Expandable push-in interbody spinal fusion implant

• US 6,962,606 B2
• Filed: 12/11/2001
• Issued: 11/08/2005
• Est. Priority Date: 02/04/2000
• Status: Expired due to Term

• Current Assignee: Warsaw Orthopedic Incorporated (Medtronic Plc)
• Original Assignee: Warsaw Orthopedic Incorporated (Medtronic Plc)
• Inventors: Michelson, Gary Karlin
• Primary Examiner(s): Barrett, Thomas
• Application Number:
  US10/011,652
• Publication Number:
  US 20020052656A1
• Time in Patent Office: 1,428 Days
• Field of Search: 623 1711- 1716
• 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 2/442 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 2/447 substantially parallelepipedal, e.g. having a rectangular or trapezoidal cross-section
• 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 2002/30143 hexagonal
• CPC Class Codes: A61F 2002/30187 D-shaped or half-disc-shaped
• CPC Class Codes: A61F 2002/30362 with possibility of relative movement between the protrusion and the recess
• CPC Class Codes: A61F 2002/30405 made by screwing complementary threads machined on the parts themselves
• CPC Class Codes: A61F 2002/30471 connected by a hinged linkage mechanism, e.g. of the single-bar or multi-bar linkage type
• 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 2002/30622 Implant for fusing a joint or bone material
• CPC Class Codes: A61F 2002/30624 : Hinged joint, e.g. with transverse axle restricting the movement
• CPC Class Codes: A61F 2002/30736 : Augments or augmentation pieces, e.g. wedges or blocks for bridging a bone defect
• CPC Class Codes: A61F 2002/30774 : internally-threaded
• 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 2002/30904 : 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 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 2310/00293 : 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

A push-in interbody spinal fusion implant having an expandable height.

Claims

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

an upper member having an upper surface adapted for placement toward and into contact with one of the adjacent vertebral bodies from within the disc space, said upper surface being non-arcuate along a substantial portion of the length of said implant, and to remain in said plane while transitioning said upper and lower members from said first position to said second position said upper surface 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 lower surface adapted for placement toward and into contact with the other of the adjacent vertebral bodies from within the disc space, said lower surface being non-arcuate along a substantial portion of the length of said implant, said lower surface having at least one opening adapted to communicate with the other of the adjacent vertebral bodies, said openings of said upper and lower surfaces 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; 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 positions, said blocker being configured to rotate in a plane generally perpendicular to a longitudinal axis of said implant.

2. The push-in implant of claim 1, further comprising a hollow defined between said upper and lower members in communication with said openings in each of said upper and lower surfaces, said hollow being adapted to receive fusion-promoting substances.

3. The push-in implant of claim 2, wherein said hollow has a width that is unobstructed by any mechanism for moving said blocker.

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

5. The push-in implant of claim 1, wherein said implant has a constant width in both the first position and the second position.

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

7. The push-in implant of claim 1, wherein said blocker is located at a predetermined location along the length of said implant and remains at the predetermined location in transitioning said implant from said first position to said second position.

8. 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.

9. 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.

10. 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.

11. 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.

12. 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.

13. The push-in implant of claim 12, wherein each of said upper and lower members have a track configured to permit said blocker to seat therein.

14. The push-in implant of claim 13, 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 in at least the first position.

15. The push-in implant of claim 1, wherein said blocker moves said upper and lower surfaces of said upper and lower members from one of a parallel orientation and an angled orientation relative to one another in the first position to an angled orientation relative to one another in the second position.

16. 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.

17. 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.

18. The push-in implant of claim 17, wherein said expander is located along the length of said implant.

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

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

21. The push-in implant of claim 17, further comprising a hollow defined between said upper and lower members in communication with said openings in each of said upper and lower surfaces, said hollow being adapted to receive fusion-promoting substances said hollow being 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.

22. The push-in implant of claim 17, wherein said expander remains in the same location along the longitudinal axis of the implant when rotated.

23. The push-in implant of claim 17, 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.

24. The push-in implant of claim 17, 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.

25. The push-in implant of claim 17, 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.

26. The push-in implant of claim 17, wherein said expander moves said upper and lower surfaces of said upper and lower members from one of a parallel orientation and an angled orientation relative to one another in the first position to one of a parallel and an angled orientation relative to one another in the second position.

27. The push-in implant of claim 17, wherein each of said upper and lower members are adapted to cooperate with said expander.

28. The push-in implant of claim 27, wherein each of said upper and lower members have a track configured to permit said expander to rotate therein.

29. The push-in implant of claim 28, wherein said tracks permit said expander to move from side to side within said track.

30. The push-in implant of claim 28, wherein said track of said upper member and said track of said lower member are in the same plane.

31. The push-in implant of claim 28, wherein said track of said upper member and said track of said lower member are parallel to one another.

32. The push-in implant of claim 28, 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.

33. The push-in implant of claim 28, wherein said upper and lower members structurally cooperate with said expander so as to keep said expander located within said implant.

34. The push-in implant of claim 28, wherein at least one of said tracks of said upper and lower members has 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.

35. The push-in implant of claim 34, 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.

36. The push-in implant of claim 35, 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.

37. 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.

38. The push-in implant of claim 27, 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 in at least one of the first and second positions.

39. The push-in implant of claim 28, 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.

40. The push-in implant of claim 39, wherein said cooperating surface of said at least one side is a detent and said corresponding cooperating surface of said expander is a projection.

41. The push-in implant of claim 40, 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.

42. The push-in implant of claim 17, wherein said expander has a first height that is the height of said expander when said implant is initially inserted into the spine, said expander having a second height that is 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.

43. The push-in implant of claim 17, 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 pairs of diametrically opposed junctions.

44. The push-in implant of claim 43, wherein said two pairs of diametrically opposed junctions are a pair of diametrically opposed corners and a pair of diametrically opposed arcs.

45. The push-in implant of claim 43, wherein each of said upper and lower surfaces of said expander lie generally in a plane.

46. The push-in implant of claim 43, wherein said upper and lower surfaces of said expander are generally parallel to one another.

47. The push-in implant of claim 43, wherein said side surfaces and said upper and lower surfaces of said expander are oriented to substantially form portions of a parallelogram.

48. The push-in implant of claim 42, 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.

49. The push-in implant of claim 44, wherein said to diametrically opposed arcs are each of the same radius.

50. The push-in implant of claim 49, wherein the distance across said two diametrically opposed arcs generally approximates the distance between said upper and lower surfaces of said expander.

51. The push-in implant of claim 44, wherein said two diametrically opposed corners form a 90-degree angle.

52. The push-in implant of claim 17, wherein said expander has a depth dimension less than that of said first and second height of said expander.

53. The push-in implant of claim 52, wherein said expander has a fixed shape during movement from an initial insertion position to a final deployed position within said implant.

54. The push-in implant of claim 17, 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.

55. The push-in implant of claim 54, wherein said second expander rotates to increase the height of said implant.

56. The push-in implant of claim 54, wherein said second expander is located proximate an end of said implant opposite said end of said implant were said first expander is located.

57. The push-in implant of claim 54, wherein said second expander rotates in a plane perpendicular to the longitudinal axis of said implant to increase the height of said implant.

58. The push-in implant of claim 56, 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.

59. The push-in implant of claim 56, wherein said second expander remains in the same location along the longitudinal axis of the implant when rotated.

60. The push-in implant of claim 54, wherein said second expander is located proximate one of the proximal end and the distal and of said upper and lower members.

61. The push-in implant of claim 60, 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.

62. The push-in implant of claim 60, further comprising at least a second hollow between said upper and lower member located between said second expander and said end of said implant proximate said second expander.

63. The push-in implant of claim 54, wherein each of said upper and lower members have a track within which said second expander rotates.

64. The push-in implant of claim 63, wherein said track is configured to permit said second expander to rotate therein and then to move from side to side within said track.

65. The push-in implant of claim 54, 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.

66. The push-in implant of claim 54, 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.

67. The push-in implant of claim 66, 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.

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

69. The push-in implant of claim 68, wherein said walls are aligned parallel with the longitudinal axis of said implant.

70. The push-in implant of claim 68, wherein said walls are at least in part overlapping.

71. 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.

72. The push-in implant of claim 71, wherein said rotational articulation is at one of said proximal end and said distal end of said upper and lower members opposite said blocker.

73. The push-in implant of claim 71, wherein said rotational articulation allows for expansion.

74. The push-in implant of claim 73, wherein said rotational articulation allows for limited expansion.

75. The push-in implant of claim 71, wherein said rotational articulation is formed by said upper and lower members interdigitating so as to cooperatively engage.

76. The push-in implant of claim 75, wherein said rotational articulation is configured such that engagement occurs when said upper and lower members are substantially perpendicular to one another.

77. The push-in implant of claim 76, 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.

78. 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 upper and lower surfaces of said upper and lower members are separated by at least a portion of said interior wall, which now has an exposed side.

79. The push-in implant of claim 78, wherein said upper and lower members have side walls for engaging each other.

80. The push-in implant of claim 79, wherein said side walls of said upper and lower members are at least partially overlapping walls.

81. The push-in implant of claim 78, wherein said upper and lower surfaces of said upper and lower members form an angular orientation relative to one another when said implant is in the final position.

82. The push-in implant of claim 78, wherein said upper and lower surfaces of said upper and lower members are substantially planar and parallel when said implant is in the initial insertion position.

83. The push-in implant of claim 1, wherein said implant has an interior, at least one of said upper and lower surfaces 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.

84. The push-in implant of claim 83, wherein each of said upper and lower surfaces 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 surfaces respectively.

85. The push-in implant of claim 83, 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.

86. 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.

87. 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.

88. The push-in implant of claim 87, wherein said interior surface of said cap has spaced slots about its circumference to facilitate a snap fit of said cap into said implant.

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

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

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

92. The push-in implant of claim 31, wherein said implant comprises bone.

93. The push-in implant of claim 92, wherein said bone includes cortical bone.

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

95. The push-in implant of claim 94, wherein said bone growth promoting material is selected from one of bone morphogenetic protein, hydroxyapatite, and genes coding for the production of bone.

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

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

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

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

100. The push-in implant of claim 99, wherein said metal includes titanium.

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

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

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

104. 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.

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

106. The push-in implant of claim 105, wherein said bone growth promoting material is selected from one of bone morphogenetic protein, hydroxyapatite, and genes coding for the production of bone.

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

108. 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.

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

110. The push-in implant of claim 1, further comprising at least a portion of a bone-engaging projection adapted for linear insertion formed on the exterior of each of said upper and lower surfaces for penetrably engaging the adjacent vertebral bodies and to facilitate securing said implant into the spine.

111. The push-in implant of claim 110, wherein said bone-engaging projection is select from one of a ratchet, a surface roughening, and a knurling.

112. The push-in implant of claim 1, wherein said upper member has side walls extending from said upper surface toward said lower member.

113. The push-in implant of claim 1, wherein said lower member has side walls extending from said lower surface toward said upper member.

114. The push-in implant of claim 1, wherein said upper member has side walls extending from said upper surface toward said lower member and said lower member has side walls extending from said lower surface toward said upper member.

115. The push-in implant of claim 1, wherein said implant is substantially parallelepiped.

116. The push-in implant of claim 1, wherein said implant has a width configured to be less than one-half the width of the disc space into which said implant is adapted to be inserted.

117. The push-in implant of claim 1, wherein said implant has a width configured to be greater than one-half the width of the disc space into which said implant is adapted to be inserted.

118. The push-in implant of claim 1, wherein said distal ends of said upper and lower members are symmetrical from side to side.

119. The push-in implant of claim 1, wherein said distal ends of said upper and lower members are asymmetrical from side to side.

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

121. The push-in implant of claim 120, wherein said fusion promoting substance includes at least one of bone, bone morphogenetic protein, hydroxyapatite, and genes coding for the production of bone.

122. The push-in implant of claim 1, in combination with a tool for expanding said implant.

123. The combination of claim 122, wherein said tool is one of a spreader and a distractor.

124. The push-in implant of claim 1, in combination with a tool for inserting said implant at least in part into the disc space.

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

an upper member having an upper surface adapted for placement toward and into contact with one of the adjacent vertebral bodies from within the disc space, said upper surface being non-arcuate along a substantial portion of the length of said implant, said upper surface 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 lower surface adapted for placement toward and into contact with the other of the adjacent vertebral bodies from within the disc space, said lower surface being non-arcuate along a substantial portion of the length of said implant, said lower surface having at least one opening adapted to communicate with the other of the adjacent vertebral bodies, said openings of said upper and lower surfaces 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; 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, said first height and said second height being in a plane.

126. The push-in implant of claim 125, further comprising a hollow defined between said upper and lower members in communication with said openings in each of said upper and lower surfaces, 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.

127. The push-in implant of claim 125, wherein said implant has a constant width in both the collapsed height and the increased height.

128. The push-in implant of claim 125, wherein said implant has a width and said expander has a width less than the width of said implant.

129. The push-in implant of claim 125, wherein said implant has a width and said expander has a width less than one half the width of said implant.

130. The push-in implant of claim 125, wherein said implant has side walls and said expander does not contact said side walls when said implant is in the final deployed position.

131. The push-in implant of claim 125, 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.

132. The push-in implant of claim 125, wherein said expander is located along the length of said implant.

133. The push-in implant of claim 125, wherein said expander is located proximate said proximal ends of said upper and lower members.

134. The push-in implant of claim 125, wherein said expander is located proximate said distal ends of said upper and lower members.

135. The push-in implant of claim 125, wherein said expander remains in the same location along the longitudinal axis of the implant when rotated.

136. The push-in implant of claim 125, 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.

137. The push-in implant of claim 125, 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.

138. The push-in implant of claim 125, 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.

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

140. The push-in implant of claim 139, wherein said expander remains in the same location along the longitudinal axis of the implant wherein rotated.

141. The push-in implant of claim 125, wherein said expander moves said upper and lower surfaces of said upper and lower members from a parallel orientation to an angled orientation relative to one another.

142. The push-in implant of claim 125, wherein each of said upper and lower members are adapted to cooperate with said expander.

143. The push-in implant of claim 142, wherein each of said upper and lower members have a track configured to permit said expanded to rotate therein.

144. The push-in implant of claim 143, wherein said tracks permit said expander to move from side to side within said track.

145. The push-in implant of claim 143, wherein said track of said upper member and said track of said lower member are in the same plane.

146. The push-in implant of claim 143, wherein said track of said upper member and said track of said lower member are parallel to one another.

147. The push-in implant of claim 143, 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.

148. The push-in implant of claim 125, wherein said upper and lower members structurally cooperate with said expander so as to keep said expander located within said implant.

149. The push-in implant of claim 143, wherein at least one of said tracks of said upper and lower members has 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.

150. The push-in implant of claim 149, 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.

151. The push-in implant of claim 150, 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.

152. The push-in implant of claim 125, 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.

153. The push-in implant of claim 142, 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.

154. The push-in implant of claim 143, 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 ls a detent and said corresponding cooperating surface of said expander is a projection.

156. The push-in implant of claim 155, 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.

157. The push-in implant of claim 125, 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.

158. The push-in implant of claim 157, wherein said two diametrically opposed junctions are a pair of diametrically opposed corners and a pair of diametrically opposed arcs.

159. The push-in implant of claim 157, wherein each of said upper and lower surfaces lie generally in a plane.

160. The push-in implant of claim 157, wherein said upper and lower surfaces of said expander are generally parallel to one another.

161. The push-in implant of claim 157, wherein said side surfaces and said upper and lower surfaces are oriented to substantially form a parallelogram.

162. The push-in implant of claim 125, 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.

163. The push-in implant of claim 158 wherein said two diametrically opposed arcs are each of the same radius.

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

165. The push-in implant of claim 158, wherein said two diametrically opposed corners form a 90-degree angle.

166. The push-in implant of claim 125, wherein said expander has a depth dimension less than that of said first and second height of said expander.

167. The push-in implant of claim 166, wherein said expander has a fixed shape during movement from an initial insertion position to a final deployed position within said implant.

168. The push-in implant of claim 125, 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.

169. The push-in implant of claim 168, wherein said second expander rotates to increase the height of said implant.

170. The push-in implant of claim 168, wherein said second expander is located proximate an end of said implant opposite said expander.

171. The push-in implant of claim 168, 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.

172. The push-in implant of claim 170, 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.

173. The push-in implant of claim 170, wherein said second expander remains in the same location along the longitudinal axis of the implant when rotated.

174. The push-in implant of claim 168, wherein said second expander is located proximate one of the proximal end and the distal and of said upper and lower members.

175. The push-in implant of claim 174, 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.

176. The push-in implant of claim 174, 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.

177. The push-in implant of claim 168, wherein each of said upper and lower members have a track within which said second expander rotates.

178. The push-in implant of claim 177, wherein said track is configured to permit said second expander to rotate therein and then to move from side to side within said track.

179. The push-in implant of claim 168, 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.

180. The push-in implant of claim 168, 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.

181. The push-in implant of claim 180, 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.

182. The push-in implant of claim 125, wherein said upper and lower members have walls contacting one another.

183. The push-in implant of claim 182, wherein said walls are aligned parallel with the longitudinal axis of said implant.

184. The push-in implant of claim 182, wherein said walls are at least in part overlapping.

185. The push-in implant of claim 125, 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.

186. The push-in implant of claim 185, wherein said rotational articulation is at one of said proximal end and said distal end of said upper and lower members opposite said expander.

187. The push-in implant of claim 185, wherein said rotational articulation allows for expansion.

188. The push-in implant of claim 187, wherein said rotational articulation allows for limited expansion.

189. The push-in implant of claims 185, wherein said rotational articulation is formed by said upper and lower members interdigitating so as to cooperatively engage.

190. The push-in implant of claim 189, wherein said rotational articulation is configured such that engagement occurs when said upper and lower members are substantially perpendicular to one another.

191. The push-in implant of claim 190, 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.

192. The push-in implant of claim 125, 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 upper and lower surfaces of said upper and lower members are separated by at least a portion of said interior wall, which now has an exposed side.

193. The push-in implant of claim 192, wherein said tipper and lower members have side walls for engaging each other.

194. The push-in implant of claim 193, wherein said side walls of said upper and lower members are at least partially overlapping wall.

195. The push-in implant of claim 192, wherein said upper and lower surfaces of said upper and lower members form an angular orientation relative to one another when said implant is in the final position.

196. The push-in implant of claim 192, wherein said upper and lower surfaces of said upper and lower members are substantially planar and parallel when said implant is in the initial insertion position.

197. The push-in implant of claim 125, wherein said implant has an interior, at least one of said upper and lower surfaces 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.

198. The push-in implant of claim 197, wherein each of said upper and lower surfaces 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 surfaces respectively.

199. The push-in implant of claim 197, 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.

200. The push-in implant of claim 125, wherein said implant has a side surface when in a final position that is contoured to cooperate with another implant.

201. The push-in implant of claim 125, 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.

202. The push-in implant of claim 201, wherein said interior surface of said cap has spaced slots about its circumference to facilitate a snap fit of said cap into said implant.

203. The push-in implant of claim 125, wherein said implant comprises an artificial material other than bone.

204. The push-in implant of claim 125, wherein said implant is made of an artificial material that is stronger than bone.

205. The push-in implant of claim 125, wherein said implant is made of an artificial material that is harder than bone.

206. The push-in implant of claim 125, wherein said implant comprises bone.

207. The push-in implant of claim 206 wherein said bone includes cortical bone.

208. The push-in implant of claim 125, wherein said implant comprises bone growth promoting material.

209. The push-in implant of claim 208, wherein said bone growth promoting material is selected from one of bone morphogenetic protein, hydroxyapatite, and genes coding for the production of bone.

210. The push-in implant of claim 125, wherein said implant is treated with a bone growth promoting substance.

211. The push-in implant of claim 125, wherein said implant is a source of osteogenesis.

212. The push-in implant of claim 125, wherein said implant is at least in part bioabsorbable.

213. The push-in implant of claim 125, wherein said implant comprises metal.

214. The push-in implant of claim 213, wherein said metal includes titanium.

215. The push-in implant of claim 125, wherein said implant comprises a plastic material.

216. The push-in implant of claim 125, wherein said implant comprises a a ceramic material.

217. The push-in implant of claim 125, wherein said implant is formed of a porous material.

218. The push-in implant of claim 125, 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.

219. The push-in implant of claim 125, wherein said implant has an interior surface and a hollow defined therein, said hollow being capable of containing bone growth promoting material.

220. The push-in implant of claim 219, wherein said bone growth promoting material is selected from one of bone morphogenetic protein, hydroxyapatite, and genes coding for the production of bone.

221. The push-in implant of claim 125, wherein said at least one opening is adapted to retain fusion-promoting materials.

222. The push-in implant of claim 125, wherein at least a portion of said implant is treated to promote bone ingrowth between said implant and said adjacent vertebral bodies.

223. The push-in implant of claim 125, in combination with a chemical substance to inhibit scar formation.

224. The push-in implant of claim 125, further comprising at least a portion of a bone-engaging projection adapted for linear insertion formed on the exterior of each of said upper and lower surfaces for penetrably engaging the adjacent vertebral bodies and to facilitate securing said implant into the spine.

225. The push-in implant of claim 224, wherein said tone-engaging projection is select from one of a ratchet, a surface roughening, and a knurling.

226. The push-in implant of claim 125, wherein said upper member has side walls extending from said upper surface toward said lower member.

227. The push-in implant of claim 125, wherein said lower member has side walls extending from said lower surface toward said upper member.

228. The push-in implant of claim 125, wherein said upper member has side walls extending from said upper surface toward said lower member and said lower member has side walls extending from said lower surface toward said upper member.

229. The push-in implant of claim 125, wherein said implant is substantially parallelepiped.

230. The push-in implant of claim 125, wherein said implant has a width configured to be less than one-half the width of the disc space into which said implant is adapted to be inserted.

231. The push-in implant of claim 125, wherein said implant has a width configured to be greater than one-half the width of the disc space into which said implant is adapted to be inserted.

232. The push-in implant of claim 125, wherein said distal ends of said upper and lower members are symmetrical from side to side.

233. The push-in implant of claim 125, wherein said distal ends of said upper and lower members are asymmetrical from side to side.

234. The push-in implant of claim 125, in combination with a fusion promoting substance.

235. The push-in implant of claim 234, wherein said fusion promoting substance includes at least one of bone, bone morphogenetic protein, hydroxyapatite, and genes coding for the production of bone.

236. The push-in implant of claim 125, in combination with a tool for expanding said implant.

237. The combination of claim 236, wherein said tool is one of a spreader and a distractor.

238. The push-in implant of claim 125, in combination with a tool for inserting said implant at least in part into the disc space.

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

an upper member having an upper surface adapted for placement toward and into contact with one of the adjacent vertebral bodies from within the disc space, said upper surface being non-arcuate along a substantial portion of the length of said implant, said upper surface 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 lower surface adapted for placement toward and into contact with the other of the adjacent vertebral bodies from within the disc space, said lower surface being non-arcuate along a substantial portion of the length of said implant, said lower surface having at least one opening adapted to communicate with the other of the adjacent vertebral bodies, said openings of said upper and lower surfaces 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; 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, said expander being adapted to expand said implant from a first collapsed height to a second expanded height when moved from a first to a second position, each of said upper and lower members being adapted to cooperate with said expander, each of said upper and lower members having a track configured to permit said expander to rotate therein, said tracks permitting said expander to move from side to side within said track.

240. The push-in implant of claim 239, further comprising a hollow defined between said upper and lower members in communication with said openings in each of said upper and lower surfaces, said hollow being adapted to receive fusion-promoting substances.

241. The push-in implant of claim 240, wherein said hollow has a width that is unobstructed by any mechanism for moving said blocker.

242. The push-in implant of claim 239, wherein said implant has a constant width in both the first position and the second position.

243. The push-in implant of claim 239, wherein said blocker is located at a predetermined location along the length of said implant and remains at the predetermined location in transitioning said implant from said first position to said second position.

244. The push-in implant of claim 239, wherein said implant has a width and said blocker has a width less than the width of said implant.

245. The push-in implant of claim 239, wherein said implant has side walls and said blocker does not contact said side walls when said implant is in the final deployed position.

246. The push-in implant of claim 239, 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.

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

248. The push-in implant of claim 239, in combination with a chemical substance to inhibit scar formation.

249. The push-in implant of claim 239, further comprising at least a portion of a bone-engaging projection adapted for linear insertion formed on the exterior of each of said upper and lower surfaces for penetrably engaging the adjacent vertebral bodies and to facilitate securing said implant into the spine.

250. The push-in implant of claim 249, wherein said bone-engaging projection is select from one of a ratchet, a surface roughening, and a knurling.

251. The push-in implant of claim 239, wherein said implant has a width configured to be less than one-half the width of the disc space into which said implant is adapted to be inserted.

252. The push-in implant of claim 239, in combination with a fusion promoting substance.

253. The push-pin 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. The push-in implant of claim 239, in combination with a tool for expanding said implant.

255. The combination of claim 254, wherein said tool is one of a spreader and a distractor.

256. The push-in implant of claim 239, in combination with a tool for inserting said implant at least in part into the disc space.

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

an upper member having an upper surface adapted for placement toward and into contact with one of the adjacent vertebral bodies from within the disc space, said upper surface being non-arcuate along a substantial portion of the length of said implant, said upper surface 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 lower surface adapted for placement toward and into contact with the other of the adjacent vertebral bodies;

from within the disc space, said lower surface being non-arcuate along a substantial portion of the length of said implant, said lower surface having at least one opening adapted to communicate with the other of the adjacent vertebral bodies, said openings of said upper and lower surfaces 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; 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, said expander being adapted to expand said implant from a first collapsed height to a second expanded height when moved from a first to a second position, said expander having 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 of the expander at two pairs of diametrically opposed junctions, one of said pair of diametrically opposed junctions being a pair of diametrically opposed arcs.

258. The push-in implant of claim 257, further comprising a hollow defined between said upper and lower members in communication with said openings in each of said upper and lower surfaces, said hollow being adapted to receive fusion-promoting substances.

259. The push-in implant of claim 258, wherein said hollow has a width that is unobstructed by any mechanism for moving said blocker.

260. The push-in implant of claim 257, wherein said implant has a constant width in both the first position and the second position.

261. The push-in implant of claim 257, wherein said blocker is located at a predetermined location along the length of said implant and remains at the predetermined location in transitioning said implant from said first position to said second position.

262. The push-in implant of claim 257, wherein said implant has a width and said blocker has a width less than the width of said implant.

263. The push-in implant of claim 257, wherein said implant has side walls and said blocker does not contact said side walls when said implant is in the final deployed position.

264. The push-in implant of claim 257, 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.

265. The push-in implant of claim 257, wherein said implant is at least in part bioabsorbable.

266. The push-in implant of claim 257, in combination with a chemical substance to inhibit scar formation.

267. The push-in implant of claim 257, further comprising at least a portion of a bone-engaging projection adapted for linear insertion formed on the exterior of each of said upper and lower surfaces for penetrably engaging the adjacent vertebral bodies and to facilitate securing said implant into the spine.

268. The push-in implant of claim 267, wherein said bone-engaging projection is select from one of a ratchet, a surface roughening, and a knurling.

269. The push-in implant of claim 257, wherein said implant has a width configured to be less than one-half the width of the disc space into which said implant is adapted to be inserted.

270. The push-in implant of claim 257, in combination with a fusion promoting substance.

271. The push-in implant of claim 270, wherein said fusion promoting substance includes at least one of bone, bone morphogenetic protein, hydroxyapatite, and genes coding for the production of bone.

272. The push-in implant of claim 257, in combination with a tool for expanding said implant.

273. The combination of claim 272, wherein said tool is one of a spreader and a distractor.

274. The push-in implant of claim 257, in combination with a tool for inserting said implant at least in part into the disc space.

275. The push-in implant of claim 257, wherein the other of said two pairs of diametrically opposed junctions is a pair of diametrically opposed corners.

276. The push-in implant of claim 257, wherein each of said upper and lower surfaces of said expander lie generally in a plane.

277. The push-in implant of claim 257, wherein said upper and lower surfaces of said expander are generally parallel to one another.

278. The push-in implant of claim 257, wherein said side surfaces and said upper and lower surfaces of said expander are oriented to substantially form portions of a parallelogram.

279. The push-in implant of claim 257, wherein said two diametrically opposed arcs are each of the same radius.

280. The push-in implant of claim 257, wherein the distance across said two diametrically opposed arcs generally approximates the distance between said upper and lower surfaces of said expander.

281. The push-in implant of claim 275, wherein said two diametrically opposed corners form a 90-degree angle.

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

an upper member having an upper surface adapted for placement toward and into contact with one of the adjacent vertebral bodies from within the disc space, said upper surface being non-arcuate along a substantial portion of the length of said implant, said upper surface 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 lower surface adapted for placement toward and into contact with the other of the adjacent vertebral bodies from within the disc space, said lower surface being non-arcuate along a substantial portion of the length of said implant, said lower surface having at least one opening adapted to communicate with the other of the adjacent vertebral bodies, said openings of said upper and lower surfaces 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; 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, said expander being configured to rotate in a plane generally perpendicular to a longitudinal axis of said implant.

283. The push-in implant of claim 282, further comprising a hollow defined between said upper and lower members in communication with said openings in each of said upper and lower surfaces, said hollow being adapted to receive fusion-promoting substances.

284. The push-in implant of claim 283, wherein said hollow has a width that is unobstructed by any mechanism for moving said blocker.

285. The push-in implant of claim 282, wherein said implant has a constant width in both the first position and the second position.

286. The push-in implant of claim 282, wherein said blocker is located at a predetermined location along the length of said implant and remains at the predetermined location in transitioning said implant from said first position to said second position.

287. The push-in implant of claim 282, wherein said implant has a width and said blocker has a width less than the width of said implant.

288. The push-in implant of claim 282, wherein said implant has side walls and said blocker does not contact said side walls when said implant is in the final deployed position.

289. The push-in implant of claim 282, 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.

290. The push-in implant of claim 282, wherein said implant is at least in part bioabsorbable.

291. The push-in implant of claim 282, in combination with a chemical substance to inhibit scar formation.

292. The push-in implant of claim 282, further comprising at least a portion of a bone-engaging projection adapted for linear insertion formed on the exterior of each of said upper and lower surfaces for penetrably engaging the adjacent vertebral bodies and to facilitate securing said implant into the spine.

293. The push-in implant of claim 282, wherein said bone-engaging projection is select from one of a ratchet, a surface roughening, and a knurling.

294. The push-in implant of claim 282, wherein said implant has a width configured to be less than one-half the width of the disc space into which said implant is adapted to be inserted.

295. The push-in implant of claim 282, in combination with a fusion promoting substance.

296. The push-in implant of claim 295, wherein said fusion promoting substance includes at least one of bone, bone morphogenetic protein, hydroxyapatite, and genes coding for the production of bone.

297. The push-in implant of claim 282, in combination with a tool for expanding said implant.

298. The combination of claim 297, wherein said tool is one of a spreader and a distractor.

299. The push-in implant of claim 282, in combination with a tool for inserting said implant at least in part into the disc space.

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

an upper member having an upper surface adapted for placement toward and into contact with one of the adjacent vertebral bodies from within the disc space, said upper surface being non-arcuate along a substantial portion of the length of said implant, said upper surface 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 lower surface adapted for placement toward and into contact with the other of the adjacent vertebral bodies from within the disc space, said lower surface being non-arcuate along a substantial portion of the length of said implant, said lower surface having at least one opening adapted to communicate with the other of the adjacent vertebral bodies, said openings of said upper and lower surfaces 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; 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 being adapted to cooperate with said expander, each of said upper and lower members having a track configured to permit said expander to rotate therein, said tracks permitting said expander to move from side to side within said track.

301. The push-in implant of claim 300, further comprising a hollow defined between said upper and lower members in communication with said openings in each of said upper and lower surfaces, said hollow being adapted to receive fusion-promoting substances.

302. The push-in implant of claim 301, wherein said hollow has a width that is unobstructed by any mechanism for moving said blocker.

303. The push-in implant of claim 300, wherein said implant has a constant width in both the first position and the second position.

304. The push-in implant of claim 300, wherein said blocker is located at a predetermined location along the length of said implant and remains at the predetermined location in transitioning said implant from said first position to said second position.

305. The push-in implant of claim 300, wherein said implant has a width and said blocker has a width less than the width of said implant.

306. The push-in implant of claim 300, wherein said implant has side walls and said blocker does not contact said side walls when said implant is in the final deployed position.

307. The push-in implant of claim 300, 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.

308. The push-in implant of claim 300, wherein said implant is at least in part bioabsorbable.

309. The push-in implant of claim 300, in combination with a chemical substance to inhibit scar formation.

310. The push-in implant of claim 300, further comprising at least a portion of a bone-engaging projection adapted for linear insertion formed on the exterior of each of said upper and lower surfaces for penetrably engaging the adjacent vertebral bodies and to facilitate securing said implant into the spine.

311. The push-in implant of claim 310, wherein said bone-engaging projection is select from one of a ratchet, a surface roughening and a knurling.

312. The push-in implant of claim 300, wherein said implant has a width configured to be less than one-half the width of the disc space into which said implant is adapted to be inserted.

313. The push-in implant of claim 300, in combination with a fusion promoting substance.

314. The push-in implant of claim 313, wherein said fusion promoting substance includes at least one of bone, bone morphogenetic protein, hydroxyapatite, and genes coding for the production of bone.

315. The push-in implant of claim 300, in combination with a tool for expanding said implant.

316. The combination of claim 315, wherein said tool is one of a spreader and a distractor.

317. The push-in implant of claim 300, in combination with a tool for inserting said implant at least in part into the disc space.

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

an upper member having an upper surface adapted for placement toward and into contact with one of the adjacent vertebral bodies from within the disc space, said upper surface being non-arcuate along a substantial portion of the length of said implant, said upper surface 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 lower surface adapted for placement toward and into contact with the other of the adjacent vertebral bodies from within the disc space, said lower surface being non-arcuate along a substantial portion of the length of said implant, said lower surface having at least one opening adapted to communicate with the other of the adjacent vertebral bodies, said openings of said upper and lower surfaces 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; 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, said expander having 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, one of said pair of diametrically opposed junctions being a pair of diametrically opposed arcs.

319. The push-in implant of claim 318, further comprising a hollow defined between said upper and lower members in communication with said openings in each of said upper and lower surfaces, said hollow being adapted to receive fusion-promoting substances.

320. The push-in implant of claim 319, wherein said hollow has a width that is unobstructed by any mechanism for moving said blocker.

321. The push-in implant of claim 318, wherein said implant has a constant width in both the first position and the second position.

322. The push-in implant of claim 318, wherein said blocker is located at a predetermined location along the length of said implant and remains at the predetermined location in transitioning said implant from said first position to said second position.

323. The push-in implant of claim 318, wherein said implant has a width and said blocker has a width less than the width of said implant.

324. The push-in implant of claim 318, wherein said implant has side walls and said blocker does not contact said side walls when said implant is in the final deployed position.

325. The push-in implant of claim 318, 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.

326. The push-in implant of claim 318, wherein said implant is at least in part bioabsorbable.

327. The push-in implant of claim 318, in combination with a chemical substance to inhibit scar formation.

328. The push-in implant of claim 318, further comprising at least a portion of a bone-engaging projection adapted for linear insertion formed on the exterior of each of said upper and lower surfaces for penetrably engaging the adjacent vertebral bodies and to facilitate securing said implant into the spine.

329. The push-in implant of claim 328, wherein said bone-engaging projection is select from one of a ratchet, a surface roughening, and a knurling.

330. The push-in implant of claim 318, wherein said implant has a width configured to be less than one-half the width of the disc space into which said implant is adapted to be inserted.

331. The push-in implant of claim 318, in combination with a fusion promoting substance.

332. The push-in implant of claim 331, wherein said fusion promoting substance includes at least one of bone, bone morphogenetic protein, hydroxyapatite, and genes coding for the production of bone.

333. The push-in implant of claim 318, in combination with a tool for expanding said implant.

334. The combination of claim 333, wherein said tool is tine of a spreader and a distractor.

335. The push-in implant of claim 318, in combination with a tool for inserting said implant at least in part into the disc space.

336. The push-in implant of claim 318, wherein the other of said two pairs of diametrically opposed junctions is a pair of diametrically opposed corners.

337. The push-in implant of claim 318, wherein each of said upper and lower surfaces of said expander lie generally in a plane.

338. The push-in implant of claim 318, wherein said upper and lower surfaces of said expander are generally parallel to one another.

339. The push-in implant of claim 318, wherein said side surfaces and said upper and lower surfaces of said expander are oriented to substantially form portions of a parallelogram.

340. The push-in implant of claim 318, wherein said two diametrically opposed arcs are each of the same radius.

341. The push-in implant of claim 318, wherein the distance across said two diametrically opposed arcs generally approximates the distance between said upper and lower surfaces of said expander.

342. The push-in implant of claim 336, wherein said two diametrically opposed corners form a 90-degree angle.