-in implant of claim 24, where said track of said upper member and said track of said lower member are in a plane perpendicular to the longitudinal axis of said implant.

28. The push-in implant of claim 23, wherein said upper and lower members are adapted to cooperate with said expander so as to center said expander within a cross section of the upper and lower members.

29. The push-in implant of claim 14, wherein said upper and lower members structurally cooperate with said expander so as to keep said expander located within said implant.

30. The push-in implant of claim 14, wherein said expander has a first height corresponding to the height of said expander when said implant is initially inserted into the spine said expander-having a second height corresponding to the height of said expander when said expander is moved into a final deployed position to increase the height of said implant, said second height being greater than said first height.

31. The push-in implant of claim 30, wherein the difference between said first height and said second height of said expander approximates the difference in height of said implant between said first position and said second position as measured proximate the location of said expander.

32. The push-in implant of claim 14, wherein said expander has an upper surface, a lower surface, and side surfaces as defined when said expander is positioned to increase the height of said implant, said side surfaces intersecting said upper and said lower surfaces at two diametrically opposed junctions.

33. The push-in implant of claim 32, wherein said two diametrically opposed junctions are a pair of diametrically opposed corners and a pair of diametrically opposed arcs.

34. The push-in implant of claim 33, wherein said two diametrically opposed arcs are each of the same radius.

35. The push-in implant of claim 34, wherein the distance across said two diametrically opposed arcs generally approximates the distance between said upper and lower surfaces of said expander.

36. The push-in implant of claim 33, wherein said two diametrically opposed corners form a 90-degree angle.

37. The push-in implant of claim 32, wherein each of said upper and lower surfaces lie generally in a plane.

38. The push-in implant of claim 32, wherein said upper and lower surfaces are generally parallel to one another.

39. The push-in implant of claim 32, wherein said side surfaces and said upper and lower surfaces are oriented to substantially form a parallelogram.

40. The push-in implant of claim 14, wherein said expander has a depth dimension less than that of said first and second height of said expander.

41. The push-in implant of claim 40, wherein said expander has a fixed shape during movement from an initial insertion position to a final deployed position within said implant.

42. The push-in implant of claim 40, wherein the depth dimension of said expander is less than one-half of said first and second height of said expander.

43. The push-in implant of claim 14, further comprising a second expander located between said upper and lower members for moving at least a portion of the upper and lower members away from one another to increase the maximum height of said implant where said second expander is located.

44. The push-in implant of claim 43, wherein said second expander rotates to increase the height of said implant.

45. The push-in implant of claim 43, wherein said second expander is located proximate an end of said implant opposite said expander.

46. The push-in implant of claim 45, wherein said hollow is substantially unobstructed by said second expander extending along a substantial portion of the length of said hollow so as to permit growth of bone from adjacent vertebral body to adjacent vertebral body through said implant.

47. The push-in implant of claim 45, wherein said second expander remains in the same location along the longitudinal axis of the implant when rotated.

48. The push-in implant of claim 43, wherein said second expander rotates in a plane perpendicular to the longitudinal axis of said implant to increase the height of said implant.

49. The push-in implant of claim 43, wherein said second expander is located proximate one of the proximal end and the distal end of said upper and lower members.

50. The push-in implant of claim 49, wherein said hollow is unobstructed by said second expander extending along a substantial portion of the length of said hollow to permit growth of bone from adjacent vertebral body to adjacent vertebral body through said implant.

51. The push-in implant of claim 49, further comprising a second hollow between said upper and lower member located between said second expander and said end of said implant proximate said second expander.

52. The push-in implant of claim 43, wherein each of said upper and lower members have a track within which said second expander rotates.

53. The push-in implant of claim 52, wherein said track is configured to permit said second expander to rotate therein and then to move from side to side within said track.

54. The push-in implant of claim 43, wherein said second expander has a first height corresponding to the height of said second expander when said implant is initially inserted into the spine, said second expander having a second height corresponding to the height of said second expander when said second expander is moved into a final deployed position to increase the height of said implant, said second height being greater than said first height.

55. The push-in implant of claim 43, wherein said second expander has an upper surface, a lower surface, and side surfaces as defined when said second expander is positioned to increase the height of said implant, and said side surfaces intersecting said upper and said lower surfaces at two diametrically opposed junctions.

56. The push-in implant of claim 55, wherein the difference between said first height and said second height of said second expander approximates the difference in height of said implant between said first position and said second position as measured proximate the location of said second expander.

57. The push-in implant of claim 1, wherein said upper and lower members are configured to cooperate with one another so as to stop said upper and lower members from being moved apart from one another more than a predetermined distance.

58. The push-in implant of claim 1, wherein said upper and lower members have walls contacting one another.

59. The push-in implant of claim 58, wherein said walls are aligned parallel with the longitudinal axis of said implant.

60. The push-in implant of claim 58, wherein said walls are at least in part overlapping.

61. The push-in implant of claim 1, wherein said upper and lower members have a rotational articulation therebetween adjacent one of said proximal end and said distal end of said upper and lower members.

62. The push-in implant of claim 61, wherein said rotational articulation is at one of said proximal end and said distal end of said upper and lower members opposite said blocker.

63. The push-in implant of claim 61, wherein said rotational articulation allows for expansion.

64. The push-in implant of claim 63, wherein said rotational articulation allows for limited expansion.

65. The push-in implant of claim 61, wherein said rotational articulation is formed by said upper and lower members interdigitating so as to cooperatively engage.

66. The push-in implant of claim 65, wherein said rotational articulation is configured such that engagement occurs when said upper and lower members are substantially perpendicular to one another.

67. The push-in implant of claim 66, wherein said rotational articulation is configured to remain engaged within a range of movement of said upper and lower members resulting from positioning said implant in the second position.

68. The push-in implant of claim 1, wherein one of said upper and lower members has an interior wall, which is unexposed, extending therefrom toward the other of said upper and lower members when said implant is in an initial insertion position, and when said implant is in a final position said implant has a shape such that each of said arcuate portions of said upper and lower members are separated by at least a portion of said interior wall, which now has an exposed side.

69. The push-in implant of claim 68, wherein said upper and lower members have side walls for engaging each other.

70. The push-in implant of claim 69, wherein said side walls of said upper and lower members are at least partially overlapping wall.

71. The push-in implant of claim 68, wherein said arcuate portions of said upper and lower members form an angular orientation relative to one another when said implant is in the final position.

72. The push-in implant of claim 68, wherein said arcuate portions of said upper and lower members when said implant is in the initial insertion position form a cylindrical shape.

73. The push-in implant of claim 1, wherein said implant has an interior, at least one of said upper and lower members has a screw hole passing therethrough adapted to receive a screw passing from said interior of said implant into one of the adjacent vertebral bodies.

74. The push-in implant of claim 73, wherein each of said upper and lower members has at least one screw hole passing therethrough adapted to receive a screw passing from said interior of said implant into the adjacent vertebral body in contact with each of said upper and lower members respectively.

75. The push-in implant of claim 73, further comprising at least one screw adapted to pass from said interior of said implant through said screw hole and into the adjacent vertebral body to anchor said implant to the adjacent vertebral body.

76. The push-in implant of claim 1, wherein said implant has a side surface when in a final position that is contoured to cooperate with another implant.

77. The push-in implant of claim 76, wherein said implant and said cooperating other implant have a combined width therebetween less than the combined height of said implant and said cooperating other implant.

78. The push-in implant of claim 1, further comprising a cap for closing one of said proximal end and said distal end of said upper and lower members, said cap having an exterior surface and an interior surface.

79. The push-in implant of claim 78, wherein said interior surface of said cap has spaced slots about its circumference to facilitate a snap fit of said cap into said implant.

80. The push-in implant of claim 1, wherein said implant comprises an artificial material other than bone.

81. The push-in implant of claim 1, wherein said implant is made of an artificial material that is stronger than bone.

82. The push-in implant of claim 1, wherein said implant is made of an artificial material that is harder than bone.

83. The push-in implant of claim 1, wherein said implant comprises bone.

84. The push-in implant of claim 83, wherein said bone includes cortical bone.

85. The push-in implant of claim 1, wherein said implant comprises bone growth promoting material.

86. The push-in implant of claim 85, wherein said bone growth promoting material is selected from one of bone morphogenetic protein, hydroxyapatite, and genes coding for the production of bone.

87. The push-in implant of claim 1, wherein said implant is treated with a bone growth promoting substance.

88. The push-in implant of claim 1, wherein said implant is a source of osteogenesis.

89. The push-in implant of claim 1, wherein said implant is at least in part bioabsorbable.

90. The push-in implant of claim 1, wherein said implant comprises metal.

91. The push-in implant of claim 90, wherein said metal is ASTM material suitable for use in said push-in spinal fusion implant.

92. The push-in implant of claim 90, wherein said metal includes titanium.

93. The push-in implant of claim 1, wherein said implant comprises a plastic material.

94. The push-in implant of claim 1, wherein said implant comprises a ceramic material.

95. The push-in implant of claim 1, wherein said implant is formed of a porous material.

96. The push-in implant of claim 1, wherein said implant is formed of a material that intrinsically participates in the growth of bone from adjacent vertebral body to adjacent vertebral body through said implant.

97. The push-in implant of claim 1, wherein said hollow has an interior surface, said hollow being capable of containing bone growth promoting material.

98. The push-in implant of claim 97, wherein said bone growth promoting material is selected from one of bone morphogenetic protein, hydroxyapatite, and genes coding for the production of bone.

99. The push-in implant of claim 1, wherein said at least one opening is adapted to retain fusion-promoting materials.

100. The push-in implant of claim 1, wherein at least a portion of said implant is treated to promote bone ingrowth between said implant and said adjacent vertebral bodies.

101. The push-in implant of claim 1, in combination with a chemical substance to inhibit scar formation.

102. The push-in implant of claim 1, in combination with a fusion promoting substance.

103. The push-in implant of claim 102, wherein said fusion promoting substance includes at least one of bone, bone morphogenetic protein, hydroxyapatite, and genes coding for the production of bone.

104. The pushpin implant of claim 1, wherein said blocker includes an opening adapted to cooperatively engage a tool used to move said blocker from an initial position to a final position to increase the height of said implant, said opening being adapted to slideably engage the tool.

105. A push-in interbody spinal fusion implant for at least in part linear insertion across the surgically corrected height of a disc space between two adjacent vertebral bodies of a spine, said implant comprising:

an upper member having a portion being at least in part arcuate adapted for placement toward and at least in part within one of the adjacent vertebral bodies, said upper member having at least one opening adapted to communicate with one of the adjacent vertebral bodies, said upper member having a proximal end and a distal end;

a lower member having a portion being at least in part arcuate adapted for placement toward and at least in part within the other of the adjacent vertebral bodies, said lower member having at least one opening adapted to communicate with the other of the adjacent vertebral bodies, said openings of said upper and lower members being in communication with one another and adapted for permitting for the growth of bone from adjacent vertebral body to adjacent vertebral body through said implant and being sufficiently sized and located to allow for interbody spinal fusion through said implant, said lower member having a proximal end and a distal end corresponding to said proximal end and said distal end of said upper member, respectively, and a length between said proximal and distal ends, said upper and lower members articulating therebetween adjacent one of said proximal ends and said distal ends of said upper and lower members and allowing for expansion of the height of said implant, said upper and lower members having a first position relative to one another allowing for a collapsed implant height and a second position relative to one another allowing for an increased height said arcuate portions of said upper and lower members in the first position being parallel to one another over a substantial portion of the length of said implant and forming at least a portion of a cylinder along the length of said implant;

at least a portion of a bone-engaging projection is adapted for linear insertion formed on the exterior of each of said opposed arcuate portions of said upper and lower members for penetrably engaging the adjacent vertebral bodies and to facilitate securing said implant into the spine; and

at least one expander adapted to cooperatively engage and hold at least a portion of said upper and lower members apart so as to maintain the increased height of said implant and resist the collapse of said implant to the collapsed implant height when said implant is in a final deployed position, each of said upper and lower members having a track configured to cooperate with said expander and permit said expander to move therein, said tracks permitting said expander to move from side to side within said tracks.

106. The push-in implant of claim 105, wherein said track of said upper member and said track of said lower member are in the same plane.

107. The push-in implant of claim 105, wherein said track of said upper member and said track of said lower member are parallel to one another.

108. The push-in implant of claim 105, where said track of said upper member and said track of said lower member are iii a plane perpendicular to a longitudinal axis of said implant.

109. The push-in implant of claim 105, wherein said expander has a first height corresponding to the height of said expander when said implant is initially inserted into the spine, said expander having a second height corresponding to the height of said expander when said expander is moved into a final deployed position to increase the height of said implant, said second height being greater than said first height.

110. The push-in implant of claim 105, wherein said expander has an upper surface, a lower surface, and side surfaces as defined when said expander is positioned to increase the height of said implant, said side surfaces intersecting said upper and said lower surfaces at two diametrically opposed junctions.

111. The push-in implant of claim 110, wherein said two diametrically opposed junctions are a pair of diametrically opposed corners and a pair of diametrically opposed arcs.

112. The push-in implant of claim 105, wherein said implant comprises bone.

113. The push-in implant of claim 105, wherein said implant is treated with a bone growth promoting substance.

114. The push-in implant of claim 105, wherein said implant is at least in part bioabsorbable.

115. The push-in implant of claim 105, in combination with a chemical substance to inhibit scar formation.

116. The push-in implant of claim 105, in combination with a fusion promoting substance.

117. The push-in implant of claim 116, wherein said fusion promoting substance includes at least one of bone, bone morphogenetic protein, hydroxyapatite, and genes coding for the production of bone.

127. The push-in implant of claim 117, wherein said implant comprises bone.

118. A push-in interbody spinal fusion implant for at least in part linear insertion across the surgically corrected height of a disc space between two adjacent vertebral bodies of a spine, said implant comprising:

an upper member having a portion being at least in part arcuate adapted for placement toward and at least in part within one of the adjacent vertebral bodies, said upper member having at least one opening adapted to communicate with one of the adjacent vertebral bodies, said upper member having a proximal end and a distal end;

a lower member having a portion being at least in part arcuate adapted for placement toward and at least in part within the other of the adjacent vertebral bodies, said lower member having at least one opening adapted to communicate with the other of the adjacent vertebral bodies, said openings of said upper and lower members being in communication with one another and adapted for permitting for the growth of bone from adjacent vertebral body to adjacent vertebral body through said implant and being sufficiently sized and located to allow for interbody spinal fusion through said implant, said lower member having a proximal end and a distal end corresponding to said proximal end and said distal end of said upper member, respectively, and a length between said proximal and distal ends, said upper and lower members articulating therebetween adjacent one of said proximal ends and said distal ends of said upper and lower members and allowing for expansion of the height of said implant, said upper and lower members having a first position relative to one another allowing for a collapsed implant height and a second position relative to one another allowing for an increased height, said arcuate portions of said upper and lower members in the first position being parallel to one another over a substantial portion of the length of said implant and forming at least a portion of a cylinder along the length of said implant;

at least a portion of a bone engaging projection is adapted for linear insertion formed on the exterior of each of said opposed arcuate portions of said upper and lower members for penetrably engaging the adjacent vertebral bodies and to facilitate securing said implant into the spine; and

at least one expander adapted to cooperatively engage and hold at least a portion of said upper and lower members apart so as to maintain the increased height of said implant and resist the collapse of said implant to the collapsed implant height when said implant is in a final deployed position, each of said upper and lower members having a track configured to cooperate with said expander and permit said expander to rotate therein, at least one of said tracks of said upper and lower members having a cooperating surface, said expander having a corresponding cooperating surface that contacts said cooperating surface of said at least one track to orient said expander in a predetermined location.

119. The push-in implant of claim 118, wherein said cooperating surfaces orient said expander within said implant such that the axis of rotation of said expander is parallel with the longitudinal axis of said implant.

120. The push-in implant of claim 119, wherein said cooperating surfaces center said expander within said implant such that the axis of rotation of said expander coincides with the longitudinal axis of said implant.

121. The push-in implant of claim 118, wherein at least one of said tracks of said upper and lower members includes at least one side, said cooperating surface being on a portion of said at least one side of said at least one of said tracks.

122. The push-in implant of claim 121, wherein said cooperating surface of said at least one side is a detent and said corresponding cooperating surface of said expander is a projection.

123. The push-in implant of claim 122, wherein said detent and said projection center said expander within said implant such that the axis of rotation of said expander coincides with the longitudinal axis of said implant.

124. The push-in implant of claim 118, wherein said expander has a first height corresponding to the height of said expander when said implant is initially inserted into the spine, said expander having a second height corresponding to the height of said expander when said expander is moved into a final deployed position to increase the height of said implant, said second height being greater than said first height.

125. The push-in implant of claim 118, wherein said expander has an upper surface, a lower surface, and side surfaces as defined when said expander is positioned to increase the height of said implant, said side surfaces intersecting said upper and said lower surfaces at two diametrically opposed junctions.

126. The push-in implant of claim 125, wherein said two diametrically opposed junctions are a pair of diametrically opposed corners and a pair of diametrically opposed arcs.

128. The push-in implant of claim 118, wherein said implant is treated with a bone growth promoting substance.

129. The push-in implant of claim 118, wherein said implant is at least in part bioabsorbable.

130. The push-in implant of claim 118, in combination with a chemical substance to inhibit scar formation.

131. The push-in implant of claim 118, in combination with a fusion promoting substance.

132. The push-in implant of claim 131, wherein said fusion promoting substance includes at least one of bone, bone morphogenetic protein, hydroxyapatite, and genes coding for the production of bone.

133. A push-in interbody spinal fusion implant for at least in part linear insertion across the surgically corrected height of a disc space between two adjacent vertebral bodies of a spine, said implant comprising:

an upper member having a portion being at least in part arcuate adapted for placement toward and at least in part within one of the adjacent vertebral bodies, said upper member having at least one opening adapted to communicate with one of the adjacent vertebral bodies, said upper member having a proximal end and a distal end;

a lower member having a portion being at least in part arcuate adapted for placement toward and at least in part within the other if the adjacent vertebral bodies, said lower member having at least one opening adapted to communicate with the other of the adjacent vertebral bodies, said openings of said upper and lower members being in communication with one another and adapted for permitting for the growth of bone from adjacent vertebral body to adjacent vertebral body through said implant and being sufficiently sized and located to allow for interbody spinal fusion through said implant, said lower member having a proximal end and a distal end corresponding to said proximal end and said distal end of said upper member, respectively, and a length between said proximal and distal ends, said upper and lower members articulating therebetween adjacent one of said proximal ends and said distal ends of said upper and lower members and allowing for expansion of the height of said implant, said upper and lower members having a first position relative to one another allowing for a collapsed implant height and a second position relative to one another allowing for an increased height, said arcuate portions of said upper and lower members in the first position being parallel to one another over a substantial portion of the length of said implant and forming at least a portion of a cylinder along the length of said implant;

at least a portion of a bone-engaging projection adapted for linear insertion is formed on the exterior of each of said opposed arcuate portions of said upper and lower members for penetrably engaging the adjacent vertebral bodies and to facilitate securing said implant into the spine;

at least one expander adapted to expand said upper and lower members from the first position to the second position when moved from an expander insertion position to a final deployed expander position, said expander being adapted to cooperatively engage and hold at least a portion of said upper and lower members apart so as to maintain the increased height of said implant and resist the collapse of said implant to the collapsed implant height when said implant is in a final deployed position, said expander having a first height corresponding to the height of said expander when said implant is initially inserted into the spine, said expander having a second height corresponding to the height of said expander when said expander is rotated into a final deployed position to increase the height of said implant, said second height of said expander being greater than said first height of said expander, said first height and said second height being located in a single plane during rotation of said expander; and

a hollow defined between said upper and lower members in communication with said openings in each of said upper and lower members, said hollow being adapted to receive fusion-promoting substances, said hollow having a width that is substantially unobstructed by any mechanism for moving said expander.

134. The push-in implant of claim 133, wherein said implant has a constant width in both the collapsed height and the increased height.

135. The push-in implant of claim 133, wherein said implant has a width and said expander has a width less than the width of said implant.

136. The push-in implant of claim 133, wherein said implant has a width and said expander has a width less than one half the width of said implant.

137. The push-in implant of claim 133, wherein said implant has side walls and said expander does not contact said side walls when said implant is in the final deployed position.

138. The push-in implant of claim 133, wherein said implant has a longitudinal axis and said expander rotates in a plane generally perpendicular to the longitudinal axis of said implant to increase the height of said implant.

139. The push-in implant of claim 133, wherein said expander is located along the length of said implant.

140. The push-in implant of claim 133, wherein said expander is located proximate said proximal ends of said upper and lower members.

141. The push-in implant of claim 133, wherein said expander is located proximate said distal ends of said upper and lower members.

142. The push-in implant of claim 133, wherein said expander remains in the same location along the longitudinal axis of the implant when rotated.

143. The push-in implant of claim 133, wherein said expander is located at a predetermined location along the length of said implant and remains so located in transitioning said implant from the first position to the second position.

144. The push-in implant of claim 133, wherein said expander is adapted to cooperatively engage a tool used to move said expander from an initial position to a final position to increase the height of said implant, said tool not being a part of said implant and being removed from said implant after moving said expander into the final position.

145. The push-in implant of claim 133, wherein said expander is adapted to cooperatively engage a tool that rotates about an axis parallel to the longitudinal axis of said implant to rotate said expander to increase the height of said implant.

146. The push-in implant of claim 145, wherein said expander rotates in a plane perpendicular to the longitudinal axis of said implant to increase the height of said implant.

147. The push-in implant of claim 146, wherein said expander remains in the same location along the longitudinal axis of the implant when rotated.

148. The push-in implant of claim 133, wherein said expander moves said arcuate portions of said upper and lower members from a parallel orientation to an angled orientation relative to one another.

149. The push-in implant of claim 133, wherein each of said upper and lower members are adapted to cooperate with said expander.

150. The push-in implant of claim 149, wherein each of said upper and lower members have a track configured to permit said expander to rotate therein.

151. The push-in implant of claim 150, wherein said track of said upper member and said track of said lower member are in the same plane.

152. The push-in implant of claim 150, wherein said track of said upper member and said track of said lower member are parallel to one another.

153. The push-in implant of claim 150, where said track of said upper member and said track of said lower member are in a plane perpendicular to the longitudinal axis of said implant.

154. The push-in implant of claim 150, wherein at least one of said tracks of said upper and lower members includes at least one side having a cooperating surface, said expander having a corresponding cooperating surface that contacts said cooperating surface of said at least one side to orient said expander in a predetermined location.

155. The push-in implant of claim 154, wherein said cooperating surface of said at least one side is a detent and said corresponding cooperating surface of said expander is a projection.

156. The push-in implant of claim 155, wherein said adjacent and said projection center said expander within said implant such that the axis of rotation of said expander coincides with the longitudinal axis of said implant.

157. The push-in implant of claim 149, wherein said upper and lower members are adapted to cooperate with said expander so as to center said expander within a cross section of the upper and lower members.

158. The push-in implant of claim 133, wherein said upper and lower members structurally cooperate with said expander so as to keep said expander located within said implant.

159. The push-in implant of claim 133, wherein said upper and lower members are configured to cooperate with one another so as to stop said upper and lower members from being moved apart from one another more than a predetermined distance.

160. The push-in implant of claim 133, wherein said expander has an upper surface, a lower surface, and side surfaces as defined when said expander is positioned to increase the height of said implant, said side surfaces intersecting said upper and said lower surfaces at two diametrically opposed junctions.

161. The push-in implant of claim 160, wherein said two diametrically opposed junctions are a pair of diametrically opposed corners and a pair of diametrically opposed arcs.

162. The push-in implant of claim 161, wherein said two diametrically opposed arcs are each of the same radius.

163. The push-in implant of claim 162, wherein the distance across said two diametrically opposed arcs generally approximates the distance between said upper and lower surfaces of said expander.

164. The push-in implant of claim 161, wherein said two diametrically opposed corners form a 90-degree angle.

165. The push-in implant of claim 160, wherein each of said upper and lower surfaces lie generally in a plane.

166. The push-in implant of claim 160, wherein said upper and lower surfaces are generally parallel to one another.

167. The push-in implant of claim 160, wherein said side surfaces and said upper and lower surfaces are oriented to substantially form a parallelogram.

168. The push-in implant of claim 133, wherein the difference between said first height and said second height of said expander approximates the difference in height of said implant between said first position and said second position as measured proximate the location of said expander.

169. The push-in implant of claim 133, wherein said expander has a depth dimension less than that of said first and second height of said expander.

170. The push-in implant of claim 169, wherein said expander has a fixed shape during movement from an initial insertion position to a final deployed position within said implant.

171. The push-in implant of claim 169, wherein the depth dimension of said expander is less than one-half of said first and second height of said expander.

172. The push-in implant of claim 133, further comprising a second expander located between said upper and lower members for moving at least a portion of the upper and lower members away from one another to increase the maximum height of said implant where said second expander is located.

173. The push-in implant of claim 172, wherein said second expander rotates to increase the height of said implant.

174. The push-in implant of claim 172, wherein said second expander is located proximate an end of said implant opposite said expander.

175. The push-in implant of claim 174, wherein said hollow is substantially unobstructed by said second expander extending along a substantial portion of the length of said hollow so as to permit growth of bone from adjacent vertebral body to adjacent vertebral body through said implant.

176. The push-in implant of claim 174, wherein said second expander remains in the same location along the longitudinal axis of the implant when rotated.

177. The push-in implant of claim 172, wherein said implant has a longitudinal axis and said second expander rotates in a plane perpendicular to the longitudinal axis of said implant to increase the height of said implant.

178. The push-in implant of claim 172, wherein said second expander is located proximate one of the proximal end and the distal end of said upper and lower members.

179. The push-in implant of claim 178, wherein said hollow is unobstructed by said second expander extending along a substantial portion of the length of said hollow to permit growth of bone from adjacent vertebral body to adjacent vertebral body through said implant.

180. The push-in implant of claim 178, further comprising a second hollow between said upper and lower member located between said second expander and said end of said implant proximate said second expander.

181. The push-in implant of claim 172, wherein each of said upper and lower members have a track within which said second expander rotates.

182. The push-in implant of claim 181, wherein said track is configured to permit said second expander to rotate therein and then to move from side to side within said track.

183. The push-in implant of claim 172, wherein said second expander has a first height corresponding to the height of said second expander when said implant is initially inserted into the spine, said second expander having a second height corresponding to the height of said second expander when said second expander is moved into a final deployed position to increase the height of said implant, said second height being greater than said first height.

184. The push-in implant of claim 172, wherein said second expander has an upper surface, a lower surface, and side surfaces as defined when said second expander is positioned to increase the height of said implant, and said side surfaces intersecting said upper and said lower surfaces at two diametrically opposed junctions.

185. The push-in implant of claim 184, wherein the difference between said first height and said second height of said second expander approximates the difference in height of said implant between said first position and said second position as measured proximate the location of said second expander.

186. The push-in implant of claim 133, wherein said tipper and lower members have walls contacting one another.

187. The push-in implant of claim 186, wherein said % walls are aligned parallel with the longitudinal axis of said implant.

188. The push-in implant of claim 186, wherein said walls are at least in part overlapping.

189. The push-in implant of claim 133, wherein said upper and lower members have a rotational articulation therebetween adjacent one of said proximal end and said distal end of said upper and lower members.

190. The push-in implant of claim 189, wherein said rotational articulation is at one of said proximal end and said distal end of said upper and lower members opposite said expander.

191. The push-in implant of claim 189, wherein said rotational articulation allows for expansion.

192. The push-in implant of claim 191, wherein said rotational articulation allows for limited expansion.

193. The push-in implant of claim 189, wherein said rotational articulation is formed by said upper and lower members interdigitating so as to cooperatively engage.

194. The push-in implant of claim 193, wherein said rotational articulation is configured such that engagement occurs when said upper and lower members are substantially perpendicular to one another.

195. The push-in implant of claim 194, wherein said rotational articulation is configured to remain engaged within a range of movement of said upper and lower members resulting from positioning said implant in the second position.

196. The push-in implant of claim 133, wherein one of said upper and lower members has an interior wall, which is unexposed, extending therefrom toward the other of said upper and lower members when said implant is in an initial insertion position, and when said implant is in a final position said implant has a shape such that each of said arcuate portions of said upper and lower members are separated by at least a portion of said interior wall, which now has an exposed side.

197. The push-in implant of claim 196, wherein said upper and lower members have side walls for engaging each other.

198. The push-in implant of claim 197, wherein said side walls of said upper and lower members are at least partially overlapping walls.

199. The push-in implant of claim 196, wherein said arcuate portions of said upper and lower members form an angular orientation relative to one another when said implant is in the final position.

200. The push-in implant of claim 196, wherein said arcuate portions of said upper and lower members when said implant is in the initial insertion position form a cylindrical shape.

201. The push-in implant of claim 133, wherein said implant has an interior, at least one of said upper and lower members has a screw hole passing therethrough adapted to receive a screw passing from said interior of said implant into one of the adjacent vertebral bodies.

202. The push-in implant of claim 201, wherein each of said upper and lower members has at least one screw hole passing therethrough adapted to receive a screw passing from said interior of said implant into the adjacent vertebral body in contact with each of said upper and lower members respectively.

203. The push-in implant of claim 201, further comprising at least one screw adapted to pass from said interior of said implant through said screw hole and into the adjacent vertebral body to anchor said implant to the adjacent vertebral body.

204. The push-in implant of claim 133, wherein said implant has a side surface when in a final position that is contoured to cooperate with another implant.

205. The push-in implant of claim 204, wherein said implant and said cooperating other implant have a combined width therebetween less than the combined height of said implant and said cooperating other implant.

206. The push-in implant of claim 133, further comprising a cap for closing one of said proximal end and said distal end of said upper and lower members, said cap having an exterior surface and an interior surface.

207. The push-in implant of claim 206, wherein said interior surface of said cap has spaced slots about its circumference to facilitate a snap fit of said cap into said implant.

208. The push-in implant of claim 133, wherein said implant comprises an artificial material other than bone.

209. The push-in implant of claim 133, wherein said implant is made of an artificial material that is stronger than bone.

210. The push-in implant of claim 133, wherein said implant is made of an artificial material that is harder than bone.

211. The push-in implant of claim 133, wherein said implant comprises bone.

212. The push-in implant of claim 211, wherein said bone includes cortical bone.

213. The push-in implant of claim 133, wherein said implant comprises bone growth promoting material.

214. The push-in implant of claim 213, wherein said bone growth promoting material is selected from one of bone morphogenetic protein, hydroxyapatite, and genes coding for the production of bone.

215. The push-in implant of claim 133, wherein said implant is treated with a bone growth promoting substance.

216. The push-in implant of claim 133, wherein said implant is a source of osteogenesis.

217. The push-in implant of claim 133, wherein said implant is at least in part bioabsorbable.

218. The push-in implant of claim 133, wherein said implant comprises metal.

219. The push-in implant of claim 218, wherein said metal is ASTM material suitable for use in said push-in spinal fusion implant.

220. The push-in implant of claim 218, wherein said metal includes titanium.

221. The push-in implant of claim 133, wherein said implant comprises a plastic material.

222. The push-in implant of claim 133, wherein said implant comprises a ceramic material.

223. The push-in implant of claim 133, wherein said implant is formed of a porous material.

224. The push-in implant of claim 133, wherein said implant is formed of a material that intrinsically participates in the growth of bone, from adjacent vertebral body to adjacent vertebral body through said implant.

225. The push-in implant of claim 133, wherein said hollow has an interior surface, said hollow being capable of containing bone growth promoting material.

226. The push-in implant of claim 225, wherein said bone growth promoting material is selected from one of bone morphogenetic protein, hydroxyapatite, and genes coding for the production of bone.

227. The push-in implant of claim 133, wherein said at least one opening is adapted to retain fusion-promoting materials.

228. The push-in implant of claim 133, wherein at least a portion of said implant is treated to promote bone ingrowth between said implant and said adjacent vertebral bodies.

229. The push-in implant of claim 133, in combination with a chemical substance to inhibit scar formation.

230. The push-in implant of claim 133, wherein said expander has an external thread, each of said upper and lower members having a push-in converging portion adapted to cooperate with said external thread of said expander to expand said implant from a first collapsed height to a second expanded height when said expander is rotated from a first to a second position.

231. The push-in implant of claim 133, in combination with a fusion promoting substance.

232. The push-in implant of claim 231, wherein said fusion promoting substance includes at least one of bone, bone morphogenetic protein, hydroxyapatite, and genes coding for the production of bone.

233. The push-in implant of claim 133, wherein said expander includes an opening adapted to cooperatively engage a tool used to move said expander from an initial position to a final position to increase the height of said implant, said opening being adapted to slideably engage the tool.

234. A push-in interbody spinal fusion implant for at least in part linear insertion across the surgically corrected height of a disc space between two adjacent vertebral bodies of a spine, said implant comprising:

an upper member having a portion being at least in part arcuate adapted for placement toward and at least in part within one of the adjacent vertebral bodies, said upper member having at least one opening adapted to communicate with one of the adjacent vertebral bodies, said upper member having a proximal end and a distal end;

a lower member having a portion being at least in part arcuate adapted for placement toward and at least in part within the other of the adjacent vertebral bodies, said lower member having at least one opening adapted to communicate with the other of the adjacent vertebral bodies, said openings of said upper and, lower members being in communication with one another and adapted for permitting for the growth of bone from adjacent vertebral body to adjacent vertebral body through said implant and being sufficiently sized and located to allow for interbody spinal fusion through said implant, said lower member having a proximal end and a distal end corresponding to said proximal end and said distal end of said upper member, respectively, and a length between said proximal and distal ends, said upper and lower members articulating therebetween adjacent one of said proximal ends and said distal ends of said upper and lower members and allowing for expansion of the height of said implant, said upper and lower members having a first position relative to one another allowing for a collapsed implant height and a second position relative to one another allowing for an increased height, said arcuate portions of said upper and lower members in the first position being parallel to one another over a substantial portion of the length of said implant and forming at least a portion of a cylinder along the length of said implant;

at least a portion of a bone engaging projection adapted for linear insertion is formed on the exterior of each of said oppose arcuate portions of said upper and lower members for penetrably engaging the adjacent vertebral bodies and to facilitate securing said implant into the spine; and

at least one expander adapted to expand said upper and lower members from the first position to the second position when moved from an expander insertion position to a final deployed expander position, said expander being adapted to cooperatively engage and hold at least a portion of said upper and lower members apart so as to maintain the increased height of said implant and resist the collapse of said implant to the collapsed implant height when said implant is in a final deployed position, said expander having a first height corresponding to the height of said expander when said implant is initially inserted into the spine, said expander having a second height corresponding to the height of said expander when said expander is rotated into a final deployed position to increase the height of said implant, said second height of said expander being greater than said first height of said expander, each of said upper and lower members having a track configured to cooperate with said expander and to permit said expander to move therein, said tracks permitting said expander to move from side to side within said tracks.

235. The push-in implant of claim 234, wherein said expander has an upper surface, a lower surface, and side surfaces as defined when said expander is positioned to increase the height of said implant, said side surfaces intersecting said upper and said lower surfaces at two diametrically opposed junctions.

236. The push-in implant of claim 235, wherein said two diametrically opposed junctions are a pair of diametrically opposed corners and a pair of diametrically opposed arcs.

237. The push-in implant of claim 234, wherein said implant comprises bone.

238. The push-in implant of claim 234, wherein said implant is treated with a bone growth promoting substance.

239. The push-in implant of claim 234, wherein said implant is at least in part bioabsorbable.

240. The push-in implant of claim 234, in combination with a chemical substance to inhibit scar formation.

241. The push-in implant of claim 234, in combination with a fusion promoting substance.

242. The push-in implant of claim 241, wherein said fusion promoting substance includes at least one of bone, bone morphogenetic protein, hydroxyapatite, and genes coding for the production of bone.

243. A push-in interbody spinal fusion implant for at least in part linear insertion across the surgically corrected height of a disc space between two adjacent vertebral bodies of a spine, said implant comprising:

an upper member having a portion being at least in part arcuate adapted for placement toward and at least in part within one of the adjacent vertebral bodies, said upper member having at least one opening adapted to communicate with one of the adjacent vertebral bodies, said upper member having a proximal end and a distal end;

a lower member having a portion being at least in part arcuate adapted for placement toward and at least in part within the other of the adjacent vertebral bodies, said lower member having at least one opening adapted to communicate with the other of the adjacent vertebral bodies, said openings of said upper and lower members being in communication with one another and adapted for permitting for the growth of bone from adjacent vertebral body to adjacent vertebral body through said implant and being sufficiently sized and located to allow for interbody spinal fusion through said implant, said lower member having a proximal end and a distal end corresponding to said proximal end and said distal end of said upper member, respectively, and a length between said proximal and distal ends, said upper and lower members articulating therebetween adjacent one of said proximal ends and said distal ends of said upper and lower members and allowing for expansion of the height of said implant, said upper and lower members having a first position relative to one another allowing for a collapsed implant height and a second position relative to one another allowing for an increased height, said arcuate portions of said upper and lower members in the first position being parallel to one another over a substantial portion of the length of said implant and forming at least a portion of a cylinder along the length of said implant;

at least a portion of a bone-engaging projection adapted for linear insertion is formed on the exterior of each of said opposed arcuate portions of said upper and lower members for penetrably engaging the adjacent vertebral bodies and to facilitate securing said implant into the spine; and

at least one expander adapted to expand said upper and lower members from the first position to the second position when moved from an expander insertion position to a final deployed expander position, said expander being adapted to cooperatively engage and hold at least a portion of said upper and lower members apart so as to maintain the increased height of said implant and resist the collapse of said implant to the collapsed implant height when said implant is in a final deployed position, said expander having a first height corresponding to the height of said expander when said implant is initially inserted into the spine, said expander having a second height corresponding to the height of said expander when said expander is rotated into a final deployed position to increase the height of said implant, said second height of said expander being greater than said first height of said expander, each of said upper and lower members having a track configured to cooperate with said expander and to permit said expander to rotate therein, at least one of said tracks of said upper and lower members having a cooperating surface, said expander having a corresponding cooperating surface that contacts said cooperating surface of said at least one track to orient said expander in a predetermined location.

244. The push-in implant of claim 243, wherein said cooperating surfaces orient said expander within said implant such that the axis of rotation of said expander is parallel with the longitudinal axis of said implant.

245. The push-in implant of claim 244, wherein said cooperating surfaces center said expander within said implant such that the axis of rotation of said expander coincides with the longitudinal axis of said implant.

246. The push-in implant of claim 243, wherein said expander has an upper surface, a lower surface, and side surfaces as defined when said expander is positioned to increase the height of said implant, said side surfaces intersecting said upper and said lower surfaces at two diametrically opposed junctions.

247. The push-in implant of claim 246, wherein said two diametrically opposed junctions are a pair of diametrically opposed corners and a pair of diametrically opposed arcs.

248. The push-in implant of claim 243, wherein said implant comprises bone.

249. The push-in implant of claim 243, wherein said implant is treated with a bone growth promoting substance.

250. The push-in implant of claim 243, wherein said implant is at least in part bioabsorbable.

251. The push-in implant of claim 243, in combination with a chemical substance to inhibit scar formation.

252. The push-in implant of claim 243, in combination with a fusion promoting substance.

253. The push-in implant of claim 252, wherein said fusion promoting substance includes at least one of bone, bone morphogenetic protein, hydroxyapatite, and genes coding for the production of bone.

254. A pair of push-in interbody spinal fusion implants for at least in part linear insertion across the surgically corrected height of a disc space between two adjacent vertebral bodies of a spine, said pair of implants comprising:

a first push-in interbody spinal fusion implant comprising;

an upper member having a portion being at least in part arcuate adapted for placement toward and at least in part within one of the adjacent vertebral bodies, said upper-member having at least one opening adapted to communicate with one of the adjacent vertebral bodies, said upper member having a proximal end and a distal end;

a lower member having a portion being at least in part arcuate adapted for placement toward and at least in part within the other of the adjacent vertebral bodies, said lower member having at least one opening adapted to communicate with the other of the adjacent vertebral bodies, said openings of said upper and lower members being in communication with one another and adapted for permitting for the growth of bone from adjacent vertebral body to adjacent vertebral body through said implant and being sufficiently sized and located to allow for interbody spinal fusion through said implant, said lower member having a proximal end and a distal end corresponding to said proximal end and said distal end of said upper member, respectively, and a length between said proximal and distal ends, said upper and lower members articulating therebetween adjacent one of said proximal ends and said distal ends of said upper and lower members and allowing for expansion of the height of said implant, said upper and lower members having a first position relative to one another allowing for a collapsed implant height and a second position relative to one another allowing for an increased height, said arcuate portions of said upper and lower members in the first position being parallel to one another over a substantial portion of the length of said implant and forming at least a portion of a cylinder along the length of said implant;

at least a portion of a bone-engaging projection adapted for linear insertion formed on the exterior of each of said opposed arcuate portions of said upper and lower members for penetrably engaging the adjacent vertebral bodies and to facilitate securing said implant into the spine; and

at least one blocker adapted to cooperatively engage and hold at least a portion of said upper and lower members apart so as to maintain the increased height of said implant and resist the collapse of said implant to the collapsed implant height when said implant is in a final deployed position, said blocker having a first height corresponding to the height of said blocker when said first implant is initially inserted into the spine, said blocker having a second height corresponding to the height of said blocker when said blocker is moved into the final deployed position to increase the height of said first implant, said second height of said blocker being greater than said first height of said blocker, said first height and said second height being in a plane; and

a second push-in interbody spinal fusion implant comprising;

an upper member having a portion being at least iii part arcuate adapted for placement toward and at least in part within one of the adjacent vertebral bodies, said upper member having at least one opening adapted to communicate with one of the adjacent vertebral bodies, said upper member having a proximal end and a distal end;

a lower member having a portion being at least in part arcuate adapted for placement toward and at least in part within the other of the adjacent vertebral bodies, said lower member having at least one opening adapted to communicate with the other of the adjacent vertebral bodies, said openings of said upper and lower members being in communication with one another and adapted for permitting for the growth of bone from adjacent vertebral body to adjacent vertebral body through said implant and being sufficiently sized and located to allow for interbody spinal fusion through said implant, said lower member having a proximal end and a distal end corresponding to said proximal end and said distal end of said upper member, respectively, and a length between said proximal and distal ends; and

at least a portion of a bone engaging projection adapted for linear insertion formed on the exterior of each of said opposed arcuate portions of said upper and lower members for penetrably engaging the adjacent vertebral bodies and to facilitate securing said implant into the spine, said first and second implants when in side-to-side contact having a combined width substantially less than the combined heights as measured from the upper to the lower bone-engaging surfaces of said first and second implants.

255. The push-in implants of claim 254, in combination with a fusion promoting substance.

256. The push-in implants of claim 255, wherein said fusion promoting substance includes at least one of bone, bone morphogenetic protein, hydroxyapatite, and genes coding for the production of bone.

257. The push-in implants of claim 254, wherein said blocker is an expander adapted to expand said first implant from a first collapsed height to a second expanded height when moved from a first to a second position.

258. The push-in implants of claim 257, wherein said expander has a first height corresponding to the height of said expander when said first implant is initially inserted into the spine, said expander having a second height corresponding to the height of said expander when said expander is moved into a final deployed position to increase the height of said first implant, said second height being greater than said first height.

259. The push-in implants of claim 257, wherein said expander has an upper surface, a lower surface, and side surfaces as defined when said expander is positioned to increase the height of said first implant, said side surfaces intersecting said upper and said lower surfaces of two diametrically opposed junctions.

260. The push-in implants of claim 259, wherein said two diametrically opposed junctions are a pair of diametrically opposed corners and a pair of diametrically opposed arcs.

261. The push-in implants of claim 254, wherein said first implant comprises bone.

262. The push-in implants of claim 254, wherein said first implant is treated with a bone growth promoting substance.

263. The push-in implants of claim 254, wherein said first implant is at least in part bioabsorbable.

264. The push-in implants of claim 254, in combination with a chemical substance to inhibit scar formation.

265. A push-in interbody spinal fusion implant for at least in part linear insertion across the surgically corrected height of a disc space between two adjacent vertebral bodies of a spine, said implant comprising:

an upper member having a portion being at least in part arcuate adapted for placement toward and at least in part within one of the adjacent vertebral bodies, said upper member having at least one opening adapted to communicate with one of the adjacent vertebral bodies, said upper member having a proximal end and a distal end;

a lower member having a portion being at least in part arcuate adapted for placement toward and at least in part within the other of the adjacent vertebral bodies, said lower member having at least one opening adapted to communicate with the other of the adjacent vertebral bodies, said openings of said upper and lower members being in communication with one another and adapted for permitting for the growth of bone from adjacent vertebral body to adjacent vertebral body through said implant and being sufficiently sized and located to allow for interbody spinal fusion through said implant, said lower member having a proximal end and a distal end corresponding to said proximal end and said distal end of said upper member, respectively, and a length between said proximal and distal ends, said upper and lower members articulating therebetween adjacent one of said proximal ends and said distal ends of said upper and lower members and allowing for expansion of the height of said implant, said upper and lower members having a first position relative to one another allowing for a collapsed implant height and a second position relative to one another allowing for an increased height, said arcuate portions of said upper and lower members in the first position being parallel to one another over a substantial portion of the length of said implant and forming at least a portion of a cylinder along the length of said implant;

opposed side walls between said upper and lower members;

at least a portion of a bone engaging projection is adapted for linear insertion formed on the exterior of each of said opposed arcuate portions of said upper and lower members for penetrably engaging the adjacent vertebral bodies and to facilitate securing said implant into the spine; and

at least one blocker adapted to cooperatively engage and hold at least a portion of said upper and lower members apart so as to maintain the increased height of said implant and resist the collapse of said implant to the collapsed implant height when said implant is in a final deployed position, said at least one blocker being adapted to not contact said side walls adjacent said blocker when said implant is in the deployed position.

266. The push-in implant of claim 265, wherein said blocker is an expander adapted to expand said implant from a first collapsed height to a second expanded height when moved from a first to a second position.

267. The push-in implant of claim 266, wherein said expander has a first height corresponding to the height of said expander when said implant is initially inserted into the spine, said expander having a second height corresponding to the height of said expander when said expander is moved into a final deployed position to increase the height of said implant, said second height being greater than said first height.

268. The push-in implant of claim 266, wherein said expander has an upper surface, a lower surface, and side surfaces as defined when said expander is positioned to increase the height of said implant, said side surfaces intersecting said upper and said lower surfaces at two diametrically opposed junctions.

269. The push-in implant of claim 268, wherein said two diametrically opposed junctions are a pair of diametrically opposed corners and a pair of diametrically opposed arcs.

270. The push-in implant of claim 265, wherein said implant comprises bone.

271. The push-in implant of claim 265, wherein said implant is treated with a bone growth promoting substance.

272. The push-in implant of claim 265, wherein said implant is at least in part bioabsorbable.

273. The push-in implant of claim 265, in combination with a chemical substance to inhibit scar formation.

274. The push-in implant of claim 265, in combination with a fusion promoting substance.

275. The push-in implant of claim 274, wherein said fusion promoting substance includes at least one of bone, bone morphogenetic protein, hydroxyapatite, and genes coding for the production of bone.