CA2495373A1

CA2495373A1 - Controlled artificial intervertebral disc implant

Info

Publication number: CA2495373A1
Application number: CA002495373A
Authority: CA
Inventors: David Gerber; Justin K. Coppes; Christopher M. Angelucci; Pascal Stihl; Michael L. Ii Boyer; David Paul
Original assignee: Individual
Current assignee: Synthes USA LLC
Priority date: 2002-08-15
Filing date: 2003-08-15
Publication date: 2004-02-26
Anticipated expiration: 2023-08-15
Also published as: BR0313499A; WO2004016217A3; EP1542626A2; EP1542626B1; JP4456481B2; JP2006514559A; US7563286B2; US20120016480A1; US20090270992A1; CA2495373C; US20050251260A1; US8435301B2; WO2004016217A2

Abstract

The invention relates to an artificial intervertebral disc for placement between adjacent vertebrae. The artificial intervertebral disc is preferably designed to restore disc height and natural disc curvature, allow for a natural range of motion, absorb shock and provide resistance to motion and axial compression. Furthermore, the intervertebral disc may be used in the cervical, the thoracic, or the lumbar regions of the spine. The artificial intervertebral disc may include either singularly or in combination: an interior including at least one spring member preferably incorporating a arcuate surface member, a flexible core, the flexible core preferably being a slotted core, a ring spring, a winged leaf spring, or a leaf spring, or. The articulating member preferably being attached to one of the endplate by an intermediate shock absorbing element.

Claims

1. An intervertebral disc for placement between first and second vertebrae comprising:
an upper endplate having a first inner surface and a first outer surface, the first outer surface configured to contact the first vertebra;
a lower endplate having a second inner surface and a second outer surface, the second outer surface configured to contact the second vertebra;
a membrane extending between the upper endplate and the lower endplate; and at least one resilient member disposed between the upper and lower endplates;
the resilient member associated with at least one arcuate surface member configured to articulate within at least one socket associated with at least one of the endplates.

2. The intervertebral disc according to claim 1, wherein the at least one resilient member further comprises a first end and a second end, the first end associated with the arcuate surface member, the second end disposed within a recess formed in the inner surface of one of the endplates.

3. The intervertebral disc according to claim 1 or 2, wherein the at least one arcuate surface member is fixed within the recess formed on the inner surface of one of the endplates.

4. The intervertebral disc according to any one of the preceding claims 1 - 3, wherein the at least one resilient member further comprises first and second ends, each end further being connected to a separate arcuate surface member.

5. The intervertebral disc according to any one of the preceding claims 1 - 4, wherein the at least one arcuate member and the resilient member are configured to allow translational movement between the upper and lower endplates.

6. The intervertebral disc according to any one of the preceding claims, 1 -5, wherein the at least one resilient member comprises at least one first resilient member and a plurality of second resilient members.

7. The intervertebral disc according to claim 6, wherein the at least one first resilient member has a first spring constant, the at least one second resilient member has a second spring constant, the first and second spring constants being substantially unequal.

8. The intervertebral disc according to claim 7, wherein the first spring constant is substantially greater than the second spring constant.

9. The intervertebral disc according to claim 8, further comprising a third resilient member, the second and third resilient members disposed nearer to a peripheral edge of the disc than the first resilient member.

10. The intervertebral disc according to claim 6, wherein the first resilient member and the plurality of second resilient members are each attached to at least one respective arcuate surface member configured to articulate within a corresponding respective socket formed on the inner surface of one of the endplates.

11. The intervertebral disc according to any one of the preceding claims 1 -10, further comprising at least one elastomeric strut disposed between the upper and lower endplates.

12. The intervertebral disc according to any one of the preceding claims 1 -11, further comprising a casing member disposed adjacent the at least one resilient member, the casing member having an articulating surface configured to engage the arcuate surface member associated with the resilient member.

13. The intervertebral disc according to any one of the preceding claims 1 -12, wherein the resilient member and arcuate surface member are integrally formed.

14. The intervertebral disc according to any one of the preceding claims 1 -13, further comprising a membrane disposed between the upper and lower endplates, the membrane encapsulates at least a portion of the at least one resilient member.

15. The intervertebral disc according to any one of the preceding claims 1 -14, wherein the membrane encapsulates the upper and lower endplates.

16. The intervertebral disc according to any one of the preceding claims 1 -15, wherein the membrane is formed of an elastomeric material.

17. The intervertebral disc according to any one of the preceding claims 1 -16, wherein the membrane comprises a bellow.

18. The intervertebral disc according to any one of the preceding claims 1 -17, wherein the endplates and membrane define an interior volume, the volume being at least partially filled with a fluid.

19. The intervertebral disc according to claim 18, further comprising a valve in communication with the volume for at least partially filing the volume with the fluid.

20. The intervertebral disc according to claim 18 or 19, wherein the fluid is compressible.

21. The intervertebral disc according to claim 18 or 19, wherein the fluid is incompressible.

22. The intervertebral disc according to any one of the preceding claims 18 -21, wherein the membrane is at least semi-permeable.

23. The intervertebral disc according to any one of the preceding claims 18 -22, wherein the membrane is non-permeable.

24. The intervertebral disc according to any one of the preceding claims 1 -23, wherein at least one of the endplates is formed from a material selected from the group consisting of metal, polymer, ceramic aid composite.

25. The intervertebral disc according to any one of the preceding claims 1 -24, wherein at least one of the endplates is formed of bone material selected from the group consisting of cortical, cancellous, allograft, autograft, xenograft, demineralized or partially demineralized bone.

26. The intervertebral disc according to any one of the preceding claims 1 -25, further comprising migration-resistant structures diseased on at least one of the first and second outer surfaces.

27. The intervertebral disc according to any one of the preceding claims 1 -26, further comprising permanent fixation means disposed on at least one of the first and second outer surfaces.

28. The intervertebral disc according to any one of the preceding claims 1 -27, further comprising implant instrumentation attachment, guiding, or retaining structures disposed on at least one of the first or second end plates.

29. The intervertebral disc for placement between first and second vertebrae comprising:
a first endplate having a first inner surface and a first outer surface, the first outer surface contacting the first vertebra;
a second endplate having a second inner surface and a second outer surface, the second outer surface contacting the second vertebra;
a membrane extending between the first and second endplates; and at least one leaf spring disposed between the endplates, the leaf spring having first and second ends, the first end attached to the first endplate and the second end configured to be movable laterally along the inner surface of the first endplate in response to a force on the leaf spring.

30. The intervertebral disc according to claim 29, wherein the leaf spring second end further comprises a roller configured to allow the second end to roll along the inner surface of the first end plate in response to a force on the leaf spring.

31. The intervertebral disc according to claim 29 or 30, wherein the second end further comprises an axle for pivotably mounting the roller.

32. The intervertebral disc according to any claim 31, wherein the roller comprises a rounded end.

33. The intervertebral disc according to any one of the preceding claims 29 -32, wherein the leaf spring further comprises an intermediate portion disposed between the first and second ends, the intermediate portion having an articulating surface configured to mate with the inner surface of the second endplate.

34. The intervertebral disc according to claim 33, wherein the inner surface of the second endplate further comprises an articulating surface configured to mate with the articulating surface of the leaf spring intermediate portion.

35. The intervertebral disc according to claim 33, wherein the inner surface of the second endplate further comprises a pad configured to mate with the articulating surface of the leaf spring intermediate portion.

36. The intervertebral disc according to any one of the preceding claims 29 -35, further comprising a membrane disposed between the upper and lower endplates, the membrane encapsulates the leaf spring.

37. The intervertebral disc according to any one of the preceding claims 29 -36, wherein the membrane encapsulates the upper and lower endplates.

38. The intervertebral disc according to any one of the preceding clams 29 -37, wherein the membrane is formed of an elastomeric material.

39. The intervertebral disc according to away one of the preceding claims 29 -38, wherein the membrane comprises a bellow.

40. The intervertebral disc according to any one of the preceding claims 29 -39, wherein the endplates and membrane define an interior volume, the volume being at least partially filled with a fluid.

41. The intervertebral disc according to claim 40, further comprising a valve in communication with the volume for at least partially filling the volume with the fluid.

42. The intervertebral disc according to claim 40 or 41, wherein the fluid is compressible.

43. The intervertebral disc according to claim 40 or 41, wherein the fluid is incompressible.

44. The intervertebral disc according to any one of the preceding claims 40 -43, wherein the membrane is at least semi-permeable.

45. The intervertebral disc according to any one of the preceding claims 40 -43, wherein the membrane is non permeable.

46. The intervertebral disc according to any one of the preceding claims 29 -45, wherein at least one of the endplates is formed from a material selected from the group consisting of metal, polymer, ceramic and composite.

47. The intervertebral disc according to any one of the preceding claims 29 -46, wherein at least one of the endplates is formed of bone material selected from the group consisting of cortical, cancellous, allograft, autograft, xenograft, demineralized or partially demineralized bone.

48. The intervertebral disc according to any one of the preceding claims claim 29 - 47, further comprising migration-resistant structures disposed on at least one of the first and second outer surfaces.

49. The intervertebral disc according to any one of the preceding claims 29 -48, further comprising permanent fixation means disposed on at least one of the first and second outer surfaces.

50. The intervertebral disc according to any one of the preceding claims 29 -49, wherein at least one of the endplates is formed of bone material selected from the group consisting of cortical, cancellous, allograft, autograft, xenograft, demineralized or partially demineralized bone.

51. An intervertebral disc for placement between first and second vertebrae comprising:
a first endplate having a first inner surface and a first outer surface, the first outer surface contacting the first vertebra;
a second endplate having a second inner surface and a second outer surface, the second outer surface contacting the second vertebra;
a membrane extending between the first and second endplates;
an articulating member disposed between the first and second endplates, the articulating member having a first and second surface, the first surface being configured to mate with the inner surface of at least the endplate; and a shock absorbing element disposed between the second surface and one of the endplates.

52. The intervertebral disc according to claim 51, wherein the inner surface of one of the endplates further comprises an articulating surface configured to mate with the articulating member.

53. The intervertebral disc according in claim 51 or 52, wherein the articulating surface further comprises an articulating pad.

54. The intervertebral disc according to any one of the preceding claims 51 -53, wherein the articulating surface further comprises a recess sized and configured receive at least a portion of the articulating pad, the recess further configured to allow the articulating pad to translate in at least one direction with respect to the articulating surface.

55. The intervertebral disc according to any one of the preceding claims 51 -54, further comprising a membrane disposed between the upper and lower endplates, the membrane encapsulates the articulating member.

56.~The intervertebral disc according to any one of the preceding claims 51 -55, wherein the membrane encapsulates the first and second endplates.

57.~The intervertebral disc according to any one of the preceding claims 51 -56, wherein the membrane is formed of an elastomeric material.

58.~The intervertebral disc according to any one of the preceding claims 51 -57, wherein the membrane comprises a bellow, and wherein the bellow encapsulates at least the shock absorbing element.

59.~The intervertebral disc according to any one of the preceding claims 51 -58, wherein the endplates and membrane define an interior volume, the volume being at least partially filled with a fluid.

60.~The intervertebral disc according to claims 59, further comprising a valve in communication with the volume for at least partially filling the volume with the fluid.

61.~The intervertebral disc according to claims 59, wherein the fluid is compressible.

62.~The intervertebral disc according to claims 59 or 60, wherein the fluid is incompressible.

63.~The intervertebral disc according to claims 59 or 60, wherein the membrane is at least semi-permeable.

64.~The intervertebral disc according to claims 59 or 60, wherein the membrane is non-permeable.

65.~The intervertebral disc according to claims 51, wherein at least one of the endplates is formed from a material selected from the group consisting of metal, polymer, ceramic and composite.

66.~The intervertebral disc according to any one of the preceding claims 51 -65, wherein at least one of the endplates is formed of bone material selected from the group consisting of cortical, cancellous, allograft, autograft, xenograft, demineralized or partially demineralized bone.

67. The intervertebral disc according to any one of the preceding claims 51 -66, further comprising migration-resistant structures disposed on at least one of the first and second outer surfaces.

68. The intervertebral disc according to any one of the preceding claims 51 -67, further comprising permanent fixation means disposed on at least one of the first and second outer surfaces.

69. The intervertebral disc according to any one of the preceding claims 51 -68, further comprising implant instrumentation attachment, guiding, or retaining structures disposed an at least one of the first and second inner and/or outer surfaces.

70. The intervertebral disc for placement between first and second vertebrae comprising:
a first endplate having a first inner surface and a first outer surface, the first outer surface contacting the first vertebra;
a second endplate having a second inner surface and a second outer surface, the second outer surface contacting the second vertebra; and a slatted core disposed between the first and second endplates, the slotted core having a first and second surface, the first surface configured to mate with a pocket formed on the inner surface of first endplate, and the second surface comprising as articulating surface configured to mate with a corresponding surface associated with the second endplate.

71. The intervertebral disc according to claim 70, the slotted core first surface having a first diameter and the pocket having a second diameter larger than the first diameter so that the slotted core may translate within the pocket.

72. The intervertebral disc according to claim 70 or 71, further comprising a lid disposed between the first and second endplates, the lid configured to engage at least a portion of the pocket and the slotted core to axially retain the core within the pocket.

73. The intervertebral disc according to any one of the preceding claims 70 -72, wherein the second surface of the slotted core is configured to articulate within the second endplate corresponding surface.

74. The intervertebral disc according to any one of the preceding claims 70 -73, further comprising a membrane disposed between the upper and lower endplates, the membrane encapsulating at least the slotted core and pocket.

75. The intervertebral disc according to claim 74, wherein the membrane further encapsulates the upper and lower endplates.

76. The intervertebral disc according to claim 74, wherein the membrane is formed of an elastomeric material.

77. The intervertebral disc according to any one of the preceding claims 74 -76, wherein the membrane comprises a bellow.

78. The intervertebral disc according to any one of the preceding claims 74 -77, wherein the endplates and membrane define an interior volume, the volume being at least partially filled a fluid.

79. The intervertebral disc according to claim 78, further comprising a valve in communication with the volume for at least partially filling the volume with the fluid.

80. The intervertebral disc according to claim 78 or 79, wherein the fluid is compressible.

81. The intervertebral disc according to claim 78 or 79, wherein the fluid is incompressible.

82. The intervertebral disc according to any one of the preceding claims 70 -81, wherein at least one of the endplates is formed from a material selected from the group consisting of metal, polymer, ceramic and composite.

83. The intervertebral disc according to any one of the preceding claims 70 -82, wherein at least one of the endplates is formed of bone material selected from the group consisting of cortical, cancellous, allograft, autograft, xenograft, demineralized or partially demineralized bone.

84. The intervertebral disc according to any one of the preceding claims 70 -83, further comprising migration-resistant structures disposed on at least one of the first and second outer surfaces.

85. The intervertebral disc according to any one of the preceding claims 70 -84, further comprising permanent fixation means disposed on at least one of the first and second outer surfaces.

86. The intervertebral disc according to any one of the preceding claims 70 -85, further comprising implant instrumentation attachment, guiding, or retaining structures disposed on at least one of the first and second inner or outer surfaces.

87. An intervertebral disc for placement between first and second vertebrae comprising:
a first endplate having a first inner surface and a first outer surface, the first outer surface contacting the first vertebra;
a second end plate having a second inner surface and a second outer surface, the second outer surface contacting the second vertebra;
a cap having a top surface and bottom surface; the top surface being configured to mate with the inner surface of the first endplate; and a ring spring disposed between the bottom surface of the cap and the inner surface of the second endplate.

88. The intervertebral disc according to claim 87, wherein the ring spring has first and second surfaces, the first surface configured to mate with the bottom surface of the cap, and the second surface configured to mate with the pocket formed on the inner surface of the second endplate.

89. The intervertebral disc according to claim 87 or 88, further comprising a slot defining a gap between first and second end faces of the ring spring, wherein the gap is sized to allow the ring spring to resiliently compress so that the end faces approach each other when a compressive force is placed on the ring spring by the cap.

90. The intervertebral disc according to any one of the preceding claims 87 -89, the ring spring further comprising a first diameter, and the bottom surface of the cap having an axial protrusion comprising a second diameter, the first diameter being substantially larger than the second diameter, wherein when the bottom surface of the cap engages the top first surface of the ring spring, the cap may translate with respect to the ring spring.

91. The intervertebral disc according to any one of the preceding claims 87 -90, further comprising a plurality of slots located between the first and second surfaces, the slots operative to render at least a portion of the ring spring resiliently compressible when a compressive force is placed on the ring spring by the cap.

92. The intervertebral disc according to claim 91, the protrusion comprising a radial lip having an outer diameter larger than the first diameter of the ring spring, the lip allowing the cap protrusion to be press-fit into the ring spring first diameter.

93. The intervertebral disc according to any one of the preceding claims 87 -92, further comprising a lid disposed between the first and second end plates, the lid configured to engage at least a portion of the pocket and either the ring spring or the cap to axially retain the ring spring and the cap within the pocket.

94. The intervertebral disc according to any one of the preceding claims 87 -93, further comprising a membrane disposed between the upper and lower endplates.

95. The intervertebral disc according to any one of the preceding claims 87 -94, further comprising a membrane disposed between the upper and lower endplates, the membrane encapsulating at least the cap, ring spring and pocket.

96. The intervertebral disc according to claim 95, wherein the membrane encapsulates the upper and lower endplates.

97. The intervertebral disc according to claim 95 or 96, wherein the membrane is formed of an elastomeric material.

98. The intervertebral disc according to any one of the preceding claims 95 -97, wherein the membrane comprises a bellow.

99. The intervertebral disc according to any one of the preceding claims 95 -98, wherein the endplates and membrane define an interior volume, the volume being at least partially filled a fluid.

100. The intervertebral disc according to claim 99, further comprising a valve in communication with the volume for at least partially filling the volume with the fluid.

101. The intervertebral disc according to claim 99 or 100, wherein the fluid is incompressible.

102. The intervertebral disc according to claim 99 or 100, wherein the fluid is compressible.

103. The intervertebral disc according to any one of the preceding claims 87 -102, wherein at least one of the endplates is formed from a material selected from the group consisting of metal, polymer, ceramic and composite.

104. The intervertebral disc according to any one of the preceding claims 87 -103, wherein at least one of the endplates is formed of bone material selected from the group consisting of cortical, cancellous, allograft, autograft, xenograft, demineralized or partially demineralized bone.

105. The intervertebral disc recording to any one of the preceding claims 87 -104, further comprising migration-resistant structures disposed on at least one of the first and second outer surfaces.

106. The intervertebral disc according to any one of the preceding claims 87 -105, further comprising permanent fixation means disposed on at least one of the first and second outer surfaces.

107. The intervertebral disc according to any one of the preceding claims 87 -106, further comprising implant instrumentation attachment, guiding, or retaining structures disposed on at least one of the first and second inner or outer surfaces.

108. An intervertebral disc for placement between first and second vertebrae comprising:
a first endplate having a first inner surface and a first outer surface, the first outer surface contacting the first vertebra;
a second endplate having a second inner surface and a second outer surface, the second outer surface contacting the second vertebra;
a leaf spring having first and second resilient ends, configured to engage the second endplate, and a length, the leaf spring further comprising a central body having first and second surfaces, the first surface comprising an articulating surface.

109. The intervertebral disc according to claim 108, wherein the second endplate further comprises a recess having a length smaller than the leaf spring length, wherein when the leaf spring engages the second endplate so that the first and second resilient ends are supported on the inner surface of the endplate and the central body is positioned over the endplate recess, at least a portion of the central body may nave into the recess when a compressive force is applied to the leaf spring first surface allowing the second surface to contact the recess surface.

110. The intervertebral disc according to claim 108 or 109, the recess further comprising a recess surface, the leaf spring second surface stud the recess surface configured to define a gap therebetween so that when a predetermined compressive force is applied to the leaf spring first surface the leaf spring second surface contacts at least a portion of the recess surface.

111. The intervertebral disc recording to any one of the preceding claims 109 -110, wherein the central body and the recess are configured so that the leaf spring may translate in at least one direction with respect to the second end plate.

112. The intervertebral disc according to any one of the preceding claims 108 -111, wherein the first endplate further comprises an inner surface having an articulating surface configured to correspond with the leaf spring articulating surface.

113. The intervertebral disc according to claim 112, wherein the articulating surfaces are configured to allow the leaf spring to articulate, and to translate, relative to the first endplate.

114. The intervertebral disc according to any one of the preceding claims 108 -113, further comprising a membrane disposed between the first and second endplates.

115. The intervertebral disc according to claim 114, further comprising a membrane disposed between the upper and lower endplates, the membrane encapsulating at least the leaf spring.

116. The intervertebral disc according to claim 114 or 115, wherein the membrane encapsulates the first and second endplates.

117. The intervertebral disc according to any one of the preceding claims 114 -116, wherein the membrane is formed of an elastomeric material.

118. The intervertebral disc according to any one of the preceding claims 114 -117, wherein the membrane comprises a bellow.

119. The intervertebral disc according to any one of the preceding claims 114 -118, wherein the endplates and membrane define an interior volume, the volume being at least partially filled a fluid.

120. The intervertebral disc according to claim 119, further comprising a valve in communication with the volume for at least partially filling the volume with the fluid.

121. The intervertebral disc according to claim 119 or 120, wherein the fluid is incompressible.

122. The intervertebral disc cording to any one of the preceding claims 108 -121, wherein at least one of the endplates is formed from a material selected from the group consisting of metal, polymer, ceramic and composite.

123. The intervertebral disc according to any one of the preceding claims 108 -122, wherein at least one of the endplates is formed of bone material selected from the group consisting of cortical, cancellous, allograft, autograft, xenograft, demineralized or partially demineralized bone.

124. The intervertebral disc according co any one of the preceding claims 108 -123, further comprising migration-resistant structures disposed on at least one of the first and second outer surfaces.

125. The intervertebral disc according to any one of the preceding claims 108 -124, further comprising permanent fixation means disposed on at least one of the first and second outer surfaces.

126. The intervertebral disc according to any one of the preceding claims 108 -125, further comprising implant instrumentation attachment, guiding, or retaining structures disposed an at least one of the first and second inner or outer surfaces.

127. An intervertebral disc for placement between first and second vertebrae comprising:
a first endplate having a first inner surface and a first outer surface, the first outer surface configured for contacting the first vertebra;
a second endplate having a second inner surface and a second outer surface, the second outer surface configured for contacting the second vertebra;
a first articulation member having a first surface associated with the first endplate, a leaf spring having at least a first surface associated with the second endplate and a second surface associated pith a second surface of the first articulation member;

wherein the first articulation member is configured to allow the first and second endplates to articulate with respect to each other and the leaf spring is configured to allow the end plates to approach one another in response to a compressive force applied to at least one of the end plates.

128. The intervertebral disc according to claim 127, wherein at least one of the first endplate inner surface and the first articulation member first surface comprises a concave surface, the other surface being convex, the surfaces configured to allow the articulation member to articulate with respect the first endplate.

129. The intervertebral disc according to claim 127 or 128, wherein the first endplate inner surface comprises a concave shape, and the first articulation member comprises a corresponding convex shape.

130. The intervertebral disc according to any one of the preceding claims 127 -129, further comprising a second articulation member having a first surface associated with the first endplate inner surface and a second surface associated with the first articulation member first surface.

131. The intervertebral disc according to claim 130, wherein the second articulation member second surface is concave and configured to correspond to a convex first surfaces of the first articulation member.

132. The intervertebral disc according to claim 131, wherein the concave and convex surfaces are configured to allow both articulation and translation between the articulation members.

133. The intervertebral disc according to any one of the preceding claims 130 -132, wherein at least one of the articulation members comprises a material that is different from the material of one of the first or second endplates.

134. The intervertebral disc according to any one of the preceding claims 127 -133, wherein the first endplate inner surface and the articulation member first surface are further configured to allow the articulation member to translate relative to the first endplate.

135. The intervertebral disc according to any one of the preceding claims 127 -134, the second endplate further comprising a recess in the second inner surface, the leaf spring having a length sufficient to span the recess so that at least opposite ends of the leaf spring are supported by the inner surface and a central portion of the leaf spring is positioned over the recess, wherein when the central portion may move into the recess when a compressive force is applied to a second surface of the leaf spring.

136. The intervertebral disc according to claim 135, the second endplate further comprising a perimeter edge sized and configured to allow the leaf spring to translate with respect to the second endplate in at least one direction.

137. The intervertebral disc according to claim 135 or 136, the second endplate further comprising a perimeter edge sized and configured to prevent the leaf spring from translating in at least one other direction.

138. The intervertebral disc according to any one of the preceding claims 134 -137, the leaf spring second surface further comprising a recess configured to accept a projection formed on a second surface of the articulation member.

139. The intervertebral disc according to claim 138, wherein the recess and projection are sized and configured to allow the articulation member to translate in at least one direction relative to the leaf spring.

140. The intervertebral disc according to any one of the preceding claims 136 -139, further comprising a cap member configured to engage at least a portion of the second endplate, and to cover at least a portion of the leaf spring to prevent the leaf spring from axially disengaging from the second endplate.

141. The intervertebral disc according to any one of the preceding claims 135 -140, the cap member further comprising at least one raised ridge configured to contact at least one raised ridge associated with the first endplate to limit articulation between the endplates in at least one direction.

142. The intervertebral disc according to claim 141, wherein the raised ridges have corresponding flat surface profiles.

143. The intervertebral disc according to claim 141 or 142, wherein the raised ridges have correspondingly angled surfaces.

144. The intervertebral disc according to any one of the preceding claims 127 -143, wherein at least one of the endplates is formed from a material selected from the group consisting of metal, polymer, ceramic and composite.

145. The intervertebral disc according to any one of the preceding claims 127 -144, wherein at least one of the endplates is formed of bone material selected from the group consisting of cortical, cancellous; allograft, autograft, xenograft, demineralized or partially demineralized bone.

146. The intervertebral disc according to any one of the preceding claims 127 -145, further comprising migration-resistant structures disposed on at least one of the first and second outer surfaces.

147. The intervertebral disc according to any one of the preceding claims 127 -146, further comprising permanent fixation means disposed an at least one of the first and second outer surfaces.

148. The intervertebral disc according to any one of the preceding claims 127 -147, further comprising implant instrumentation attachment, guiding, or retaining structures diseased on at least one of the first and second inner or outer surfaces.