Expandable push-in interbody spinal fusion implant

• US 6,716,247 B2
• Filed: 04/23/2002
• Issued: 04/06/2004
• Est. Priority Date: 02/04/2000
• Status: Expired due to Term

• Current Assignee: Warsaw Orthopedic Incorporated (Medtronic Plc)
• Original Assignee: Gary K. Michelson
• Inventors: Michelson, Gary K.
• Primary Examiner(s): McDermott, Corrine
• Assistant Examiner(s): Barrett, Thomas
• Application Number:
  US10/258,198
• Publication Number:
  US 20030208275A1
• Time in Patent Office: 714 Days
• Field of Search: 623/17-1-
• US Class Current: 623/17.16
• CPC Class Codes: A61B 17/8042 the additional component being a cover over the screw head
• CPC Class Codes: A61B 17/86 Pins or screws or threaded wires; nuts therefor A61B17/72 take precedence
• CPC Class Codes: A61F 2/28 Bones joints A61F2/30
• CPC Class Codes: A61F 2/30744 End caps, e.g. for closing an endoprosthetic cavity
• 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 2/446 having a circular or elliptical cross-section substantially parallel to the axis of the spine, e.g. cylinders or frustocones
• CPC Class Codes: A61F 2/4465 having a circular or kidney shaped cross-section substantially perpendicular to the axis of the spine
• CPC Class Codes: A61F 2/4611 of spinal prostheses
• CPC Class Codes: A61F 2002/2817 Bone stimulation by chemical reactions or by osteogenic or biological products for enhancing ossification, e.g. by bone morphogenetic or morphogenic proteins [BMP] or by transforming growth factors [TGF]
• 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 2002/30143 hexagonal
• CPC Class Codes: A61F 2002/30187 D-shaped or half-disc-shaped
• CPC Class Codes: A61F 2002/30261 parallelepipedal
• CPC Class Codes: A61F 2002/30331 made by longitudinally pushing a protrusion into a complementarily-shaped recess, e.g. held by friction fit
• CPC Class Codes: A61F 2002/30362 with possibility of relative movement between the protrusion and the recess
• CPC Class Codes: A61F 2002/30392 Rotation
• CPC Class Codes: A61F 2002/30405 made by screwing complementary threads machined on the parts themselves
• CPC Class Codes: A61F 2002/305 Snap connection
• CPC Class Codes: A61F 2002/30517 using a locking plate
• CPC Class Codes: A61F 2002/30538 : for adjusting angular orientation
• CPC Class Codes: A61F 2002/30556 : for adjusting thickness
• CPC Class Codes: A61F 2002/30593 : hollow
• CPC Class Codes: A61F 2002/30616 : Sets comprising a plurality of prosthetic parts of different sizes or orientations
• CPC Class Codes: A61F 2002/30624 : Hinged joint, e.g. with transverse axle restricting the movement
• CPC Class Codes: A61F 2002/30632 : with rotation-limiting stops, e.g. projections or recesses
• CPC Class Codes: A61F 2002/30774 : internally-threaded
• CPC Class Codes: A61F 2002/30777 : Oblong apertures
• CPC Class Codes: A61F 2002/30779 : arcuate
• 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 2002/3079 : Stepped or enlarged apertures, e.g. having discrete diameter changes
• 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 2002/30891 : Plurality of protrusions
• CPC Class Codes: A61F 2002/30904 : serrated profile, i.e. saw-toothed
• CPC Class Codes: A61F 2002/30975 : made of two halves
• 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 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 2230/0017 : Angular shapes
• CPC Class Codes: A61F 2230/0034 : D-shaped
• CPC Class Codes: A61F 2230/0082 : parallelepipedal
• CPC Class Codes: A61F 2250/0006 : for adjusting angular orientation
• CPC Class Codes: A61F 2250/0009 : for adjusting thickness
• CPC Class Codes: A61F 2310/00017 : Iron- or Fe-based alloys, e.g. stainless steel
• CPC Class Codes: A61F 2310/00023 : Titanium or titanium-based alloys, e.g. Ti-Ni alloys
• CPC Class Codes: A61F 2310/00071 : Nickel or Ni-based alloys
• CPC Class Codes: A61F 2310/00179 : Ceramics or ceramic-like structures
• CPC Class Codes: A61F 2310/00293 : containing a phosphorus-containing compound, e.g. apatite
• CPC Class Codes: A61F 2310/00359 : Bone or bony tissue
• CPC Class Codes: A61F 2310/00407 : Coating made of titanium or of Ti-based alloys
• CPC Class Codes: A61F 2310/00796 : Coating or prosthesis-covering structure made of a phosphorus-containing compound, e.g. hydroxy(l)apatite

Abstract

A push-in interbody spinal fusion (100) implant having an expandable height. The implant (100) comprises upper and lower members (102 and 106) with an expander in between (122). When the expander (122) is changed from one position to another, for example as in the first embodiment where it is rotated in a plane perpendicular to the axis of the upper and lower members (102 and 106), the height of the implant (100) is increased.

Claims

1. A push-in interbody spinal fusion implant for linear insertion at least in part across at least the height of a disc space between two adjacent vertebral bodies of a spine, said implant comprising:

an upper member having an upper surface adapted for placement toward and into contact with one of the adjacent vertebral bodies from within the disc space, said upper surface being non-arcuate along a substantial portion of the length of said implant, said upper surface having at least one opening therethrough and adapted to contact one of the adjacent vertebral bodies, said upper member having a proximal end and a distal end;

a lower member having a lower surface adapted for placement toward and into contact with the other of the adjacent vertebral bodies from within the disc space, said lower surface being non-arcuate along a substantial portion of the length of said implant, said lower surface having at least one opening therethrough and adapted to contact the other of the adjacent vertebral bodies, said openings of said upper and lower surfaces being in communication with one another and adapted for permitting for the growth of bone from adjacent vertebral body to adjacent vertebral body through said implant and being sufficiently sized and located to allow for interbody spinal fusion through said implant, said lower member having a proximal end and a distal end corresponding to said proximal end and said distal end of said upper member, respectively, and a length between said proximal and distal ends, said upper and lower members articulating therebetween adjacent one of said proximal ends and said distal ends of said upper and lower members and allowing for expansion of the height of said implant, said upper and lower members having a first position relative to one another allowing for a collapsed implant height and a second position relative to one another allowing for an increased height of at least a portion of said implant; and

a blocker pivotally attached to one of said upper and lower members proximate one of said proximal and distal ends and being adapted to pivot into cooperative engagement with another of said one of said upper and lower members, said blocker being adapted to hold at least a portion of said upper and lower members apart so as to maintain the increased height of said implant and resist the collapse of said implant to the collapsed implant height when said implant is in a final deployed position, said implant having a width and said blocker having a width less than the width of said implant.

2. The push-in implant of claim 1, further comprising a hollow defined between said upper and lower members in communication with said openings in each of said upper and lower surfaces, said hollow being adapted to receive fusion-promoting substances.

3. The push-in implant of claim 2, wherein said hollow has a width that is unobstructed by any mechanism for moving said blocker.

4. The push-in implant of claim 2, wherein said implant has a constant width in both the collapsed height and the increased height.

5. The push-in implant of claim 2, wherein said blocker is located at least in part between said upper and lower members.

6. The push-in implant of claim 2, wherein said blocker is pivotally attached to said proximate end, said blocker being configured to rotate towards said distal end.

7. The push-in implant of claim 2, wherein said blocker is a portion of one of said ends of said upper and lower members.

8. The push-in implant of claim 2, wherein said blocker is adapted to cooperatively engage a tool used to move said blocker from an initial position to a final position to increase the height of said implant, said tool not being a part of said implant and being removed from said implant after moving said blocker into the final position.

9. The push-in implant of claim 2, wherein said blocker has a width less than one half the width of said implant.

10. The push-in implant of claim 2, wherein said implant has side walls and said blocker does not contact said side walls when said implant is in the final deployed position.

11. The push-in implant of claim 2, wherein said blocker moves said upper and lower surfaces of said upper and lower members from a parallel orientation to an angled orientation relative to one another.

12. The push-in implant of claim 2, wherein at least one of said upper and lower members is configured to cooperate with a projection so as to stop said upper and lower members from being moved apart from one another more than a predetermined distance.

13. The push-in implant of claim 2, wherein said upper and lower members are configured to cooperate with one another so as to stop said upper and lower members from being moved apart from one another more than a predetermined distance.

14. The push-in implant of claim 2, wherein said upper and lower members have walls contacting one another.

15. The push-in implant of claim 14, wherein said walls are aligned parallel with the longitudinal axis of said implant.

16. The push-in implant of claim 14, wherein said walls are at least in part overlapping.

17. The push-in implant of claim 2, wherein said upper and lower members have a rotational articulation therebetween adjacent one of said proximal end and said distal end of said upper and lower members.

18. The push-in implant of claim 17, wherein said rotational articulation is at one of said proximal end and said distal end of said upper and lower members opposite said blocker.

19. The push-in implant of claim 17, wherein said rotational articulation allows for expansion.

20. The push-in implant of claim 19, wherein said rotational articulation allows for limited expansion.

21. The push-in implant of claim 17, wherein said rotational articulation is formed by said upper and lower members interdigitating so as to cooperatively engage.

22. The push-in implant of claim 21, wherein said rotational articulation is configured such that engagement occurs when said upper and lower members are substantially perpendicular to one another.

23. The push-in implant of claim 22, wherein said rotational articulation is configured to remain engaged within a range of movement of said upper and lower members resulting from positioning said implant in the second position.

24. The push-in implant of claim 2, wherein one of said upper and lower members has an interior wall, which is unexposed, extending therefrom toward the other of said upper and lower members when said implant is in an initial insertion position, and when said implant is in a final position said implant has a shape such that each of said upper and lower surfaces of said upper and lower members are separated by at least a portion of said interior wall, which now has an exposed side.

25. The push-in implant of claim 24, wherein said upper and lower members have side walls for engaging each other.

26. The push-in implant of claim 25, wherein said side walls of said upper and lower members are at least partially overlapping walls.

27. The push-in implant of claim 24, wherein said upper and lower surfaces of said upper and lower members form an angular orientation relative to one another when said implant is in the final position.

28. The push-in implant of claim 24, wherein said upper and lower surfaces of said upper and lower members are substantially planar and parallel when said implant is in the initial insertion position.

29. The push-in implant of claim 2, wherein said implant has an interior, at least one of said upper and lower surfaces has a screw hole passing therethrough adapted to receive a screw passing from said interior of said implant into one of the adjacent vertebral bodies.

30. The push-in implant of claim 29, wherein each of said upper and lower surfaces has at least one screw hole passing therethrough adapted to receive a screw passing from said interior of said implant into the adjacent vertebral body in contact with each of said upper and lower surfaces respectively.

31. The push-in implant of claim 29, further comprising at least one screw adapted to pass from said interior of said implant through said screw hole and into the adjacent vertebral body to anchor said implant to the adjacent vertebral body.

32. The push-in implant of claim 2, wherein said implant has a side surface when in a final position that is contoured to cooperate with another implant.

33. The push-in implant of claim 2, further comprising a cap for closing one of said proximal end and said distal end of said upper and lower members, said cap having an exterior surface and an interior surface.

34. The push-in implant of claim 33, wherein said interior surface of said cap has spaced slots about its circumference to facilitate a snap fit of said cap into said implant.

35. The push-in implant of claim 2, wherein said implant comprises an artificial material other than bone.

36. The push-in implant of claim 2, wherein said implant is made of an artificial material that is stronger than bone.

37. The push-in implant of claim 2, wherein said implant is made of an artificial material that is harder than bone.

38. The push-in implant of claim 2, wherein said implant comprises bone.

39. The push-in implant of claim 38, wherein said bone includes cortical bone.

40. The push-in implant of claim 2, wherein said implant comprises bone growth promoting material.

41. The push-in implant of claim 40, wherein said bone growth promoting material includes at least one of bone morphogenetic protein, hydroxyapatite, and genes coding for the production of bone.

42. The push-in implant of claim 2, wherein said implant is treated with a bone growth promoting substance.

43. The push-in implant of claim 2, wherein said implant is a source of osteogenesis.

44. The push-in implant of claim 2, wherein said implant is at least in part bioabsorbable.

45. The push-in implant of claim 2, wherein said implant comprises metal.

46. The push-in implant of claim 45, wherein said metal includes titanium.

47. The push-in implant of claim 2, wherein said implant comprises a plastic material.

48. The push-in implant of claim 2, wherein said implant comprises a ceramic material.

49. The push-in implant of claim 2, wherein said implant is formed of a porous material.

50. The push-in implant of claim 2, wherein said implant is formed of a material that intrinsically participates in the growth of bone from adjacent vertebral body to adjacent vertebral body through said implant.

51. The push-in implant of claim 2, wherein said fusion promoting substances include at least one of bone morphogenetic protein, hydroxyapatite, and genes coding for the production of bone.

52. The push-in implant of claim 2, wherein at least a portion of said implant is treated to promote bone ingrowth between said implant and said adjacent vertebral bodies.

53. The push-in implant of claim 2, in combination with a chemical substance to inhibit scar formation.

54. The push-in implant of claim 2, further comprising at least a portion of a bone-engaging projection adapted for linear insertion formed on the exterior of each of said upper and lower surfaces for penetrably engaging the adjacent vertebral bodies and to facilitate securing said implant into the spine.

55. The push-in implant of claim 54, wherein said bone-engaging projection is select from one of a ratchet, a surface roughening, and a knurling.

56. The push-in implant of claim 2, wherein said upper member has side walls extending from said upper surface toward said lower member.

57. The push-in implant of claim 2, wherein said lower member has side walls extending from said lower surface toward said upper member.

58. The push-in implant of claim 2, wherein said upper member has side walls extending from said upper surface toward said lower member and said lower member has side walls extending from said lower surface toward said upper member.

59. The push-in implant of claim 2, wherein said implant is substantially parallelepiped.

60. The push-in implant of claim 1, in combination with a fusion promoting substance.

61. The push-in implant of claim 60, wherein said fusion promoting substance includes at least one of bone, bone morphogenetic protein, hydroxyapatite, and genes coding for the production of bone.

62. The push-in implant of claim 1, in combination with a tool for expanding said implant.

63. The combination of claim 62, wherein said tool is one of a spreader and a distractor.

64. The push-in implant of claim 1, in combination with a tool for inserting said implant at least in part into the disc space.