Method for inserting a spinal implant

• US 6,224,595 B1
• Filed: 04/20/1998
• Issued: 05/01/2001
• Est. Priority Date: 02/17/1995
• Status: Expired due to Fees

• Current Assignee: Warsaw Orthopedic Incorporated (Medtronic Plc)
• Original Assignee: Sofamor Danek Holdings, Inc
• Inventors: Michelson, Gary Karlin
• Primary Examiner(s): Brown, Michael A.
• Application Number:
  US09/062,749
• Time in Patent Office: 1,107 Days
• Field of Search: 606/60, 606/61, 606/72, 606/73, 606/74, 606/86-88, 623/16, 623/17, 408/222, 470/198
• US Class Current: 606/86.00A
• CPC Class Codes: A61B 17/1671 for the spine
• CPC Class Codes: A61B 17/1757 for the spine
• CPC Class Codes: A61B 17/8888 at its central region
• CPC Class Codes: A61B 2017/0256 for the spine
• CPC Class Codes: A61B 2090/036 abutting on tissue or skin
• 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 2/30771 applied in original prostheses, e.g. holes or grooves
• 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 2/446 having a circular or elliptical cross-section substantially parallel to the axis of the spine, e.g. cylinders or frustocones
• CPC Class Codes: A61F 2/4603 for insertion or extraction of endoprosthetic joints or of accessories thereof
• CPC Class Codes: A61F 2/4611 of spinal prostheses
• CPC Class Codes: A61F 2/4657 Measuring instruments used for implanting artificial joints for surgical instruments A61B90/06
• 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 2002/3013 figure-"8"- or hourglass-shaped
• CPC Class Codes: A61F 2002/30131 horseshoe- or crescent- or C-shaped or U-shaped
• CPC Class Codes: A61F 2002/30143 hexagonal
• CPC Class Codes: A61F 2002/30148 lozenge- or diamond-shaped
• CPC Class Codes: A61F 2002/30235 tubular, e.g. sleeves
• CPC Class Codes: A61F 2002/30405 : made by screwing complementary threads machined on the parts themselves
• CPC Class Codes: A61F 2002/30593 : hollow
• 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 2002/30795 : Blind bores, e.g. of circular cross-section
• CPC Class Codes: A61F 2002/30797 : internally-threaded
• CPC Class Codes: A61F 2002/30836 : knurled
• CPC Class Codes: A61F 2002/3085 : with a threaded, e.g. self-tapping, bone-engaging surface, e.g. external surface
• CPC Class Codes: A61F 2002/30879 : Ribs
• CPC Class Codes: A61F 2002/30904 : serrated profile, i.e. saw-toothed
• CPC Class Codes: A61F 2002/30906 : shot- sand- or grit-blasted
• 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 2002/449 : comprising multiple spinal implants located in different intervertebral spaces or in different vertebrae
• CPC Class Codes: A61F 2002/4619 : for extraction
• 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 2002/4681 : by applying mechanical shocks, e.g. by hammering
• CPC Class Codes: A61F 2220/0025 : Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
• CPC Class Codes: A61F 2230/001 : Figure-8-shaped, e.g. hourglass-shaped
• CPC Class Codes: A61F 2230/0013 : Horseshoe-shaped, e.g. crescent-shaped, C-shaped, U-shaped
• CPC Class Codes: A61F 2230/0017 : Angular shapes
• CPC Class Codes: A61F 2230/0069 : cylindrical
• CPC Class Codes: A61F 2250/0063 : Nested prosthetic parts
• CPC Class Codes: A61F 2310/00023 : Titanium or titanium-based alloys, e.g. Ti-Ni alloys
• CPC Class Codes: A61F 2310/00293 : containing a phosphorus-containing compound, e.g. apatite
• CPC Class Codes: A61F 2310/00796 : Coating or prosthesis-covering structure made of a phosphorus-containing compound, e.g. hydroxy(l)apatite

Abstract

An artificial spinal implant is disclosed which when placed between two adjacent vertebrae directly participates and is incorporated in the ensuing fusion. Instrumentation and procedure is also disclosed.

Claims

1. A method for preparing two adjacent vertebrae and a disc space therebetween to receive at least one implant, the method consisting essentially of the steps of:

positioning one end of a hollow guard in contact with the adjacent vertebrae;

removing, through said hollow guard, bone from the adjacent vertebrae to form an opening across the disc space and into a portion of each of the two adjacent vertebrae; and

inserting said implant having a height greater than the normal height of the disc space through said hollow guard and into the opening.

2. The method of claim 1, wherein the positioning step includes the step of engaging said one end of said hollow guard to the two adjacent vertebrae.

3. The method of claim 1, wherein the removing step includes the substep of milling the opening.

4. The method of claim 1, wherein the removing step includes the substep of drilling the opening.

5. The method of claim 1, wherein the inserting step includes the substep of screwing said implant into the opening through said hollow guard.

6. The method of claim 1, wherein the inserting step includes inserting said implant comprising a fusion-promoting substance.

7. The method of claim 1, further comprising the step of loading said implant with fusion-promoting material prior to the step of inserting.

8. The method of claim 1, wherein the positioning step includes the substep of positioning said guard having at least two projections extending distally from a distal end of said guard, said distal end adapted to contact each of the vertebrae adjacent the disc space to be fused, said at least two projections adapted to penetrate the disc space so as to be located at least in part between the endplates of the vertebrae.

9. The method of claim 1, wherein the positioning step includes the step of positioning one end of a guard in contact with the adjacent vertebrae of the posterior lumbar spine, said guard for providing protected access to the spinal disc and the adjacent vertebrae to prepare across the spinal disc and into the adjacent vertebrae the implantation space and to insert into the implantation space said spinal implant through said guard, said guard having a passage through which said spinal implant passes into the implantation space in the spine, said guard having a distal end configured to be placed against the adjacent vertebrae, said distal end having a first portion adapted to be placed in contact with one of the adjacent vertebrae and a second portion adapted to be placed in contact with the other of the adjacent vertebrae, said first and second portions having a fixed height therebetween.

10. The method of claim 1, wherein the method is performed without distracting the adjacent vertebrae between the removing step and the inserting step.

11. The method of claim 1, wherein the method is performed without removing the hollow guard between the positioning step and the inserting step.

12. A method for preparing two adjacent vertebrae and a disc space therebetween to receive at least one implant, the method consisting essentially of the steps of:

positioning one end of a hollow guard in contact with the adjacent vertebrae;

forming, through said hollow guard, an opening across the disc space and into a portion of each of the two adjacent vertebrae, said opening having at least one arcuate portion extending into at least one of the adjacent vertebrae; and

inserting said implant through said hollow guard and into the opening.

13. The method of claim 12, wherein the positioning step includes the step of engaging said one end of said hollow guard to the two adjacent vertebrae.

14. The method of claim 12, wherein the forming step includes the substep of milling the opening.

15. The method of claim 12, wherein the forming step includes the substep of drilling the opening.

16. The method of claim 12, wherein the inserting step includes the substep of screwing said implant into the opening through said hollow guard.

17. The method of claim 12, wherein the inserting step includes inserting said implant comprising a fusion-promoting substance.

18. The method of claim 12, further comprising the step of loading said implant with fusion-promoting material prior to the step of inserting.

19. The method of claim 12, wherein the positioning step includes the substep of positioning said guard having at least two projections extending distally from a distal end of said guard, said distal end adapted to contact each of the vertebrae adjacent the disc space to be fused, said at least two projections adapted to penetrate the disc space so as to be located at least in part between the endplates of said vertebrae.

20. The method of claim 12, wherein the positioning step includes the step of positioning one end of a guard in contact with the adjacent vertebrae of the posterior lumbar spine, said guard for providing protected access to the spinal disc and the adjacent vertebrae to prepare across the spinal disc and into the adjacent vertebrae the implantation space and to insert into the implantation space said spinal implant through said guard, said guard having a passage through which said spinal implant passes into the implantation space in the spine, said guard having a distal end configured to be placed against the adjacent vertebrae, said distal end having a first portion adapted to be placed in contact with one of the adjacent vertebrae and a second portion adapted to be placed in contact with the other of the adjacent vertebrae, said first and second portions having a fixed height therebetween.

21. The method of claim 12, wherein the method is performed without distracting the adjacent vertebrae between the forming step and the inserting step.

22. The method of claim 12, wherein the method is performed without removing the hollow guard between the positioning step and the inserting step.

23. A method for preparing two adjacent vertebrae and a disc space therebetween to receive at least one implant, the method comprising the steps of:

positioning one end of a hollow guard in contact with the adjacent vertebrae;

removing, through said hollow guard, bone from the adjacent vertebrae to form an opening across the disc space and into a portion of each of the two adjacent vertebrae; and

inserting said implant having a height greater than the normal height of the disc space through said hollow guard and into the opening, the method being performed without distracting the adjacent vertebrae between the removing step and the inserting step.

24. The method of claim 23, further comprising the step of providing a spinal fusion implant of a material suitable for human implantation having a height along the longitudinal axis of the spine greater than the height of the implantation space comprising upper and lower portions adapted for placement in contact each of the adjacent vertebrae when inserted in the implantation space, each of said upper and lower portions having at least one opening adapted for placement in contact with the adjacent vertebrae, respectively, said openings of said upper and lower portions being in communication with one another and adapted for permitting for the growth of bone from adjacent vertebra to adjacent vertebra through said implant;

and

wherein the positioning step includes the step of positioning one end of a guard in contact with the adjacent vertebrae of the posterior lumbar spine, said guard for providing protected access to the spinal disc and the adjacent vertebrae to prepare across the spinal disc and into the adjacent vertebrae the implantation space and to insert into the implantation space said spinal implant through said guard, said guard having a passage through which said spinal implant passes into the implantation space in the spine, said guard having a distal end configured to be placed against the adjacent vertebrae, said distal end having a first portion adapted to be placed in contact with one of the adjacent vertebrae and a second portion adapted to be placed in contact with the other of the adjacent vertebrae, said first and second portions having a fixed height therebetween.

25. The method of claim 24, wherein the providing step includes the substep of providing said implant having at least a portion of said upper and lower portions that are arcuate along at least a portion of the length of said implant.

26. The method of claim 25, wherein the providing step includes the substep of providing said implant further comprising a hollow between said upper and lower arcuate portions of said implant for holding bone growth promoting material, said at least one opening of each of said upper and lower portions of said implant are in communication with said hollow to permit bone from adjacent vertebrae to grow through said implant.

27. The method of claim 26, further comprising the step of loading said hollow interior of said implant with fusion promoting substances.

28. The method of claim 27, wherein the loading step includes the substep of loading said hollow interior of said implant with bone.

29. The method of claim 26, wherein the providing step includes the substep of providing said implant having at least one of an insertion end and a trailing end that is open and adapted for loading bone growth promoting substances into said hollow.

30. The method of claim 29, further comprising the step of engaging an end cap for closing said open end of said implant.

31. The method of claim 24, wherein the providing step includes the substep of providing said implant that is comprised at least in part of an implant material other than bone.

32. The method of claim 24, wherein the providing step includes the substep of providing said implant having said upper and lower portions having at least one protrusion on said upper and lower portions for engaging the adjacent vertebrae.

33. The method of claim 32, wherein said protrusion is at least a portion of a thread.

34. The method of claim 24, wherein the positioning step includes the substep of positioning said guard having projections projecting distally from said distal end for penetrably engaging the posterior surface of each of the adjacent vertebrae.

35. The method of claim 34, wherein said projections extend at least in part into the disc space.

36. The method of claim 34, wherein the positioning step includes the substep of positioning said guard further comprising a wall surrounding said passage, said projections being coextensive with said wall.

37. The method of claim 34, wherein the positioning step includes the substep of positioning said guard having at least two projections extending distally from said distal end of said guard, said distal end adapted to contact each of the vertebrae adjacent the disc space to be fused, said at least two projections adapted to penetrate the disc space so as to be located at least in part between the endplates of said vertebrae.

38. The method of claim 37, wherein said projections are at least in part co-linear with an outer perimeter of said guard.

39. The method of claim 38, wherein said projections are teeth.

40. The method of claim 37, wherein said projections are teeth being at least in part co-linear with an outer perimeter of said guard.

41. The method of claim 24, wherein the positioning step includes the substep of positioning said guard that is a tubular sleeve that is at least in part hollow.

42. The method of claim 24, wherein the positioning step includes the substep of positioning said guard having a length defined by a distal portion and a proximal portion forming said length, said guard having a substantially uniform cross section along its distal portion.

43. The method of claim 24, wherein the positioning step includes the substep of positioning said guard having a substantially uniform cross section along its length.

44. The method of claim 43, wherein said distal end of said guard has a cross sectional configuration substantially the same as said substantially uniform cross section of said guard.

45. The method of claim 24, wherein the positioning step includes the substep of positioning said guard having a distal end having a circumference that is uninterrupted and constant.

46. The method of claim 45, further comprising projections extending from said uninterrupted and constant circumference of said distal end of said guard for engaging the spine.

47. The method of claim 46, wherein said projections penetrate the disc space.

48. The method of claim 24, wherein the positioning step includes the substep of positioning said guard having a width measured perpendicular to its height, the width of said guard when appropriately selected being less than one half of the width of the disc space.

49. The method of claim 24, further comprising the step of tapping the opening through said hollow guard.

50. The method of claim 24, wherein the inserting step includes the substep of screwing said implant into the opening through said hollow guard.

51. The method of claim 24, wherein the providing step includes the substep of providing said implant having at least one of an insertion end and a trailing end, said trailing end being adapted to cooperatively engage a driver for inserting said implant through said hollow guard and into the opening.

52. The method of claim 23, wherein the positioning step includes the substep of positioning said guard having projections projecting distally from a distal end for penetrably engaging the surface of each of the adjacent vertebrae.

53. The method of claim 52, wherein said projections extend at least in part into the disc space.

54. The method of claim 52, wherein the positioning step includes the substep of positioning said guard further comprising a wall surrounding a passage, said projections being coextensive with said wall.

55. The method of claim 52, wherein the positioning step includes the substep of positioning said guard having at least two projections extending distally from a distal end of said guard, said distal end adapted to contact each of the vertebrae adjacent the disc space to be fused, said at least two projections adapted to penetrate the disc space so as to be located at least in part between the endplates of the vertebrae.

56. The method of claim 23, wherein the method is performed without removing the hollow guard between the positioning step and the inserting step.

57. A method for preparing two adjacent vertebrae and a disc space therebetween to receive at least one implant, the method comprising the steps of:

positioning one end of a hollow guard in contact with the adjacent vertebrae;

forming, through said hollow guard, an opening across the disc space and into a portion of each of the two adjacent vertebrae, said opening having at least one arcuate portion extending into at least one of the adjacent vertebrae; and

inserting said implant through said hollow guard and into the opening, the method being performed without distracting the adjacent vertebrae between the removing step and the inserting step.

58. The method of claim 57, wherein the positioning step includes the substep of positioning said guard having at least two projections extending distally from a distal end of said guard, said distal end adapted to contact each of the vertebrae adjacent the disc space to be fused, said at least two projections adapted to penetrate the disc space so as to be located at least in part between the endplates of said vertebrae.

59. The method of claim 57, wherein the positioning step includes the step of positioning one end of said guard in contact with the adjacent vertebrae of the posterior lumbar spine, said guard for providing protected access to the spinal disc and the adjacent vertebrae to prepare across the spinal disc and into the adjacent vertebrae the implantation space and to insert into the implantation space said spinal implant through said guard, said guard having a passage through which said spinal implant passes into the implantation space in the spine, said guard having a distal end configured to be placed against the adjacent vertebrae, said distal end having a first portion adapted to be placed in contact with one of the adjacent vertebrae and a second portion adapted to be placed in contact with the other of the adjacent vertebrae, said first and second portions having a fixed height therebetween.

60. The method of claim 57, wherein the method is performed without removing said hollow guard between the positioning step and the inserting step.

61. A method for preparing two adjacent vertebrae and a disc space therebetween to receive at least one implant, the method comprising the steps of:

positioning one end of a hollow guard in contact with the adjacent vertebrae;

removing, through said hollow guard, bone from the adjacent vertebrae to form an opening across the disc space and into a portion of each of the two adjacent vertebrae; and

screwing said implant having an external thread and a height greater than the normal height of the disc space through said hollow guard and into the opening.

62. The method of claim 61, wherein the positioning step includes the substep of positioning said guard having at least two projections extending distally from a distal end of said guard, said distal end adapted to contact each of the vertebrae adjacent the disc space to be fused, said at least two projections adapted to penetrate the disc space so as to be located at least in part between the endplates of the vertebrae.

63. The method of claim 62, wherein the positioning step includes the step of positioning one end of said guard in contact with the adjacent vertebrae of the posterior lumbar spine, said guard for providing protected access to the spinal disc and the adjacent vertebrae to prepare across the spinal disc and into the adjacent vertebrae the implantation space and to insert into the implantation space said spinal implant through said guard, said guard having a passage through which said spinal implant passes into the implantation space in the spine, said guard having a distal end configured to be placed against the adjacent vertebrae, said distal end having a first portion adapted to be placed in contact with one of the adjacent vertebrae and a second portion adapted to be placed in contact with the other of the adjacent vertebrae, said first and second portions having a fixed height therebetween.

64. The method of claim 61, wherein the method is performed without distracting the adjacent vertebrae between the removing step and the inserting step.

65. The method of claim 61, wherein the method is performed without removing said guard between the positioning step and the screwing step.

66. A method for preparing two adjacent vertebrae and a disc space therebetween to receive an implant, the method comprising the steps of:

anchoring one end of a substantially tubular member against the two adjacent vertebrae so that at least a portion of said one end of said tubular member extends at least in part between the adjacent vertebrae and into the disc space;

forming through said tubular member, an opening across the disc space and into a portion of each of the two adjacent vertebrae;

tapping the opening to provide threads over at least a portion of the vertebrae; and

screwing said implant through said tubular member and into the opening.

67. The method of claim 66, further comprising the step of providing a spinal fusion implant of a material suitable for human implantation having a height along the longitudinal axis of the spine greater than the height of the implantation space, comprising upper and lower portions adapted for placement in contact with each of the adjacent vertebrae when inserted in the implantation space, each of said upper and lower portions having at least one opening adapted for placement in contact with the adjacent vertebrae, respectively, said openings of said upper and lower portions being in communication with one another and adapted for permitting for the growth of bone from adjacent vertebra to adjacent vertebra through said implant;

and

wherein the anchoring step includes the step of anchoring one end of said tubular member in contact with the adjacent vertebrae of the posterior lumbar spine, said tubular member for providing protected access to the spinal disc and the adjacent vertebrae to prepare across the spinal disc and into the adjacent vertebrae the implantation space and to insert into the implantation space said spinal implant through said tubular member, said tubular member having a passage through which said spinal implant passes into the implantation space in the spine, said tubular member having a distal end configured to be placed against the adjacent vertebrae, said distal end having a first portion adapted to be placed in contact with one of the adjacent vertebrae and a second portion adapted to be placed in contact with the other of the adjacent vertebrae, said first and second portions having a fixed height therebetween.

68. The method of claim 67, wherein the providing step includes the substep of providing said implant having at least a portion of said upper and lower portions that are arcuate along at least a portion of the length of said implant.

69. The method of claim 68, wherein the providing step includes the substep of providing said implant further comprising a hollow between said upper and lower arcuate portions of said implant for holding bone growth promoting material, said at least one opening of each of said upper and lower surfaces of said implant are in communication with said hollow to permit bone from adjacent vertebrae to grow through said implant.

70. The method of claim 69, further comprising the step of loading said hollow interior of said implant with fusion promoting substances.

71. The method of claim 70, wherein the loading step includes the substep of loading said hollow interior of said implant with bone.

72. The method of claim 71, wherein the anchoring step includes the substep of anchoring said tubular member that is a tubular sleeve that is at least in part hollow.

73. The method of claim 72, wherein the providing step includes the substep of providing said implant having at least one of an insertion end and a trailing end that is open and adapted for loading bone growth promoting substances into said hollow.

74. The method of claim 73, further comprising the step of engaging an end cap for closing said open end of said implant.

75. The method of claim 67, wherein the providing step includes the substep of providing said implant that is comprised at least in part of an implant material other than bone.

76. The method of claim 67, wherein the providing step includes the substep of providing said implant having said upper and lower portions having at least one protrusion on said upper and lower portions for engaging the adjacent vertebrae.

77. The method of claim 76, wherein said protrusion is at least a portion of a thread.

78. The method of claim 67, wherein the anchoring step includes the substep of anchoring said tubular member having projections projecting distally from said distal end for penetrably engaging the posterior surface of each of the adjacent vertebrae.

79. The method of claim 78, wherein said projections extend at least in part into the disc space.

80. The method of claim 78, wherein the anchoring step includes the substep of anchoring said tubular member further comprising a wall surrounding said passage, said projections being coextensive with said wall.

81. The method of claim 78, wherein the anchoring step includes the substep of anchoring said tubular member having at least two projections extending distally from said distal end of said tubular member, said distal end adapted to contact each of the vertebrae adjacent the disc space to be fused, said at least two projections adapted to penetrate the disc space so as to be located at least in part between the endplates of the vertebrae.

82. The method of claim 81, wherein said projections are at least in part co-linear with an outer perimeter of said tubular member.

83. The method of claim 82, wherein said projections are teeth.

84. The method of claim 81, wherein said projections are teeth being at least in part co-linear with an outer perimeter of said tubular member.

85. The method of claim 67, wherein the anchoring step includes the substep of anchoring said tubular member having a length defined by a distal portion and a proximal portion forming said length, said tubular member having a substantially uniform cross section along its distal portion.

86. The method of claim 67, wherein the anchoring step includes the substep of anchoring said tubular member having a substantially uniform cross section along its length.

87. The method of claim 86, wherein said distal end of said tubular member has a cross sectional configuration substantially the same as said substantially uniform cross-section of said tubular member.

88. The method of claim 67, wherein the anchoring step includes the substep of anchoring said tubular member having a distal end having a circumference that is uninterrupted and constant.

89. The method of claim 88, further comprising projections extending from said uninterrupted and constant circumference of said distal end of said tubular member for engaging the spine.

90. The method of claim 89, wherein said projections penetrate the disc space.

91. The method of claim 67, wherein the anchoring step includes the substep of anchoring said tubular member having a width measured perpendicular to its height, the width of said tubular member when appropriately selected being less than one half of the width of the disc space.

92. The method of claim 67, further comprising the step of tapping the opening through said hollow tubular member.

93. The method of claim 67, wherein the providing step includes the substep of providing said implant having at least one of an insertion end and a trailing end, said trailing end being adapted to cooperatively engage a driver for inserting said implant through said hollow tubular member and into the opening.

94. The method of claim 66, wherein the method is performed without removing said tubular member between the anchoring step and the screwing step.

95. A method for preparing two adjacent vertebrae and a disc space therebetween to receive at least one implant, the method comprising the steps of:

providing an implant of a material suitable for human implantation;

positioning one end of a tubular member in contact with the adjacent vertebrae;

forming, through said tubular member, an opening across the disc space and into a portion of each of the two adjacent vertebrae; and

inserting said implant through said tubular member and into the opening.

96. The method of claim 95, wherein the positioning step includes the substep of positioning said guard having at least two projections extending distally from a distal end of said guard, said distal end adapted to contact each of the vertebrae adjacent the disc space to be fused, said at least two projections adapted to penetrate the disc space so as to be located at least in part between the endplates of said vertebrae.

97. The method of claim 95, wherein the positioning step includes the step of positioning one end of a guard in contact with the adjacent vertebrae of the posterior lumbar spine, said guard for providing protected access to the spinal disc and the adjacent vertebrae to prepare across the spinal disc and into the adjacent vertebrae the implantation space and to insert into the implantation space said spinal implant through said guard, said guard having a passage through which said spinal implant passes into the implantation space in the spine, said guard having a distal end configured to be placed against the adjacent vertebrae, said distal end having a first portion adapted to be placed in contact with one of the adjacent vertebrae and a second portion adapted to be placed in contact with the other of the adjacent vertebrae, said first and second portions having a fixed height therebetween.

98. The method of claim 95, wherein the method is performed without distracting the adjacent vertebrae between the forming step and the inserting step.

99. The method of claim 95, wherein the method is performed without removing said tubular member between the positioning step and the inserting step.