Artificial spinal fusion implants

• US 5,776,199 A
• Filed: 05/02/1997
• Issued: 07/07/1998
• Est. Priority Date: 06/28/1988
• Status: Expired due to Fees

• Current Assignee: Warsaw Orthopedic Incorporated (Medtronic Plc)
• Original Assignee: Sofamor Danek Properties, Inc. (Medtronic Plc)
• Inventors: Michelson, Gary Karlin
• Primary Examiner(s): SHAY, RANDY CITRIN
• Application Number:
  US08/850,654
• Time in Patent Office: 431 Days
• Field of Search: 623/11, 623/16, 623/17, 623/66, 606/61, 606/99, 128/69, 604/93, 604/890.1, 604/891.1, 604/892
• US Class Current: 623/17.16
• CPC Class Codes: A61F 2/30744 End caps, e.g. for closing an endoprosthetic cavity
• CPC Class Codes: A61F 2/30767 Special external or bone-contacting surface, e.g. coating for improving bone ingrowth
• CPC Class Codes: A61F 2/44 for the spine, e.g. vertebrae, spinal discs
• CPC Class Codes: A61F 2/442 Intervertebral or spinal discs, e.g. resilient non-disc-shaped intervertebral inflatable pockets A61F2/441; non-disc-shaped intervertebral fusion implants A61F2/4455
• CPC Class Codes: A61F 2/4455 for the fusion of spinal bodies, e.g. intervertebral fusion of adjacent spinal bodies, e.g. fusion cages intervertebral discs A61F2/442
• CPC Class Codes: A61F 2/447 substantially parallelepipedal, e.g. having a rectangular or trapezoidal cross-section
• CPC Class Codes: A61F 2/4611 of spinal prostheses
• CPC Class Codes: A61F 2002/2835 Bone graft implants for filling a bony defect or an endoprosthesis cavity, e.g. by synthetic material or biological material
• CPC Class Codes: A61F 2002/30062 (bio)absorbable, biodegradable, bioerodable, (bio)resorbable, resorptive
• CPC Class Codes: A61F 2002/30143 hexagonal
• CPC Class Codes: A61F 2002/30153 rectangular
• CPC Class Codes: A61F 2002/30158 trapezoidal
• CPC Class Codes: A61F 2002/30261 parallelepipedal
• CPC Class Codes: A61F 2002/3037 Translation along the common longitudinal axis, e.g. piston
• CPC Class Codes: A61F 2002/30398 Sliding
• CPC Class Codes: A61F 2002/30405 made by screwing complementary threads machined on the parts themselves
• CPC Class Codes: A61F 2002/30433 using additional screws, bolts, dowels, rivets or washers e.g. connecting screws
• CPC Class Codes: A61F 2002/30507 using a threaded locking member, e.g. a locking screw or a set screw
• CPC Class Codes: A61F 2002/30523 by means of meshing gear teeth
• CPC Class Codes: A61F 2002/30556 for adjusting thickness
• CPC Class Codes: A61F 2002/30579 : with mechanically expandable devices, e.g. fixation devices
• CPC Class Codes: A61F 2002/30593 : hollow
• CPC Class Codes: A61F 2002/30599 : stackable
• CPC Class Codes: A61F 2002/30604 : modular
• CPC Class Codes: A61F 2002/30774 : internally-threaded
• CPC Class Codes: A61F 2002/30777 : Oblong apertures
• CPC Class Codes: A61F 2002/30785 : parallel
• CPC Class Codes: A61F 2002/30787 : inclined obliquely with respect to each other
• CPC Class Codes: A61F 2002/30789 : perpendicular with respect to each other
• CPC Class Codes: A61F 2002/30797 : internally-threaded
• CPC Class Codes: A61F 2002/30836 : knurled
• CPC Class Codes: A61F 2002/30841 : Sharp anchoring protrusions for impaction into the bone, e.g. sharp pins, spikes
• CPC Class Codes: A61F 2002/30843 : Pyramidally-shaped
• CPC Class Codes: A61F 2002/30904 : serrated profile, i.e. saw-toothed
• CPC Class Codes: A61F 2002/3092 : having an open-celled or open-pored structure
• CPC Class Codes: A61F 2002/448 : comprising multiple adjacent spinal implants within the same intervertebral space or within the same vertebra, e.g. comprising two adjacent spinal implants
• CPC Class Codes: A61F 2002/4485 : comprising three or more adjacent spinal implants
• CPC Class Codes: A61F 2002/449 : comprising multiple spinal implants located in different intervertebral spaces or in different vertebrae
• CPC Class Codes: A61F 2002/4627 : with linear motion along or rotating motion about the instrument axis or the implantation direction, e.g. telescopic, along a guiding rod, screwing inside the instrument
• CPC Class Codes: A61F 2002/4629 : connected to the endoprosthesis or implant via a threaded connection
• CPC Class Codes: A61F 2210/0004 : bioabsorbable
• CPC Class Codes: A61F 2220/0025 : Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
• CPC Class Codes: A61F 2220/0033 : made by longitudinally pushing a protrusion into a complementary-shaped recess, e.g. held by friction fit
• CPC Class Codes: A61F 2220/0041 : using additional screws, bolts, dowels or rivets, e.g. connecting screws
• CPC Class Codes: A61F 2230/0017 : Angular shapes
• CPC Class Codes: A61F 2230/0019 : rectangular
• CPC Class Codes: A61F 2230/0026 : trapezoidal
• CPC Class Codes: A61F 2230/0082 : parallelepipedal
• CPC Class Codes: A61F 2250/0009 : for adjusting thickness
• CPC Class Codes: A61F 2250/0063 : Nested prosthetic parts
• CPC Class Codes: A61F 2310/00796 : Coating or prosthesis-covering structure made of a phosphorus-containing compound, e.g. hydroxy(l)apatite
• CPC Class Codes: Y10S 606/907 : Composed of particular material or coated

Abstract

A spinal implant for promoting fusion between adjacent vertebrae consisting of an integral, generally rectangular member having a plurality of openings for promoting ingrowth. In the preferred embodiment, the implant has an interior enclosed chamber, accessible from the outside through an opening in one wall, and a cap for covering said opening in the wall.

Claims

1. An implant for fusion of two adjacent vertebrae in the human spine after removal of disc material between endplates of the adjacent vertebrae, said implant comprising:

upper and lower walls and opposite side walls between said upper and lower walls,

said upper and lower walls having opposite surfaces configured to bear against and support a substantial portion of the endplates of the adjacent vertebrae,

said implant having a plurality of openings therethrough defined in at least said upper and lower walls, said openings being sized to permit fusion bone growth in continuity through said implant between the vertebral endplates,

said implant having a height substantially equal to the height of the space created by the removal of disc material from between the adjacent vertebrae and sized and shaped to be wholly contained within the space.

2. The implant of claim 1 further comprising:

a front wall and an opposite rear wall disposed between said upper and lower walls and said side walls.

3. The implant of claim 2, wherein said implant has a depth between said from wall and said rear wall, said depth being substantially the same as the depth between the adjacent vertebrae of the space created by removal of disc material.

4. The implant of claim 2, wherein said front wall is curved from one of said side walls to the other.

5. The implant of claim 4, wherein said front wall is convexly curved.

6. The implant of claim 2, wherein at least a portion of said rear wall is tapered to facilitate insertion of said implants to the disc space.

7. The implant of claim 2, wherein said rear wall is curved from one of said side walls to the other.

8. The implant of claim 2, wherein said front wall includes driving engaging means for engaging a driving instrument for placing said implant within the disc space between the adjacent vertebrae.

9. The implant of claim 8, wherein said driving engaging means includes a depression defined in said rear wall.

10. The implant of claim 2 wherein at least one of said front wall and said rear wall includes a plurality of openings therethrough.

11. The implant of claim 2, wherein said side walls are rounded adjacent said front wall for facilitating insertion of said implant.

12. The implant of claim 2, wherein said walls define an interior chamber for containing fusion bone growth material.

13. The implant of claim 12, wherein said upper wall defines an access opening therethrough communicating with said interior chamber, said access opening being substantially larger than any of said plurality of openings.

14. The implant of claim 13, further comprising a cap sized to engage and close said access opening.

15. The implant of claim 14, wherein said cap defines a number of openings therethrough in communication with said interior chamber when said cap closes said access opening.

16. The implant of claim 12, wherein at least one of said plurality of openings in each of said upper and lower walls communicates with said interior chamber.

17. The implant of claim 1, wherein said rear wall is convexly curved.

18. The implant of claim 1, wherein said implant has a width between said side wall, said width being substantially equal to the transverse width of the space created by the removed disc material.

19. The implant of claim 1, wherein said implant has a width between said side walls, said width being greater than said height of said implant.

20. The implant of claim 1, wherein said implant has a width between said side walls, said width being less than said height of said implant.

21. The implant of claim 1, wherein said side walls are flat and are substantially parallel to each other.

22. The implant of claim 1, wherein said side walls include openings defined therethrough.

23. The implant of claim 1, wherein at least some of said plurality of openings in said upper and lower walls form a number of channels through said implant.

24. The implant of claim 1, wherein said implant is substantially rectangular.

25. The implant of claim 1, wherein said implant is made at least in part of a metal suitable for surgical implantation.

26. The implant of claim 1, wherein at least some of said plurality of openings have a diameter of approximately 1 mm-3 mm.

27. The implant of claim 1, wherein at least a portion of said walls is treated to promote bone ingrowth.

28. The implant of claim 1, wherein at least one of said upper and lower walls includes bone engaging means for engaging said implant to at least one of the adjacent vertebrae while fusion occurs.

29. The implant of claim 28, wherein said bone engaging means includes an irregular surface.

30. The implant of claim 29, wherein said irregular surface includes a plurality of ridges.

31. The implant of claim 30, wherein said ridges are ratchetings facing the same direction to prevent expulsion of said implant in said same direction.

32. The implant of claim 30, wherein said bone engaging means includes ridges defined on both said top and said bottom walls.

35. The implant of claim 1, wherein said implant includes a rounded end between said upper and lower walls to facilitate insertion of said implant between the adjacent vertebrae.

38. The implant of claim 10 in which said plurality of openings are smaller than said access opening.

33. The implant of claim 33, wherein said ridges on at least one of said top and bottom surfaces are ratchetings facing one direction to prevent expulsion of said implant in said one direction.

34. The implant of claim 33, wherein said ridges on said top surface are ratchetings facing said one direction and said ridges on said bottom surface are ratchetings facing a direction opposite said one direction.

36. A spinal implant for fusion of two adjacent vertebrae in a human after removal of disc material between vertebral endplates of the adjacent vertebrae, said implant comprising:

upper and lower walls a front wall and an opposite rear wall between said upper and lower walls and side walls between said upper and lower walls and said front and rear walls,

said implant having a height between said upper and lower walls substantially equal to the height of the space created by removal of disc material between the adjacent vertebrae and sized and shaped to be wholly contained within the space,

a plurality of openings defined in each of at least said upper and lower walls,

said upper and lower walls defining substantially planar surfaces configured to bear against the vertebral endplates, and

a hollow interior chamber enclosed by said walls in communication with said plurality of openings and accessible through an access opening defined in one of said walls, said interior chamber being larger than any of said plurality of openings and sized to contain fusion promoting material,

said plurality of openings sized to permit fusion bone growth in continuity through said implant between the endplates of the adjacent vertebrae and with the fusion promoting material that may be contained within said interior chamber.

37. The spinal implant of claim 36, wherein said access opening is larger than any of said plurality of openings.

39. The spinal implant of claim 36, further comprising a cap sized to engage and close said access opening.

40. The spinal implant of claim 39 wherein said cap defines a number of openings therethrough in communication with said interior chamber when said cap closes said access opening.

41. The spinal implant of claim 39 further comprising a threaded engagement between said cap and said access opening.

42. The spinal implant of claim 41 wherein said cap defines a tool opening for receiving a tool to thread said cap into said access opening.

43. An interspace fusion implant for fusion of two adjacent vertebrae in the human spine after removal of disc material between endplates of the adjacent vertebrae said implant comprising:

a load bearing structure formed of a material that is stronger than bone, said structure sized and shaped to be wholly contained within the space left after removal of the disc material and including opposite upper and lower walls having opposite surfaces configured to bear against a substantial portion of the endplates of the adjacent vertebrae, said load bearing structure having a height between said upper and lower walls that is substantially equal to the height of the space created by the removal of the disc material; and

a plurality of openings defined in each of said upper and lower walls, said plurality of openings being sized and arranged to permit fusion bone growth in continuity between at least several of said plurality of openings in said upper wall and at least several of said plurality of openings in said lower wall.

44. The interspace fusion implant of claim 43, wherein said load bearing structure further defines an interior chamber in communication with each of said plurality of openings in each of said upper and lower walls.

45. The interspace fusion implant of claim 44, wherein:

said upper wall defines an access opening therethrough in communication with said interior chamber; and

said implant further comprises a cap for engaging and closing said access opening.

46. The interspace fusion implant of claim 45, wherein said cap defines at least one opening therethrough in communication with said interior chamber when said cap closes said access opening.

47. The interspace fusion implant of claim 43, wherein at least said opposite surfaces of said upper and lower walls are treated with a material to promote bone ingrowth into said opposite surfaces.

48. The interspace fusion implant of claim 43, wherein said load bearing structure includes opposite side walls between said upper and lower walls, each of said side walls defining a number of openings therethrough.

49. The interspace fusion implant of claim 43, wherein said load bearing structure includes opposite end walls between said upper and lower walls, at least one of said end walls being convexly curved.

50. The interspace fusion implant of claim 43, wherein said load bearing structure includes opposite end walls between said upper and lower walls, at least one of said end walls being rounded to facilitate insertion of the implant between the adjacent vertebrae.