Spinal fusion implant having deployable bone engaging projections

1. An interbody spinal fusion implant for implantation at least in part within and across the generally restored height of a disc space between two adjacent vertebral bodies of a human spine, said spinal implant comprising:

a housing having a leading end for insertion first into the disc space, a trailing end opposite said leading end, a mid-longitudinal axis between said leading end and said trailing end of said horsing, an upper surface adapted to contact one of the adjacent vertebral bodies, a lower surface opposite said upper surface adapted to contact another one of the adjacent vertebral bodies, a height between said upper and lower surfaces, and a hollow interior configured to hold bone growth promoting material therein, said upper and lower surfaces each having at least one opening therein in communication with said hollow interior and with each other to permit for the growth of bone from adjacent vertebral body to adjacent vertebral body through said housing, said hollow interior having a maximum width perpendicular to the height and the mid-longitudinal axis of said housing; and

a substantially hollow internal rotatable member configured to be at least in part within said hollow interior of said housing, said rotatable member having a leading end, a trailing end, a mid-longitudinal axis between said leading end and said trailing end of said rotatable member, a top, a bottom, and an open interior between said top and said bottom, each of said top and said bottom of said rotatable member including at least one bone engaging projection adapted to penetrably engage the bone of the adjacent vertebral bodies by rotating said bone engaging projection about the mid-longitudinal axis of said rotatable member, said top and said bottom including at least one aperture therein in communication with said open interior of said rotatable member and with each other to permit for the growth of bane from vertebral body to vertebral body therethrough, said rotatable member being adapted to rotate at least in part within said hollow interior of said housing between a retracted position and a deployed position, said bone engaging projections extending through said upper and lower surfaces of said housing so as to penetrably engage the bone of the adjacent vertebral bodies when in the deployed position, said rotatable member having a first dimension measured from one of said bone engaging projections on said top to the mid-longitudinal axis along a line perpendicular to the mid-longitudinal axis and a second dimension measured from one of said bone engaging projections on said bottom to the mid-longitudinal axis along a line perpendicular to the mid-longitudinal axis, the sum of said first and second dimensions being greater than the maximum width of said hollow interior of said housing.

2. The implant of claim 1 , wherein said bone engaging projections are fully contained within said hollow interior of said housing when in the retracted position.

3. The implant of claim 1 , wherein said bone engaging projections have a leading edge, when in the deployed position said leading edge of at least two of said bone engaging projections on said top and said bottom of said rotatable member, respectively, are on opposite sides of a plane aligned with the mid-longitudinal axis of said rotational member and passing through said top and said bottom of said rotatable member.

4. The implant of claim 1 , wherein said bone engaging projections have a leading edge, when in the deployed position said leading edge of at least two of said bone engaging projections on said top and said bottom of said rotatable member, respectively, are oriented in an over-center position.

5. The implant of claim 1 , wherein at least one of said bone engaging projections has a base portion extending from said rotatable member and terminating in an upper portion having a length and width, said upper portion having a width that is greater than the width of said base portion.

6. The implant of claim 5 , wherein at least a portion of said at least one bone engaging projection has at least one of a generally T-shaped, C-shaped, V-shaped, W-shaped, and Y-shaped configuration.

7. The implant of claim 5 , wherein said upper portion of said bone engaging projection has a leading edge, a trailing edge, end a thickness that increases at least in part in a direction away from said leading edge along at least a portion of said length of said upper portion.

8. The implant of claim 5 , wherein said upper portion of said bone engaging projection has a decreased distance from said housing proximate said trailing edge when said bone engaging projections are in the deployed position.

9. The implant of claim 5 , wherein said bone engaging projection has a lower portion opposite said upper portion, said upper portion having an arc of radius and said lower portion having an arc of radius that is less than the arc of radius of said upper portion.

10. The implant of claim 5 , wherein said base portion of said at least one bone engaging projection has a leading edge that is at least in part curved.

11. The implant of claim 5 , wherein said upper portion of said at least one bone engaging projection has a leading edge that is at least in part tapered.

12. The implant of claim 5 , further comprising at least one bone engaging projection receiving opening in said upper and lower surfaces of said housing having a configuration generally corresponding to the configuration of said at least one bone engaging projection.

13. The implant of claim 12 , wherein at least one of said bone engaging projection receiving openings in said upper and said lower surfaces of said housing are slots.

14. The implant of claim 13 , wherein at least one of said slots is adapted to contact one of said bone engaging projection.

15. The implant of claim 12 , wherein said bone engaging projection receiving openings also permit for the growth of bone therethrough.

16. The implant of claim 1 , wherein at least two of said bone engaging projections on said top and said bottom of said rotatable member, respectively, are radially offset along the mid-longitudinal axis of said rotatable member.

17. The implant of claim 1 , wherein at least two of said bone engaging projections on said top and said bottom of said rotatable member, respectively, are diametrically opposed along the mid-longitudinal axis of said rotatable member.

18. The implant of claim 1 , wherein at least one of said bone engaging projections has a sharp leading edge adapted to cut into bone.

19. The implant of claim 1 , wherein at least one of said bone engaging projections is a blade.

20. The implant of claim 1 , wherein at least a portion of said bone engaging projections are oriented transverse to the mid-longitudinal axis of said rotatable member.

21. The implant of claim 1 , wherein at least a portion of said bone engaging projections are oriented parallel to one another.

22. The implant of claim 1 , wherein said rotatable member includes a plurality of said bone engaging projections spaced apart from one another along the longitudinal mid-longitudinal axis of said rotatable member.

23. The implant of claim 1 , wherein said housing and said rotatable member cooperate so as to limit rotation of said rotatable member to no more than 180 degrees.

24. The implant of claim 1 , wherein said housing and said rotatable member cooperate so as to limit rotation of said rotatable member to no more than 90 degrees.

25. The implant of claim 1 , wherein said bone engaging projections are fully deployed when said rotatable member is rotated less than 180 degrees.

26. The implant of claim 1 , wherein said bone engaging projections are fully deployed when said rotatable member is rotated less than 360 degrees.

27. The implant of claim 1 , wherein at least one of said leading and said trailing ends of said rotatable member is open.

28. The implant of claim 1 , wherein said trailing end of said rotatable member is configured to cooperatively engage an insertion instrument.

29. The implant of claim 1 , wherein said trailing end of said housing is configured to cooperatively engage an insertion instrument.

30. The implant of claim 29 , wherein said trailing end of said rotatable member is adapted to cooperatively engage an instrument for rotating said rotatable member.

31. The implant of claim 1 , wherein said rotatable member is at least in part cylindrical.

32. The implant of claim 31 , wherein said rotatable member has a root diameter that remains within said housing when in the deployed position.

33. The implant of claim 1 , wherein said rotatable member is at least in part frustoconical.

34. The implant of claim 1 , wherein at least a portion of said apertures of said rotatable member when in said deployed position are configured to generally align with at least a portion of said openings of said housing to allow bone to grow from adjacent vertebral body to adjacent vertebral body through housing implant and through said rotatable member.

35. The implant of claim 1 , wherein said at least one opening in each of said upper and lower surfaces of said housing form windows.

36. The implant of claim 35 , wherein said rotatable member is exposed to the adjacent vertebral bodies through said windows.

37. The implant of claim 35 , wherein said rotatable member projects at least in part through said windows to contact the adjacent vertebral bodies.

38. The implant of claim 35 , wherein said housing is configured to be opened to receive said rotatable member therein and closed to hold said rotatable member at least in part within said housing.

39. The implant of claim 1 , wherein said housing has a transverse cross section that is at least in part generally rectangular along at least a portion of the mid-longitudinal axis of said housing.

40. The implant of claim 1 , wherein said housing has a transverse cross section that is at least in part generally square along at least a portion of the mid-longitudinal axis of said housing.

41. The implant of claim 1 , further comprising at least one arcuate portion in said upper and lower surfaces of said housing, respectively.

42. The implant of claim 41 , wherein said at least one arcuate portion is along at least a portion of mid-longitudinal axis of said implant.

43. The implant of claim 41 , wherein at least two of said arcuate portions are generally located side by side to one another.

44. The implant of claim 1 , wherein at least one of said upper and said lower surfaces of said housing is at least in part non-arcuate.

45. The implant of claim 44 , wherein at least onto of said upper and said lower surfaces of said housing is at least in part arcuate.

46. The implant of claim 1 , wherein said upper and lower surfaces of said housing are at least in part parallel to each other in at least one plane.

47. The implant of claim 1 , wherein said upper and lower surfaces of said housing are at least in part convergent.

48. The implant of claim 1 , wherein said upper and lower surfaces of said housing are at least in part angled to each other.

49. The implant of claim 1 , wherein at least one of aid leading and said trailing ends of said housing includes at least one opening.

50. The implant of claim 49 , wherein said at least one opening of at least one of said leading and said trailing ends of said housing is configured to permit bone growth therethrough.

51. The implant of claim 1 , wherein at least one of said leading and said trailing ends of said housing is open to permit for loading of bone growth promoting material into at least one of said hollow interior of said housing and said open interior of said rotatable member.

52. The implant of claim 51 , further comprising an end cap for closing said open end of said housing.

53. The implant of claim 1 , wherein at least one of said leading and said trailing ends of said housing is configured to permit said rotatable member to be inserted at least in part within said hollow interior of said housing.

54. The implant of claim 53 , wherein said housing is separable into at least two portions to permit the placement of said rotatable member into said open interior of said housing.

55. The implant of claim 1 , further comprising at least two bone engaging projection receiving openings in said upper and said lower surfaces of said housing configured to permit only for the passage of said bone engaging projections therethrough.

56. The implant of claim 55 , wherein at least one of said bone engaging projection receiving openings in said upper and said lower surfaces of said housing are slots.

57. The implant of claim 56 , wherein at least one of said slots is adapted to contact one of said bone engaging projections.

58. The implant of claim 1 , wherein at least two of said openings in said upper and said lower surfaces of said housing are slots oriented transverse to the mid-longitudinal axis of said implant.

59. The implant of claim 1 , wherein said hollow interior of said housing has an interior surface configured to facilitate rotation of said rotatable member therein.

60. The implant of claim 1 , wherein said hollow interior of said housing is configured to limit the degree of rotation of said rotatable member within said housing.

61. The implant of claim 1 , wherein said hollow interior of said housing includes at least one abutment surface adapted to contact a portion of said rotatable member to limit the rotation of said rotatable member.

62. The implant of claim 1 , wherein said leading end of said housing is tapered to facilitate insertion of said implant into the disc space.

63. The implant of claim 1 , wherein said implant has a width that is greater than the height of said implant.

64. The implant of claim 1 , wherein said implant has a height of said implant is greater than the width of said implant.

65. The implant of claim 1 , wherein said implant has a width that is greater than one-half of the transverse width of the disc space into which said implant is adapted to be inserted.

66. The implant of claim 1 , wherein said implant has a width that is less than one-half of the transverse width of the disc space into which said implant is adapted to be inserted to permit at least two of said implants to be implanted into the disc space.

67. The implant of claim 1 , wherein said implant comprises at least in part of one of bone and bone growth promoting material.

68. The implant of claim 67 , wherein said bone growth promoting material is selected from one of bone, bone derived products, demineralized bone matrix, ossifying proteins, bone morphogenetic protein, hydroxyapatite, and genes coding for the production of bone.

69. The implant of claim 1 , in combination with a bone growth promoting material.

70. The implant of claim 69 , wherein said bone growth promoting material is selected from one of bone, bone derived products, demineralized bone matrix, ossifying proteins, bone morphogenetic protein, hydroxyapatite, and genes coding for the production of bone.

71. The implant of claim 1 , wherein said implant is treated with a bone growth promoting substance.

72. The implant of claim 1 , wherein said implant comprises at least one of the following materials: metal, titanium, plastic, and ceramic appropriate for implantation in the human body.

73. The implant of claim 1 , wherein said implant is at least in part resorbable.

74. The implant of claim 1 , wherein said implant is formed of a porous material.

75. The implant of claim 1 , in combination with a chemical substance adapted to inhibit scar formation.

76. The implant of claim 1 , in combination with an antimicrobial material.

77. The implant of claim 1 , wherein said hollow interior of said housing is a chamber for holding bone growth promoting material.

78. The implant of claim 1 , wherein each of said upper and lower surfaces is substantially smooth.

79. The implant of claim 1 , wherein said implant is configured to be pushed into the disc space.

80. The implant of claim 1 , wherein said implant is adapted to be inserted into the disc space without any element of rotation.

81. The implant of claim 1 , wherein said bone engaging projections are non-threaded.

82. The implant of claim 1 , in combination with a guard having a passage for providing protected access to the disc space.

83. The combination of claim 82 , further in combination with a bone removal device having a portion sized for movement through said passage for forming through said guard an implantation space at least in part across the surgically corrected height of the disc space.

84. The combination of claim 83 , wherein said bone removal device is one of a drill, a trephine, a reamer, and a burr.

85. The implant of claim 1 , in combination with a distractor adapted to urge apart the adjacent vertebral bodies.

86. The implant of claim 1 , wherein a cross section of said rotatable member that is transverse to the mid-longitudinal axis of said rotatable member includes a pair of opposed corners connected by a first diagonal and a pair of opposed arcs connected by a second diagonal, the first and second diagonals being oriented generally 90 degrees relative to one another.

87. The implant of claim 86 , wherein said pair of opposed arcs are each of the same radius.

88. The implant of claim 86 , wherein said pair of opposed corners form a 90 degree angle.

89. The implant of claim 1 , wherein at least one of said bone engaging projections includes two sides converging to form a vertex.

90. The implant of claim 89 , wherein said vertex is generally 90 degrees.

91. The implant of claim 1 , wherein two of said bone engaging projections are generally diagonal to one another in a plane transverse to the mid-longitudinal axis of said rotatable member when said rotatable member is in the retracted position.

92. The implant of claim 1 , wherein said rotatable member has a maximum height transverse to the mid-longitudinal axis and a maximum width transverse to the maximum height and the mid-longitudinal axis, the maximum width being generally equal to the maximum height in the retracted position.

93. The implant of claim 1 , wherein said housing has a maximum interior cross sectional dimension transverse to the mid-longitudinal axis of said housing, said rotatable member having a single maximum dimension perpendicular to the mid-longitudinal axis generally corresponding to the maximum interior cross sectional dimension of said housing.

94. The implant of claim 1 , wherein said housing induces opposite sides between said upper and lower surfaces and between said leading and trailing ends, at least one of said upper and lower surfaces of said housing forming a right angle with at least one of said opposite sides.

95. The implant of claim 1 , wherein said upper and lower surfaces are generally non-arcuate from side to side.

96. An interbody spinal fusion implant for implantation at least in part within and across the generally restored height of a disc space between two adjacent vertebral bodies of a human spine, said spiral implant comprising:

a housing having a leading end for insertion first into the disc space, a trailing end opposite said leading end, a mid-longitudinal axis between said leading end and said trailing end of said housing, an upper surface adapted to contact one of the adjacent vertebral bodies, a lower surface adapted to contact another one of the adjacent vertebral bodies, a height between said upper and lower surfaces, and a hollow interior configure to hold bone growth promoting material therein, said upper and lower surfaces; each having at least one opening therein in communication with said hollow interior and with each other to permit for the growth of bone from adjacent vertebral body to adjacent vertebral body through said housing, said hollow interior having a maximum width perpendicular to the height and the mid-longitudinal axis of said housing; and

an internal rotatable member configured to be at least in part within said hollow interior of said housing, said rotatable member having a leading end, a trailing end, a mid-longitudinal axis between said leading end and said trailing end of said rotatable member, a top, and a bottom, each of said top and said bottom of said rotatable member including a plurality of bone engaging projections spaced apart from one another along the mid-longitudinal axis of said rotatable member, each of said top and said bottom of said rotatable member including at least one aperture therein to permit or the growth of bone from vertebral body to vertebral body through said rotatable member, said bone engaging projections adapted to penetrably engage the bone of the adjacent vertebral bodies by rotating said bone engaging projections about the longitudinal mid-longitudinal axis of said rotatable member, said rotatable member being adapted to rotate within said hollow interior of said housing between a retracted position and a deployed position, said bone engaging projections extending through said upper and lower surfaces of said housing so as to penetrably engage the bone of the adjacent vertebral bodies when in the deployed position, said rotatable member having a first dimension measured from one of said bone engaging projections on said top to the mid-longitudinal axis along a line perpendicular to the mid-longitudinal axis and a second dimension measured from one of said bone engaging projections on said bottom to the mid-longitudinal axis along a line perpendicular to the mid-longitudinal axis, the sum of said first and second dimensions being greater than the maximum width of said hollow interior of said housing.

97. The implant of claim 96 , wherein said bone engaging projections are fully contained within said hollow interior of said housing when in the retracted position.

98. The implant of claim 96 , wherein said bone engaging projections have a leading edge, when in the deployed position said leading edge of at least two of said bone engaging projections on said top and said bottom of said rotatable member, respectively, are on opposite sides of a plane aligned with the longitudinal mid-longitudinal axis of said rotational member and passing through said top and said bottom of said rotatable member.

99. The implant of claim 96 , wherein said bone engaging projections have a leading edge, when in the deployed position said leading edge of at least two of said bone engaging projections on said top and said bottom of said rotatable member, respectively, are oriented in an over-center position.

100. The implant of claim 96 , wherein at least two of said bone engaging projections on said top and said bottom of said rotatable member, respectively, are radially offset along the longitudinal mid-longitudinal axis of said rotatable member.

101. The implant of claim 96 , wherein at least two of said bone engaging projections on said top and said bottom of said rotatable member, respectively, are diametrically opposed along the mid-longitudinal axis of said rotatable member.

102. The implant of claim 96 , wherein at least one of said bone engaging projections has a sharp leading edge adapted to cut into none.

103. The implant of claim 96 , wherein said bone engaging projections are fully deployed when said rotatable member is rotated less than 180 degrees.

104. The implant of claim 96 , wherein said bone engaging projections are fully deployed when said rotatable member is rotated less than 360 degrees.

105. The implant of claim 96 , wherein said rotatable member is at least in part cylindrical.

106. The implant of claim 105 , wherein said rotatable member has a root diameter that remains within said housing when in the deployed position.

107. The implant of claim 96 , wherein said rotatable member is at least in part frustoconical.

108. The implant of claim 96 wherein at least a portion of said apertures of said rotatable member when in said deployed position are configured to generally align with at least a portion of said openings of said housing to allow bone to grow from adjacent vertebral body to adjacent vertebral body through said housing and through said rotatable member.

109. The implant of claim 96 , wherein said at least one opening in each of said upper and lower surfaces of said housing form windows.

110. The implant of claim 96 , wherein said housing has a transverse cross section that is at least in part generally rectangular along at least a portion of the mid-longitudinal axis of said housing.

111. The implant of claim 96 , wherein said housing has a transverse cross section that is at least in part generally square along at least a portion of the mid-longitudinal axis of said housing.

112. The implant of claim 96 , further comprising at least one arcuate portion in said upper and lower surfaces of said housing, respectively.

113. The implant of claim 112 , wherein said at least one arcuate portion is along at least a portion of mid-longitudinal axis of said implant.

114. The implant of claim 112 , wherein at least two of said arcuate portions are generally located side by side to one another.

115. The implant of claim 96 , wherein at least one of said upper and said lower surfaces of said housing is at least in part non-arcuate.

116. The implant of claim 115 , wherein at least one of said upper and said lower surfaces of said housing is at least in part arcuate.

117. The implant of claim 96 , wherein said upper and lower surfaces of said housing are at least in part convergent.

118. The implant of claim 96 , wherein said housing is separable into at least two portions to permit the placement of said rotatable member into said open interior of said housing.

119. The implant of claim 96 , wherein said implant comprises at least in part of one of bone and bone growth promoting material.

120. The implant of claim 119 , wherein said bone growth promoting material is selected from one of bone, bone derived products, demineralized bone matrix, ossifying proteins, bone morphogenetic protein, hydroxyapatite, and genes coding for the production of bone.

121. The implant of claim 96 , in combination with a bone growth promoting material.

122. The implant of claim 121 , wherein said bone growth promoting material is selected from one of bone, bone derived products, demineralized bone matrix, ossifying proteins, bone morphogenetic protein, hydroxyapatite, and genes coding for the production of bone.

123. The implant of claim 96 , wherein said implant is treated with a bone growth promoting substance.

124. The implant of claim 96 , wherein said implant comprises at least one of the following materials: metal, titanium, plastic, and ceramic appropriate for implantation in the human body.

125. The implant of claim 96 , wherein said implant is at least in part resorbable.

126. The implant of claim 96 , wherein said implant is formed of a porous material.

127. The implant of claim 96 , in combination with a chemical substance adapted to inhibit scar formation.

128. The implant of claim 96 , in combination with an antimicrobial material.

129. The implant of claim 96 , wherein said hollow interior of said housing is a chamber for holding bone growth promoting material.

130. The implant of claim 96 , wherein at least one of said upper and lower surfaces of said housing is substantially smooth.

131. The implant of claim 96 , wherein each of said upper and lower surfaces is substantially smooth.

132. The implant of claim 96 , wherein said implant is configured to be pushed into the disc space.

133. The implant of claim 96 , wherein said implant is adapted to be inserted into the disc space without any element of rotation.

134. The implant of claim 96 , wherein said bone engaging projections are non-threaded.

135. The implant of claim 96 , in combination with a guard having a passage for providing protected access to the disc space.

136. The combination of claim 135 , further in combination with a bone removal device having a portion sized for movement through said passage for forming through said guard an implantation space at least in part across the surgically corrected height of the disc space.

137. The combination of claim 136 , wherein said bone removal device is one of a drill, a trephine, a reamer, and a burr.

138. The implant of claim 96 , in combination with a distractor adapted to urge apart the adjacent vertebral bodies.

139. The implant of claim 1 , wherein at least one of said upper and lower surfaces of said housing is substantially smooth.

140. An interbody spinal fusion for implantation at least in part within and across the generally restored height of a disc space between two adjacent vertebral bodies of a human spine, said spinal implant comprising:

a housing having a leading end for insertion first into the disc space, a trailing end opposite said leading end, a mid-longitudinal axis between said leading end and said trailing end of said housing, an upper surface adapted to contact one of the adjacent vertebral bodies, a lower surface opposite said upper surface adapted to contact another one of the adjacent vertebral bodies, and a hollow interior configured to hold bone growth promoting material therein, said upper and lower surfaces each having at least one opening therein in communication with said hollow interior and with each other to permit for the growth of bone from adjacent vertebral body to adjacent vertebral body through said housing; and

a substantially hollow internal rotatable member configured to be at least in part within said hollow interior of said housing, said rotatable member having a leading end, a trailing end, a mid-longitudinal axis between said leading end and said trailing end of said rotatable member, a top, a bottom, and an open interior between said top and said bottom, each of said top and said bottom of said rotatable member including at least one bone engaging projection adapted to penetrably engage the bone of the adjacent vertebral bodies by rotating said bone engaging projection about the mid-longitudinal axis of said rotatable member, said top and said bottom including at least one aperture therein in communication with said open interior of said rotatable member and with each other to permit for the growth of bone from vertebral body to vertebral body therethrough, said rotatable member being adapted to rotate at least in part within said hollow interior of said housing between a retracted position and a deployed position, said bone engaging projections extending through said upper and lower surfaces of said housing so as to penetrably engage the bone of the adjacent vertebral bodies when in the deployed position, at least a portion of said apertures of said rotatable member when in said deployed position being configured to generally align with at least a portion of said openings of said housing to allow bone to grow from adjacent vertebral body to adjacent vertebral body through housing implant and through said rotatable member.

141. The implant of claim 140 , wherein said bone engaging projections are adapted to penetrably engage the bone of the adjacent vertebral bodies by rotating said bone engaging projections about the mid-longitudinal axis of said rotatable member.

142. The implant of claim 140 , wherein said at least one bone engaging projection of each of said top and said bottom includes a plurality of bone engaging projections spaced apart from one another along the mid-longitudinal axis of said rotatable member.

143. The implant of claim 140 , wherein said bone engaging projections are fully contained within said hollow interior of said housing when in the retracted position.

144. The implant of claim 140 , wherein at least one of said bone engaging projections has a base portion extending from said rotatable member and terminating in an upper portion having a length and width, said upper portion having a width that is greater than the width of said base portion.

145. The implant of claim 140 , wherein at least one of said bone engaging projections has a sharp leading edge adapted to cut into bone.

146. The implant of claim 140 , wherein at least one of said bone engaging projections is a blade.

147. The implant of claim 140 , wherein said housing and said rotatable member cooperate so as to limit rotation of said rotatable member to no more than 180 degrees.

148. The implant of claim 140 , wherein said rotatable member is at least in part frustoconical.

149. The implant of claim 140 , wherein said housing is configured to be opened to receive said rotatable member therein and closed to hold said rotatable member at least in part within said housing.

150. The implant of claim 140 , wherein at least one of said leading and said trailing ends of said housing is configured to permit said rotatable member to be inserted at least in part within said hollow interior of said housing.

151. The implant of claim 140 , wherein said leading end of said housing is tapered to facilitate insertion of said implant into the disc space.

152. The implant of claim 140 , wherein said implant having a width that is less than one-half of the transverse width of the disc space into which said implant is adapted to be inserted to permit at least two of said implants to be implanted into the disc space.

153. The implant of claim 140 , in combination with a bone growth promoting material.

154. The implant of claim 153 , wherein said bone growth promoting material is selected from one of bone, bone derived products, demineralized bone matrix, ossifying proteins, bone morphogenetic protein, hydroxyapatite, and genes coding for the production of bone.

155. The implant of claim 140 , wherein said implant comprises at least one of the following materials: metal, titanium, plastic, and ceramic appropriate for implantation in the human body.

156. The implant of claim 140 , wherein said implant is at least in part resorbable.

157. The implant of claim 140 , in combination with a chemical substance adapted to inhibit scar formation.

158. The implant of claim 140 , in combination with an antimicrobial material.

159. The implant of claim 140 , wherein said implant is configured to be pushed into the disc space.

160. The implant of claim 140 , in combination with a guard having a passage for providing protected access to the disc space.

161. The combination of claim 160 , further in combination with a bone removal device having a portion sized for movement through said passage for forming through said guard an implantation space at least in part across the surgically corrected height of the disc space.

162. The implant of claim 140 , in combination with a distractor adapted to urge apart the adjacent vertebral bodies.

163. The implant of claim 140 , wherein said upper and lower surfaces are generally non-arcuate from side to side.

164. An interbody spinal fusion for implantation at least in part within and across the generally restored height of a disc space between two adjacent vertebral bodies of a human spine, said spinal implant comprising:

a housing having a leading end for insertion first into the disc space, a trailing end opposite said leading end, a mid-longitudinal axis between said leading end and said trailing end of said housing, an upper surface adapted to contact one of the adjacent vertebral bodies, a lower surface opposite said upper surface adapted to contact another one of the adjacent vertebral bodies, and a hollow interior configured to hold bone growth promoting material therein, said upper and lower surfaces each having at least one opening therein in communication with said hollow interior and with each other to permit for the growth of bone from adjacent vertebral body to adjacent vertebral body through said housing, said housing having a transverse cross section that is at least in part generally square along at least a portion of the mid-longitudinal axis of said housing; and

a substantially hollow internal rotatable member configured to be at least in part within said hollow interior of said housing, said rotatable member having a leading end, a trailing end, a mid-longitudinal axis between said leading end and said trailing end of said rotatable member, a top, a bottom, and an open interior between said top and said bottom, each of said top and said bottom of said rotatable member including at least one bone engaging projection adapted to penetrably engage the bone of the adjacent vertebral bodies by rotating said bone engaging projection about the mid-longitudinal axis of said rotatable member, said top and said bottom including at least one aperture therein in communication with said open interior of said rotatable member and with each other to permit for the growth of bone from vertebral body to vertebral body therethrough, said rotatable member being adapted to rotate at least in part within said hollow interior of said housing between a retracted position and a deployed position, said bone engaging projections extending through said upper and lower surfaces of said housing so as to penetrably engage the bone of the adjacent vertebral bodies when in the deployed position.

165. The implant of claim 164 , wherein said bone engaging projections are adapted to penetrably engage the bone of the adjacent vertebral bodies by rotating said bone engaging projections about the mid-longitudinal axis of said rotatable member.

166. The implant of claim 164 , wherein said at least one bone engaging projection of each of said top and said bottom includes a plurality of bone engaging projections spaced apart from one another along the mid-longitudinal axis of said rotatable member.

167. The implant of claim 164 , wherein said bone engaging projections are fully contained within said hollow interior of said housing when in the retracted position.

168. The implant of claim 164 , wherein at least one of said bone engaging projections has a base portion extending from said rotatable member and terminating in an upper portion having a length and width, said upper portion having a width that is greater than the width of said base portion.

169. The implant of claim 164 , wherein at least one of said bone engaging projections has a sharp leading edge adapted to cut into bone.

170. The implant of claim 164 , wherein at least one of said bone engaging projections is a blade.

171. The implant of claim 164 , wherein said housing and said rotatable member cooperate so as to limit rotation of said rotatable member to no more than 180 degrees.

172. The implant of claim 164 , wherein said rotatable member is at least in part frustoconical.

173. The implant of claim 164 , wherein said housing is configured to be opened to receive said rotatable member therein and dosed to hold said rotatable member at least in part within said housing.

174. The implant of claim 164 , wherein at least one of said leading and said trailing ends of said housing is configured to permit said rotatable member to be inserted at least in part within said hollow interior of said housing.

175. The implant of claim 164 , wherein said leading end of said housing is tapered to facilitate insertion of said implant into the disc space.

176. The implant of claim 164 , wherein said implant has; a width that is less than one-half of the transverse width of the disc space into which said implant is adapted to be inserted to permit at least two of said implants to be implanted into the disc space.

177. The implant of claim 164 , in combination with a bone growth promoting material.

178. The implant of claim 177 , wherein said bone growth promoting material is selected from one of bone, bone derived products, demineralized bone matrix, ossifying proteins, bone morphogenetic protein, hydroxyapatite, and genes coding for the production of bone.

179. The implant of claim 178 , wherein said implant comprises at least one of the following materials: metal, titanium, plastic, and ceramic appropriate for implantation in the human body.

180. The implant of claim 164 , wherein said implant is at least in part resorbable.

181. The implant of claim 164 , in combination with a chemical substance adapted to inhibit scar formation.

182. The implant of claim 164 , in combination with an antimicrobial material.

183. The implant of claim 164 , wherein said implant is configured to be pushed into the disc space.

184. The implant of claim 164 . In combination with a guard having a passage for providing protected access to the disc space.

185. The combination of claim 184 , further in combination with a bone removal device having a portion sized for movement through said passage for forming through said guard an implantation space at least in part across the surgically corrected height of the disc space.

186. The implant of claim 164 , in combination with a distractor adapted to urge apart the adjacent vertebral bodies.

187. The implant of claim 164 , wherein said upper and lower surfaces are generally non-arcuate from side to side.

188. An interbody spinal fusion for implantation at least in part within and across the generally restored height of a disc space between two adjacent vertebral bodies of a human spine, said spinal implant comprising:

a housing having a leading end for insertion first into the disc space, a trailing end opposite said leading end, a mid-longitudinal axis between said leading end and said trailing end of said housing, an upper surface adapted to contact one of the adjacent vertebral bodies, a lower surface opposite said upper surface adapted to contact another one of the adjacent vertebral bodies, and a hollow interior configured to hold bone growth promoting material therein, said upper and lower surfaces each having at least one opening therein in communication with said hollow interior and with each other to permit for the growth of bone from adjacent vertebral body to adjacent vertebral body through said housing; and

a substantially hollow internal rotatable member configured to be at least in part within said hollow interior of said housing, said rotatable member having a leading end, a trailing end, a mid-longitudinal axis between said leading end and said trailing end of said rotatable member, a top, a bottom, and an open interior between said top and said bottom, each of said top and said bottom of said rotatable member including at least one bone engaging projection adapted to penetrably engage the bone of the adjacent vertebral bodies by rotating said bone engaging projection about the mid-longitudinal axis of said rotatable member, said top and said bottom including at least one aperture therein in communication with said open interior of said rotatable member and with each other to permit for the growth of bone from vertebral body to vertebral body therethrough, said rotatable member being adapted to rotate at least in part within said hollow interior of said housing between a retracted position and a deployed position, said bone engaging projections extending through said upper and lower surfaces of said housing so as to penetrably engage the bone of the adjacent vertebral bodies when in the deployed position, said hollow interior of said housing being configured to limit the degree of rotation of said rotatable member within said housing.

189. The implant of claim 188 , wherein said hollow interior of said housing includes at least one abutment surface adapted to contact a portion of said rotatable member to limit the rotation of said rotatable member.

190. The implant of claim 188 , wherein said bone engaging projections are adapted to penetrably engage the bone of the adjacent vertebral bodies by rotating said bone engaging projections about the mid-longitudinal axis of said rotatable member.

191. The implant of claim 188 , wherein said at least one bone engaging projection of each of said top and said bottom includes a plurality of bone engaging projections spaced apart from one another along the mid-longitudinal axis of said rotatable member.

192. The implant of claim 188 , wherein said bone engaging projections are fully contained within said hollow interior of said housing when in the retracted position.

193. The implant of claim 188 , wherein at least one of said bone engaging projections has a base portion extending from said rotatable member and terminating in an upper portion having a length and width, said upper portion having a width that is greater than the width of said base portion.

194. The implant of claim 188 , wherein at least one of said bone engaging projections has a sharp leading edge adapted to cut into lone.

195. The implant of claim 188 , wherein at least one of said bone engaging projections is a blade.

196. The implant of claim 188 , wherein said housing and said rotatable member cooperate so as to limit rotation of said rotatable member to no more than 180 degrees.

197. The implant of claim 188 , wherein said rotatable member is at least in part frustoconical.

198. The implant of claim 188 , wherein said housing is configured to be opened to receive said rotatable member therein and configured to hold said rotatable member at least in part within said housing.

199. The implant of claim 188 , wherein at least one of said leading and said trailing ends of said housing is configured to permit said rotatable member to be inserted at least in part within said hollow interior of said housing.

200. The implant of claim 188 , wherein said leading end of said housing is tapered to facilitate insertion, of said implant into the disc space.

201. The implant of claim 188 , wherein said implant has a width that is less than one-half of the transverse width of the disc space into which said implant is adapted to be inserted to permit at least two of said implants to be implanted into the disc space.

202. The implant of claim 188 , in combination with a bone growth promoting material.

203. The implant of claim 202 , wherein said bone growth promoting material is selected from one of bone, bone derived products, demineralized bone matrix, ossifying proteins, bone morphogenetic protein, hydroxyapatite, and genes coding for the production of bone.

204. The implant of claim 188 , wherein said implant comprises at least one of the following materials: metal, titanium, plastic, and ceramic appropriate for implantation in the human body.

205. The implant of claim 188 , wherein said implant is at least in part resorbable.

206. The implant of claim 188 . In combination with a chemical substance adapted to inhibit scar formation.

207. The implant of claim 188 , in combination with an antimicrobial material.

208. The implant of claim 188 , wherein said implant is configured to be pushed into the disc space.

209. The implant of claim 188 , in combination with a guard having a passage for providing protected access to the disc space.

210. The combination of claim 209 , further in combination with a bone removal device having a portion sized for movement through said passage for forming through said guard an implantation space at least in part across the surgically corrected height of the disc space.

211. The implant of claim 188 . In combination with a distractor adapted to urge apart the adjacent vertebral bodies.

212. The implant of claim 188 , wherein said upper and lower surfaces are generally non-arcuate from side to side.