Interbody spinal fusion implants

• US 6,758,849 B1
• Filed: 08/18/2000
• Issued: 07/06/2004
• Est. Priority Date: 02/17/1995
• Status: Expired due to Fees

• Current Assignee: Warsaw Orthopedic Incorporated (Medtronic Plc)
• Original Assignee: SDGI Holdings Incorporated (Medtronic Plc)
• Inventors: Michelson, Gary Karlin
• Primary Examiner(s): Brown, Michael A.
• Application Number:
  US09/641,865
• Time in Patent Office: 1,418 Days
• Field of Search: 606/60, 606/61, 623/17.1, 623/17.11, 623/16.1
• US Class Current: 606/247
• CPC Class Codes: A61B 17/8875 Screwdrivers, spanners or wrenches
• 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 2/442 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 2/4611 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 2002/30777 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 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

The present invention discloses a spinal fusion implant that is at least partially cylindrical, made of material appropriate for human implantation and having preferably, but not necessarily, one closed end and one end capable of being closed, such that an internal chamber can be filled and hold any natural or artificial osteoconductive, osteoinductive, osteogenic, or other fusion enhancing material. The partially cylindrical implant directly participates and is incorporated in the ensuing fusion. In the preferred embodiment, the implant of the present invention relies on surface roughenings of the outer surface to enhance its stability and resist dislodgement from within the disc space between two adjacent vertebrae. The implant of the present invention incorporates at its rear end, an engagement means to facilitate insertion or extraction of the implant. The implant may be filled with, coated with, and/or composed of, fusion promoting substances. Finally, the implant of the present invention does not require rotation for its insertion and can be seated by linear advancement.

Claims

1. A spinal fusion implant made of a material appropriate for human implantation into and across a disc space between two adjacent vertebral bodies, said implant comprising in combination:

a body having a non-threaded exterior with opposed rigid portions adapted to be oriented toward the adjacent endplates of the two adjacent vertebral bodies and having a distance therebetween defining an implant height greater than the normal height of the disc space to be fused, each of said opposed rigid portions having at least one opening passing therethrough to allow bone growth from one of the adjacent vertebral bodies through said implant to the other of the adjacent vertebral bodies, said body being formed of an implantation material other than bone; and

a fusion promoting substance comprising bone morphogenetic protein.

2. The spinal fusion implant of claim 1, further comprising a protrusion extending from each of said opposed rigid portions for engaging each of the adjacent vertebral bodies to maintain said implant within the disc space.

3. The spinal fusion implant of claim 2, wherein sold protrusion comprises a ridge.

4. The spinal fusion implant of claim 2, wherein said protrusion comprises a ratcheting.

5. The spinal fusion implant of claim 1, further comprising a plurality of ratchetings facing the same direction extending from each of said opposed rigid portions for engaging each of the adjacent vertebral bodies to maintain said implant within the disc space.

6. The spinal fusion implant of claim 1, further comprising a plurality of cells in said body for retaining said fusion promoting substance.

7. The spinal fusion implant of claim 1, wherein said opposed rigid portions have a porous surface.

8. The spinal fusion implant of claim 1, wherein said implantation material is porous.

9. The spinal fusion implant of claim 1, wherein said implant is treated with said fusion promoting substance.

10. The spinal fusion implant of claim 1, wherein said implant is coated with said fusion promoting substance.

11. The spinal fusion implant of claim 1, wherein said fusion promoting substance is contained within said implant.

12. The spinal fusion implant of claim 1, wherein said opposed rigid portions have a bone ingrowth surface.

13. The spinal fusion implant of claim 1, wherein said implantation material is stronger than bone.

14. The spinal fusion implant of claim 1, wherein each of said opposed rigid portions comprises an interior surface, said interior surfaces being spaced apart to define a hollow interior in communication with said at least one opening of each of said opposed rigid portions.

15. The spinal fusion implant of claim 14, wherein said implant has a leading end for insertion into the spine and an opposite trailing end, at least one of said ends being open to allow access to said hollow interior.

16. The spinal fusion implant of claim 15, wherein said at least one end providing access to said hollow interior of said implant is adapted to be closed by a cap.

17. The spinal fusion implant of claim 16, wherein said implant having said at least one end providing access to said hollow interior is in combination with a cap adapted to close said hollow interior.

18. The spinal fusion implant of claim 1, in combination with bone.

19. The spinal fusion implant of claim 18, wherein said bone is compressively loaded in said implant.

20. The spinal fusion implant of claim 1, in combination with hydroxyapatite.

21. The spinal fusion implant of claim 1, wherein said opposed rigid portions are arcuate.

22. A spinal fusion implant made of a material appropriate for human implantation into and across a disc space between two adjacent vertebral bodies, said implant comprising in combination:

a body having a non-threaded exterior with opposed rigid arcuate portions adapted to be oriented toward the adjacent endplates of the two adjacent vertebral bodies, said opposed rigid arcuate portions having the same radius, each of said opposed rigid arcuate portions having at least one opening passing therethrough to allow bone growth from one of the adjacent vertebral bodies through said implant to the other of the adjacent vertebral bodies, said body being formed of an implantation material other than bone; and

a fusion promoting substance comprising bone morphogenetic protein.

23. The spinal fusion implant of claim 22, further comprising a protrusion extending from each of said opposed rigid portions for engaging each of the adjacent vertebral bodies to maintain said implant within the disc space.

24. The spinal fusion implant of claim 23, wherein said protrusion comprises a ridge.

25. The spinal fusion implant of claim 23, wherein said protrusion comprises a ratcheting.

26. The spinal fusion implant of claim 22, further comprising a plurality of ratchetings facing the same direction extending from each of said opposed rigid portions for engaging each of the adjacent vertebral bodies to maintain said implant within the disc space.

27. The spinal fusion implant of claim 22, further comprising a plurality of cells in said body for retaining said fusion promoting substance.

28. The spinal fusion implant of claim 22, wherein said opposed rigid portions have a porous surface.

29. The spinal fusion implant of claim 22, wherein said implantation material is porous.

30. The spinal fusion implant of claim 22, wherein said implant is treated with said fusion promoting substance.

31. The spinal fusion implant of claim 22, wherein said implant is coated with said fusion promoting substance.

32. The spinal fusion implant of claim 22, wherein said fusion promoting substance is contained within said implant.

33. The spinal fusion implant of claim 22, wherein said opposed rigid portions have a bone ingrowth surface.

34. The spinal fusion implant of claim 22, wherein said implantation material is stronger than bone.

35. The spinal fusion implant of claim 22, wherein each of said opposed rigid portions comprises an interior surface, said interior surfaces being spaced apart to define a hollow interior in communication with said at least one opening of each of said opposed portions.

36. The spinal fusion implant of claim 35, wherein said implant has a leading end for insertion into the spine and an opposite trailing end, at least one of said ends being open to allow access to said hollow interior.

37. The spinal fusion implant of claim 36, wherein said at least one end providing access to said hollow interior of said implant is adapted to be closed by a cap.

38. The spinal fusion implant of claim 37, wherein said implant having said at least one end providing access to said hollow interior is in combination with a cap adapted to close said hollow interior.

39. The spinal fusion implant of claim 22, in combination with bone.

40. The spinal fusion implant of claim 39, wherein said bone is compressively loaded in said implant.

41. The spinal fusion implant of claim 22, in combination with hydroxyapatite.

42. The spinal fusion implant of claim 22, wherein said implant has a height greater than the disc space between the two adjacent vertebral bodies to be fused.

43. A spinal fusion implant made of a material appropriate for human implantation into and across a disc space between two adjacent vertebral bodies, said implant comprising in combination:

a body having a non-threaded exterior with opposed rigid arcuate portions adapted to be oriented toward the adjacent endplates of the two adjacent vertebral bodies and having a distance therebetween defining an implant height greater than the normal height of the disc space to be fused, said opposed arcuate rigid portions having the same radius, each of said opposed arcuate portions having at least one opening passing the through to allow bone growth from one of the adjacent vertebral bodies through said implant to the other of the adjacent vertebral bodies;

a plurality of surface roughenings protruding from said exterior of said body adapted to engage the two adjacent vertebral bodies to maintain said implant in place, said surface roughenings configured to resist expulsion of said implant from between the two adjacent vertebral bodies, said body being formed of an implantation material other than bone; and

a fusion promoting substance comprising bone morphogenetic protein.

44. The spinal fusion implant of claim 43, wherein said surface roughenings include knurling.

45. The spinal fusion implant of claim 43, further comprising a protrusion extending from each of said opposed rigid portions for engaging each of the adjacent vertebral bodies to maintain said implant within the disc space.

46. The spinal fusion implant of claim 45, wherein said protrusion comprises a ridge.

47. The spinal fusion implant of claim 45, wherein said protrusion comprises a ratcheting.

48. The spinal fusion implant of claim 43, further comprising a plurality of ratchetings facing the same direction extending from each of said opposed rigid portions for engaging each of the adjacent vertebral bodies to maintain said implant within the disc space.

49. The spinal fusion implant of claim 43, further comprising a plurality of cells in said body for retaining said fusion promoting substance.

50. The spinal fusion implant of claim 43, wherein said opposed rigid portions have a porous surface.

51. The spinal fusion implant of claim 43, wherein said implantation material is porous.

52. The spinal fusion implant of claim 43, wherein said implant is treated with said fusion promoting substance.

53. The spinal fusion implant of claim 43, wherein said implant is coated with said fusion promoting substance.

54. The spinal fusion implant of claim 43, wherein said fusion promoting substance is contained within said implant.

55. The spinal fusion implant of claim 43, wherein said opposed rigid portions have a bone ingrowth surface.

56. The spinal fusion implant of claim 43, wherein said implantation material is stronger than bone.

57. The spinal fusion implant of claim 43, wherein each of said opposed rigid portions comprises an interior surface, said interior surfaces being spaced apart to define a hollow interior in communication with said at least one opening of each of said opposed portions.

58. The spinal fusion implant of claim 57, wherein said implant has a leading end for insertion into the spine and an opposite trailing end, at least one of said ends being open to allow access to said hollow interior.

59. The spinal fusion implant of claim 58, wherein said at least one end providing access to said hollow interior of said implant is adapted to be closed by a cap.

60. The spinal fusion implant of claim 59, wherein said implant having said at least one end providing access to said hollow interior is in combination with a cap adapted to close said hollow interior.

61. The spinal fusion implant of claim 43, in combination with bone.

62. The spinal fusion implant of claim 61, wherein said bone is compressively loaded in said implant.

63. The spinal fusion implant of claim 43, in combination with hydroxyapatite.

64. A spinal fusion implant made of a material appropriate for human implantation into and across a disc space between two adjacent vertebral bodies, said implant comprising:

a body having a non-threaded exterior with opposed rigid arcuate portions adapted to be oriented toward the adjacent endplates of the two adjacent vertebral bodies, each of said opposed arcuate portions having at least one opening passing therethrough to allow bone growth from one of the two adjacent vertebral bodies through said implant to the other of the two adjacent vertebral bodies;

a plurality of surface projections on said exterior of said body adapted to engage the vertebral bodies to maintain said implant in place; and

a fusion promoting substance comprising bone morphogenetic protein.

65. The spinal fusion implant of claim 64, wherein said surface projections include a plurality of annular ratchetings defined around said body to resist expulsion of said implant from between the adjacent vertebral bodies.

66. The spinal fusion implant of claim 64, wherein said projections comprise a ridge.

67. The spinal fusion implant of claim 64, wherein said projections comprise a ratcheting.

68. The spinal fusion implant of claim 67, wherein said ratchetings face the same direction and extend from each of said opposed portions for engaging each of the adjacent vertebral bodies to maintain said implant within the disc space.

69. The spinal fusion implant of claim 64, further comprising a plurality of cells in said body for retaining said fusion promoting substance.

70. The spinal fusion implant of claim 64, wherein said opposed portions have a porous surface.

71. The spinal fusion implant of claim 64, wherein said implantation material is porous.

72. The spinal fusion implant of claim 64, wherein said implant is treated with said fusion promoting substance.

73. The spinal fusion implant of claim 64, wherein solid implant is coated with said fusion promoting substance.

74. The spinal fusion implant of claim 64, wherein said fusion promoting substance is contained within said implant.

75. The spinal fusion implant of claim 64, wherein said opposed portions have a bone ingrowth surface.

76. The spinal fusion implant of claim 64, wherein said implantation material is stronger than bone.

77. The spinal fusion implant of claim 64, wherein each of said opposed portions comprises an interior surface, said interior surfaces being spaced apart to define a hollow interior in communication with said at least one opening of each of said opposed portions.

78. The spinal fusion implant of claim 77, wherein said implant has a leading end for insertion into the spine and an opposite trailing end, at least one of said ends being open to allow access to said hollow interior.

79. The spinal fusion implant of claim 78, wherein said at least one end providing access to said hollow interior of said implant is adapted to be closed by a cap.

80. The spinal fusion implant of claim 79, wherein said implant having said at least one end providing access to said hollow interior is in combination with a cap adapted to close said hollow interior.

81. The spinal fusion implant of claim 64, in combination with bone.

82. The spinal fusion implant of claim 81, wherein said bone is compressively loaded in said implant.

83. The spinal fusion implant of claim 64, in combination with hydroxyapatite.

84. The spinal fusion implant of claim 64, wherein said implant has a height greater than the disc space between the two adjacent vertebral bodies to be fused.