Artificial spinal fusion implants

• US 6,478,823 B1
• Filed: 05/30/2000
• Issued: 11/12/2002
• Est. Priority Date: 06/28/1988
• Status: Expired due to Term

• Current Assignee: SDGI Holdings Incorporated (Medtronic Plc)
• Original Assignee: Sofamor Danek Holdings, Inc
• Inventors: Michelson, Gary Karlin
• Primary Examiner(s): McDermott, Corrine
• Assistant Examiner(s): BARRETT, THOMAS C
• Application Number:
  US09/580,768
• Time in Patent Office: 896 Days
• Field of Search: 623/17.11, 623/17.16
• US Class Current: 623/17.16
• CPC Class Codes: A61F 2/30744 End caps, e.g. for closing an endoprosthetic cavity
• CPC Class Codes: A61F 2/30767 Special external or bone-contacting surface, e.g. coating for improving bone ingrowth
• CPC Class Codes: A61F 2/44 for the spine, e.g. vertebrae, spinal discs
• CPC Class Codes: A61F 2/442 Intervertebral or spinal discs, e.g. resilient non-disc-shaped intervertebral inflatable pockets A61F2/441; non-disc-shaped intervertebral fusion implants A61F2/4455
• CPC Class Codes: A61F 2/4455 for the fusion of spinal bodies, e.g. intervertebral fusion of adjacent spinal bodies, e.g. fusion cages intervertebral discs A61F2/442
• CPC Class Codes: A61F 2/447 substantially parallelepipedal, e.g. having a rectangular or trapezoidal cross-section
• CPC Class Codes: A61F 2/4611 of spinal prostheses
• CPC Class Codes: A61F 2002/2835 Bone graft implants for filling a bony defect or an endoprosthesis cavity, e.g. by synthetic material or biological material
• CPC Class Codes: A61F 2002/30062 (bio)absorbable, biodegradable, bioerodable, (bio)resorbable, resorptive
• CPC Class Codes: A61F 2002/30143 hexagonal
• CPC Class Codes: A61F 2002/30153 rectangular
• CPC Class Codes: A61F 2002/30158 trapezoidal
• CPC Class Codes: A61F 2002/30261 parallelepipedal
• CPC Class Codes: A61F 2002/3037 Translation along the common longitudinal axis, e.g. piston
• CPC Class Codes: A61F 2002/30398 Sliding
• CPC Class Codes: A61F 2002/30405 made by screwing complementary threads machined on the parts themselves
• CPC Class Codes: A61F 2002/30433 using additional screws, bolts, dowels, rivets or washers e.g. connecting screws
• CPC Class Codes: A61F 2002/30507 using a threaded locking member, e.g. a locking screw or a set screw
• CPC Class Codes: A61F 2002/30523 by means of meshing gear teeth
• CPC Class Codes: A61F 2002/30556 for adjusting thickness
• CPC Class Codes: A61F 2002/30579 : with mechanically expandable devices, e.g. fixation devices
• CPC Class Codes: A61F 2002/30593 : hollow
• CPC Class Codes: A61F 2002/30599 : stackable
• CPC Class Codes: A61F 2002/30604 : modular
• CPC Class Codes: A61F 2002/30774 : internally-threaded
• CPC Class Codes: A61F 2002/30777 : Oblong apertures
• 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 2002/30797 : internally-threaded
• CPC Class Codes: A61F 2002/30836 : knurled
• CPC Class Codes: A61F 2002/30841 : Sharp anchoring protrusions for impaction into the bone, e.g. sharp pins, spikes
• CPC Class Codes: A61F 2002/30843 : Pyramidally-shaped
• CPC Class Codes: A61F 2002/30904 : serrated profile, i.e. saw-toothed
• CPC Class Codes: A61F 2002/3092 : having an open-celled or open-pored structure
• 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 2002/4485 : comprising three or more adjacent spinal implants
• CPC Class Codes: A61F 2002/449 : comprising multiple spinal implants located in different intervertebral spaces or in different vertebrae
• CPC Class Codes: A61F 2002/4627 : with linear motion along or rotating motion about the instrument axis or the implantation direction, e.g. telescopic, along a guiding rod, screwing inside the instrument
• CPC Class Codes: A61F 2002/4629 : connected to the endoprosthesis or implant via a threaded connection
• CPC Class Codes: A61F 2210/0004 : bioabsorbable
• 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 2220/0041 : using additional screws, bolts, dowels or rivets, e.g. connecting screws
• CPC Class Codes: A61F 2230/0017 : Angular shapes
• CPC Class Codes: A61F 2230/0019 : rectangular
• CPC Class Codes: A61F 2230/0026 : trapezoidal
• CPC Class Codes: A61F 2230/0082 : parallelepipedal
• CPC Class Codes: A61F 2250/0009 : for adjusting thickness
• CPC Class Codes: A61F 2250/0063 : Nested prosthetic parts
• CPC Class Codes: A61F 2310/00796 : Coating or prosthesis-covering structure made of a phosphorus-containing compound, e.g. hydroxy(l)apatite
• CPC Class Codes: Y10S 606/907 : Composed of particular material or coated

Abstract

A spinal implant is disclosed which when placed within the spinal disc space stabilizes that spinal segment and materially participates in, and is incorporated in, the ensuing fusion.

Claims

1. An artificial interbody spinal fusion implant for insertion within an implantation space formed across the height of a disc space between vertebral bodies of a human spine, the vertebral bodies having an anterior aspect and a posterior aspect and a depth therebetween, said implant comprising:

a leading end for insertion first into the disc space and a trailing end opposite said leading end, said implant having a length from said leading end to said trailing end;

a top and a bottom between said leading and trailing ends adapted to space apart the adjacent vertebral bodies, said top and said bottom having at least one opening therethrough, said openings being in communication with one another to permit for the growth of bone from adjacent vertebral body to adjacent vertebral body through said implant, said implant having a height from said top to said bottom;

opposite sides between said top and said bottom, and between said leading and trailing ends, said implant having a width from one of said sides to the other of said sides;

the width of said implant being greater than one-half the width of those vertebral bodies that are adjacent the implantation space into which said implant is adapted to be inserted, the height of said implant being less than the width of said implant;

said implant being formed at least in part of a material other than bone; and

said implant being configured to be wholly contained within the perimeter of the adjacent vertebral bodies.

2. The implant of claim 1, wherein said top and said bottom further comprise at least a second opening.

3. The implant of claim 1, wherein at least one of said openings are approximately 1 mm to 3 mm in diameter.

4. The implant of claim 1, wherein at least one of said openings is macroscopic in size.

5. The implant of claim 1, wherein at least one of said openings is micro-sized.

6. The implant of claim 1, wherein at least some of said openings in said top and said bottom form a channel through said implant.

7. The implant of claim 1, wherein said trailing end includes at least one perforation.

8. The implant of claim 1, wherein the junctions of said sides and at least one of said trailing end and said leading end are rounded.

9. The implant of claim 1, wherein said sides are generally parallel to one another.

10. The implant of claim 1, wherein said sides are generally flat.

11. The implant of claim 1, wherein said implant has a width that is approximately 32 mm for use in the lumbar spine.

12. The implant of claim 1, wherein said implant has a generally rectangular cross section along at least a portion of its length.

13. The implant of claim 1, wherein said leading end is at least in part non-linear.

14. The implant of claim 1, wherein at least a portion of said leading end is tapered for facilitating insertion of said implant between the two adjacent vertebral bodies.

15. The implant of claim 1, wherein said leading end is curved.

16. The implant of claim 15, wherein said leading end is convex.

17. The implant of claim 15, wherein said leading end generally conforms to the disc space proximate the posterior aspect of the vertebral bodies.

18. The implant of claim 1, wherein said trailing end is curved.

19. The implant of claim 18, wherein said trailing end is convex.

20. The implant of claim 1, wherein said implant has a length along a mid-longitudinal axis of said implant, said length having a maximum that is less than the posterior to anterior depth of the vertebral body.

21. The implant of claim 1, wherein said implant is adapted for insertion from the posterior aspect of the vertebral bodies.

22. The implant of claim 1, wherein said implant is adapted for insertion from the anterior aspect of the vertebral bodies.

23. The implant of claim 1, wherein said implant is sized to replace a substantial portion of the disc with a single implant.

24. The implant of claim 1, wherein said implant has a height at least as great as the restored height of the disc space.

25. The implant of claim 1, wherein said top and said bottom are generally parallel.

26. The implant of claim 1, further comprising at least one protrusion extending from said top and said bottom for engaging the adjacent vertebral bodies to maintain said implant within the disc space.

27. The implant of claim 26, wherein said protrusion comprises a ridge.

28. The implant of claim 27, wherein said protrusion includes a plurality of ridges and said ridges are facing the same direction to prevent expulsion of said implant in a direction opposite to said same direction.

29. The implant of claim 26, wherein said protrusion comprises a tooth.

30. The implant of claim 26, wherein said protrusion comprises a ratchet.

31. The implant of claim 30, wherein said ratchets are facing the same direction to prevent expulsion of said implant in a direction opposite to said same direction.

32. The implant of claim 1, wherein said top and said bottom have a porous surface.

33. The implant of claim 1, wherein said top and said bottom have a bone ingrowth surface.

34. The implant of claim 1, wherein said implant has an exterior surface that is at least in part porous.

35. The implant of claim 1, wherein said implant material is porous.

36. The implant of claim 1, in combination with a fusion promoting material other than bone.

37. The implant of claim 1, wherein said implant comprises a bone ingrowth material other than bone.

38. The implant of claim 1, further comprising a material that intrinsically participates in the growth of bone from one of the adjacent vertebral bodies to the other of the adjacent vertebral bodies.

39. The implant of claim 1, wherein said implant is treated with a fusion promoting substance.

40. The implant of claim 39, wherein said fusion promoting substance is autogenous bone.

41. The implant of claim 1, wherein said implant material is stronger than bone.

42. The implant of claim 1, further in combination with an osteogenic material.

43. The implant of claim 42, wherein said osteogenic material is a material other than bone.

44. The implant of claim 1, wherein said implant is adapted to be centrally placed within the disc space.

45. An artificial interbody spinal fusion implant for insertion within an implantation space formed across the height of a disc space between vertebral bodies of a human spine, the vertebral bodies having an anterior aspect and a posterior aspect and a depth therebetween, said implant comprising:

a leading end for insertion first into the disc space and a trailing end opposite said leading end, said implant having a length from said leading end to said trailing end;

a top and a bottom between said leading and trailing ends adapted to space apart the adjacent vertebral bodies, said top and said bottom having at least one opening therethrough, said openings being in communication with one another to permit for the growth of bone from adjacent vertebral body to adjacent vertebral body through said implant, each of said top and said bottom having an interior surface, said interior surfaces being spaced apart to define a hollow interior in communication with said openings, said implant having a height from said top to said bottom;

opposite sides between said top and said bottom, and between said leading and trailing ends, said implant having a width from one of said sides to the other of said sides;

the width of said implant being greater than one-half the width of those vertebral bodies that are adjacent the implantation space into which said implant is adapted to be inserted, the height of said implant being less than the width of said implant;

an access opening for accessing said hollow interior;

said implant being formed at least in part of a material other than bone;

said implant being configured to be wholly contained within the perimeter of the adjacent vertebral bodies; and

said implant being adapted to engage a cover for at least in part closing said access opening.

46. The implant of claim 45, wherein said access opening is configured to permit insertion of osteogenic material into said hollow interior.

47. The implant of claim 46, wherein said osteogenic material includes a fusion promoting material.

48. The implant of claim 46, wherein said osteogenic material is bone.

49. The implant of claim 46, wherein said osteogenic material is a material other than bone.

50. The implant of claim 45, further comprising a cover adapted to cooperatively engage said access opening.

51. The implant of claim 50, wherein said cover is threaded.

52. The implant of claim 50, wherein said cover includes at least one opening therethrough.

53. The implant of claim 50, wherein said cover is configured to cooperatively engage a tool for engaging said cover to said implant.

54. The implant of claim 45, wherein said top and said bottom further comprise at least a second opening.

55. The implant of claim 45, wherein at least one of said openings are approximately 1 mm to 3 mm in diameter.

56. The implant of claim 45, wherein at least one of said openings is macroscopic in size.

57. The implant of claim 45, wherein at least one of said openings is micro-sized.

58. The implant of claim 45, wherein at least some of said openings in said top and said bottom form a channel through said implant.

59. The implant of claim 45, wherein said trailing end includes at least one perforation.

60. The implant of claim 45, wherein the junctions of said sides and at least one of said trailing end and said leading end are rounded.

61. The implant of claim 45, wherein said sides are generally parallel to one another.

62. The implant of claim 45, wherein said sides are generally flat.

63. The implant of claim 45, wherein said implant has a width that is approximately 32 mm for use in the lumbar spine.

64. The implant of claim 45, wherein said implant has a generally rectangular cross section along at least a portion of its length.

65. The implant of claim 45, wherein said leading end is at least in part non-linear.

66. The implant of claim 45, wherein at least a portion of said leading end is tapered for facilitating insertion of said implant between the two adjacent vertebral bodies.

67. The implant of claim 45, wherein said leading end is curved.

68. The implant of claim 67, wherein said leading end is convex.

69. The implant of claim 67, wherein said leading end generally conforms to the disc space proximate the posterior aspect of the vertebral bodies.

70. The implant of claim 45, wherein said trailing end is curved.

71. The implant of claim 70, wherein said trailing end is convex.

72. The implant of claim 45, wherein said implant has a length along a mid-longitudinal axis of said implant, said length having a maximum that is less than the posterior to anterior depth of the vertebral body.

73. The implant of claim 45, wherein said implant is adapted for insertion from the anterior aspect of the vertebral bodies.

74. The implant of claim 45, wherein said implant is sized to replace a substantial portion of the disc with a single implant.

75. The implant of claim 45, wherein said implant has a height at least as great as the stored height of the disc space.

76. The implant of claim 45, wherein said top and said bottom are generally parallel.

77. The implant of claim 45, wherein said top and said bottom have a porous surface.

78. The implant of claim 45, wherein said top and said bottom have a bone ingrowth surface.

79. The implant of claim 45, wherein said implant has an exterior surface that is at least in part porous.

80. The implant of claim 45, wherein said implant material is porous.

81. The implant of claim 45, in combination with a fusion promoting material other than bone.

82. The implant of claim 45, wherein said implant comprises a bone ingrowth material other than bone.

83. The implant of claim 45, further comprising a material that intrinsically participates in the growth of bone from one of the adjacent vertebral bodies to the other of the adjacent vertebral bodies.

84. The implant of claim 45, wherein said implant is treated with a fusion promoting substance.

85. The implant of claim 84, wherein said fusion promoting substance is autogenous bone.

86. The implant of claim 45, wherein said implant material is stronger than bone.

87. The implant of claim 45, further in combination with an osteogenic material.

88. The implant of claim 87, wherein said osteogenic material is a material other than bone.

89. The implant of claim 45, wherein said implant is adapted to be centrally placed within the disc space.

90. The implant of claim 45, wherein said implant is adapted for insertion from the posterior aspect of the vertebral bodies.

91. An artificial interbody spinal fusion implant for insertion within an implantation space formed across the height of a disc space between vertebral bodies of a human spine, the vertebral bodies having an anterior aspect and a posterior aspect and a depth therebetween, said implant comprising:

a leading end for insertion first into the disc space and a trailing end opposite said leading end, said implant having a length from said leading end to said trailing end;

a top and a bottom between said leading and trailing ends adapted to space apart the adjacent vertebral bodies, said top and said bottom having at least one opening therethrough, said openings being in communication with one another to permit for the growth of bone from adjacent vertebral body to adjacent vertebral body through said implant, said implant having a height from said top to said bottom;

opposite sides between said top and said bottom, and between said leading and trailing ends, said implant having a width from one of said sides to the other of said sides, said sides having at least one aperture therethrough in communication with said openings in said top and said bottom;

the width of said implant being greater than one-half the width of those vertebral bodies that are adjacent the implantation space into which said implant is adapted to be inserted, the height of said implant being less than the width of said implant;

said implant being formed at least in part of a material other than bone; and

said implant being configured to be wholly contained within the perimeter of the adjacent vertebral bodies.

92. The implant of claim 91, wherein each of said top and said bottom comprises an interior surface, said interior surfaces being spaced apart to define a hollow interior in communication with said openings.

93. The implant of claim 92, wherein said implant includes an access opening for accessing said hollow interior.

94. The implant of claim 93, wherein said access opening is configured to permit insertion of osteogenic material into said hollow interior.

95. The implant of claim 94, wherein said osteogenic material includes a fusion promoting material.

96. The implant of claim 94, wherein said osteogenic material is bone.

97. The implant of claim 94, wherein said osteogenic material is a material other than bone.

98. The implant of claim 93 further comprising a cover for closing said access opening.

99. The implant of claim 98, wherein said cover cooperatively engages said access opening.

100. The implant of claim 98, wherein said cover is threaded.

101. The implant of claim 98, wherein said cover includes at least one opening therethrough.

102. The implant of claim 98, wherein said cover is configured to cooperatively engage a tool for engaging said cover to said implant.

103. The implant of claim 91, wherein said top and said bottom further comprise at least a second opening.

104. The implant of claim 91, wherein at least one of said openings are approximately 1 mm to 3 mm in diameter.

105. The implant of claim 91, wherein at least one of said openings is macroscopic in size.

106. The implant of claim 91, wherein at least one of said openings is micro-sized.

107. The implant of claim 91, wherein at least some of said openings in said top and said bottom form a channel through said implant.

108. The implant of claim 91, wherein said trailing end includes at least one perforation.

109. The implant of claim 91, wherein said at least one aperture is sized in the range of approximately 1 mm to 3 mm.

110. The implant of claim 91, wherein the junctions of said sides and at least one of said trailing end and said leading end are rounded.

111. The implant of claim 91, wherein said sides are generally parallel to one another.

112. The implant of claim 91, wherein said sides are generally flat.

113. The implant of claim 91, wherein said implant has a width that is approximately 32 mm for use in the lumbar spine.

114. The implant of claim 91, wherein said implant has a generally rectangular cross section along at least a portion of its length.

115. The implant of claim 91, wherein said leading end is at least in part non-linear.

116. The implant of claim 91, wherein at least a portion of said leading end is tapered for facilitating insertion of said implant between the two adjacent vertebral bodies.

117. The implant of claim 91, wherein said leading end is curved.

118. The implant of claim 117, wherein said leading end is convex.

119. The implant of claim 117, wherein said leading generally conforms to the disc space proximate the posterior aspect of the vertebral bodies.

120. The implant of claim 91, wherein said trailing end is curved.

121. The implant of claim 120, wherein said trailing end is convex.

122. The implant of claim 91, wherein said implant has a length along a mid-longitudinal axis of said implant, said length having a maximum that is less than the posterior to anterior depth of the vertebral body.

123. The implant of claim 91, wherein said implant is adapted for insertion from the anterior aspect of the vertebral bodies.

124. The implant of claim 91, wherein said implant is sized to replace a substantial portion of the disc with a single implant.

125. The implant of claim 91, wherein said implant has a height at least as great as the restored height of the disc space.

126. The implant of claim 91, wherein said top and said bottom are generally parallel.

127. The implant of claim 91, wherein said top and said bottom have a porous surface.

128. The implant of claim 91, wherein said top and said bottom have a bone ingrowth surface.

129. The implant of claim 91, wherein said implant has an exterior surface that is at least in part porous.

130. The implant of claim 91, wherein said implant material is porous.

131. The implant of claim 91, in combination with a fusion promoting material other than bone.

132. The implant of claim 91, wherein said implant comprises a bone ingrowth material other than bone.

133. The implant of claim 91, further comprising a material that intrinsically participates in the growth of bone from one of the adjacent vertebral bodies to the other of the adjacent vertebral bodies.

134. The implant of claim 91, wherein said implant is treated with a fusion promoting substance.

135. The implant of claim 134, wherein said fusion promoting substance is autogenous bone.

136. The implant of claim 91, wherein said implant material is stronger than bone.

137. The implant of claim 91, further in combination with an osteogenic material.

138. The implant of claim 137, wherein said osteogenic material is a material other than bone.

139. The implant of claim 91, wherein said implant is adapted to be centrally placed within the disc space.

140. The implant of claim 91, wherein said implant is adapted for insertion from the posterior aspect of the vertebral bodies.

141. An artificial interbody spinal fusion implant for insertion within an implantation space formed across the height of a disc space between vertebral bodies of a human spine, the vertebral bodies having an anterior aspect and a posterior aspect and a depth therebetween, said implant comprising:

a leading end for insertion first into the disc space and a trailing end opposite said leading end, said implant having a length from said leading end to said trailing end;

a top and a bottom between said leading and trailing ends adapted to space apart the adjacent vertebral bodies, said top and said bottom having at least one opening therethrough, said openings being in communication with one another to permit for the growth of bone from adjacent vertebral body to adjacent vertebral body through said implant, said implant having a height from said top to said bottom;

opposite sides between said top and said bottom, and between said leading and trailing ends, said implant having a width from one of said sides to the other of said sides;

the width of said implant being greater than one-half the width of those vertebral bodies that are adjacent the implantation space into which said implant is adapted to be inserted, the height of said implant being less than the width of said implant;

said implant being formed at least in part of a material other than bone; and

said implant being configured to be wholly contained within the perimeter of the adjacent vertebral bodies and to engage a driving instrument for implanting said implant within the disc space between the two adjacent vertebrae.

142. The implant of claim 141, wherein each of said top and said bottom comprises an interior surface, said interior surfaces being spaced apart to define a hollow interior in communication with said openings.

143. The implant of claim 142, wherein said implant includes an access opening for accessing said hollow interior.

144. The implant of claim 143, wherein said access opening is configured to permit insertion of osteogenic material into said hollow interior.

145. The implant of claim 144, wherein said osteogenic material includes a fusion promoting material.

146. The implant of claim 144, wherein said osteogenic material is bone.

147. The implant of claim 144, wherein said osteogenic material is a material other than bone.

148. The implant of claim 143 further comprising a cover for closing said access opening.

149. The implant of claim 148, wherein said cover cooperatively engages said access opening.

150. The implant of claim 148, wherein said cover is threaded.

151. The implant of claim 148, wherein said cover includes at least one opening therethrough.

152. The implant of claim 148, wherein said cover is configured to cooperatively engage a tool for engaging said cover to said implant.

153. The implant of claim 141, wherein said top and said bottom further comprise at least a second opening.

154. The implant of claim 141, wherein at least one of said openings are approximately 1 mm to 3 mm in diameter.

155. The implant of claim 141, wherein at least one of said openings is macroscopic in size.

156. The implant of claim 141, wherein at least one of said openings is micro-sized.

157. The implant of claim 141, wherein at least some of said openings in said top and said bottom form a channel through said implant.

158. The implant of claim 141, wherein said trailing end includes at least one perforation.

159. The implant of claim 141, wherein said sides have at least one aperture.

160. The implant of claim 159, wherein said at least one aperture is sized in the range of approximately 1 mm to 3 mm.

161. The implant of claim 159, wherein said at least one aperture is in communication with said openings in said top and said bottom.

162. The implant of claim 141, wherein the junctions of said sides and at least one of said trailing end and said leading end are rounded.

163. The implant of claim 141, wherein said sides are generally parallel to one another.

164. The implant of claim 141, wherein said sides are generally flat.

165. The implant of claim 141, wherein said implant has a width that is approximately 32 mm for use in the lumbar spine.

166. The implant of claim 141, wherein said implant has a generally rectangular cross section along at least a portion of its length.

167. The implant of claim 141, wherein said leading end is at least in part non-linear.

168. The implant of claim 141, wherein at least a portion of said leading end is tapered for facilitating insertion of said implant between the two adjacent vertebral bodies.

169. The implant of claim 141, wherein said leading end is curved.

170. The implant of claim 169, wherein said leading end is convex.

171. The implant of claim 169, wherein said leading end generally conforms to the disc space proximate the posterior aspect of the vertebral bodies.

172. The implant of claim 141, wherein said trailing end is curved.

173. The implant of claim 172, wherein said trailing end is convex.

174. The implant of claim 141, wherein said implant has a length along a mid-longitudinal axis of said implant, said length having a maximum that is less than the posterior to anterior depth of the vertebral body.

175. The implant of claim 141, wherein said implant is adapted for insertion from the anterior aspect of the vertebral bodies.

176. The implant of claim 141, wherein said implant is sized to replace a substantial portion of the disc with a single implant.

177. The implant of claim 141, wherein said implant has a height at least as great as the restored height of the disc space.

178. The implant of claim 141, wherein said top and said bottom are generally parallel.

179. The implant of claim 141, wherein said top and said bottom have a porous surface.

180. The implant of claim 141, wherein said top and said bottom have a bone ingrowth surface.

181. The implant of claim 141, wherein said implant has an exterior surface that is at least in part porous.

182. The implant of claim 141, wherein said implant material is porous.

183. The implant of claim 141, in combination with a fusion promoting material other than bone.

184. The implant of claim 141, wherein said implant comprises a bone ingrowth material other than bone.

185. The implant of claim 141, further comprising a material that intrinsically participates in the growth of bone from one of the adjacent vertebral bodies to the other of the adjacent vertebral bodies.

186. The implant of claim 141, wherein said implant is treated with a fusion promoting substance.

187. The implant of claim 186, wherein said fusion promoting substance is autogenous bone.

188. The implant of claim 141, wherein said implant material is stronger than bone.

189. The implant of claim 141, further in combination with an osteogenic material.

190. The implant of claim 189, wherein said osteogenic material is a material other than bone.

191. The implant of claim 141, wherein said implant is adapted to be centrally placed within the disc space.

192. The implant of claim 141, wherein said implant is adapted for insertion from the posterior aspect of the vertebral bodies.