Intervertebral implant with movement resistant structure

• US 20040249377A1
• Filed: 08/05/2004
• Published: 12/09/2004
• Est. Priority Date: 07/12/2001
• Status: Active Grant

• Current Assignee: Warsaw Orthopedic Incorporated (Medtronic Plc)
• Original Assignee: Warsaw Orthopedic Incorporated (Medtronic Plc)
• Inventors: Kaes, David R., Morris, John W., Winterbottom, John, Geisler, Fred, Shimp, Lawrence A.
• Granted Patent: US 7,833,245 B2
• Time in Patent Office: Days
• US Class Current: 606/61
• 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 2/30965 Reinforcing the prosthesis by embedding particles or fibres during moulding or dipping
• 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 2002/2839 Bone plugs or bone graft dowels
• CPC Class Codes: A61F 2002/30057 made from both cortical and cancellous adjacent parts
• CPC Class Codes: A61F 2002/30059 differing in bone mineralization, e.g. made from both mineralized and demineralized adjacent parts
• CPC Class Codes: A61F 2002/30062 (bio)absorbable, biodegradable, bioerodable, (bio)resorbable, resorptive
• CPC Class Codes: A61F 2002/30131 horseshoe- or crescent- or C-shaped or U-shaped
• CPC Class Codes: A61F 2002/30176 V-shaped
• CPC Class Codes: A61F 2002/30354 Cylindrically-shaped protrusion and recess, e.g. cylinder of circular basis
• CPC Class Codes: A61F 2002/30405 made by screwing complementary threads machined on the parts themselves
• CPC Class Codes: A61F 2002/30492 using a locking pin
• CPC Class Codes: A61F 2002/30578 having apertures, e.g. for receiving fixation screws
• CPC Class Codes: A61F 2002/30593 hollow
• CPC Class Codes: A61F 2002/30677 Means for introducing or releasing pharmaceutical products, e.g. antibiotics, into the body
• CPC Class Codes: A61F 2002/30777 Oblong apertures
• CPC Class Codes: A61F 2002/30785 parallel
• 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 2002/3085 : with a threaded, e.g. self-tapping, bone-engaging surface, e.g. external surface
• CPC Class Codes: A61F 2002/30904 : serrated profile, i.e. saw-toothed
• CPC Class Codes: A61F 2002/449 : comprising multiple spinal implants located in different intervertebral spaces or in different vertebrae
• 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 2230/0013 : Horseshoe-shaped, e.g. crescent-shaped, C-shaped, U-shaped
• CPC Class Codes: A61F 2230/0054 : V-shaped
• 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 2310/00131 : Tantalum or Ta-based alloys
• CPC Class Codes: A61F 2310/00293 : containing a phosphorus-containing compound, e.g. apatite
• CPC Class Codes: A61F 2310/00365 : Proteins; Polypeptides; Degradation products thereof

Abstract

An implant unit used in surgery has a body made from osteogenic implantable material and including an implant portion and a retaining portion, which is coupled to and extends transversely to the implant portion. The retaining portion is attached to the sidewall of the adjoining vertebral body or mammal bone to prevent displacement of the implant portion relative to the vertebral body or mammal bone and to accelerate fusion therebetween.

Claims

1. An implant comprising a body made entirely from osteogenic implantable material and including an implant portion and a retaining portion coupled to and extending transversely to the implant portion.

2. The implant according to claim 1, wherein the retaining and implant portions are integrally coupled to one another to form a monolithic, one-piece body.

3. The implant according to claim 1, wherein the retaining and implant portions are detachably coupled.

4. The implant according to claim 1, wherein the osteogenic implantable material is selected from the group consisting of mammalian bone including bone particles, bone powder, bone chips, or a bone composite comprising the bone tissue distributed in a polymeric binder and least one biologically active component, medicinal agents and drugs and/or combinations thereof.

5. An implant unit for repairing a vertebral segment or segments or a bone repair site in mammalian comprising:

an implant portion extending in an insertion plane an juxtaposed with surfaces to be repaired; and

a retaining portion extending transversely to the insertion plane of the implant portion attachable to a sidewall of the at least one vertebral body or a mammalian bone, the retaining and implant portions being made of implantable material and being coupled to one another so that during the period of repair the remaining portion substantially prevents displacement of the implant relative to the surface to be repaired and to carry loads over the intervertebral space or the mammalian bone.

6. The implant unit according to claim 5, wherein the implantable material is osteogenic.

7. The implant unit according to claim 5, wherein at least one fastner extends through the retaining portion of the implant into the sidewall to secure the retaining portion to the sidewall.

8. The implant unit according to claim 6, wherein the implantable osteogenic material is obtained from bone tissue.

9. The implant unit according to claim 8, wherein the bone tissue is selected from the group consisting of bone particles, bone powder, bone chips, and/or a combination of these, and/or a bone composite comprising bone tissue distributed in a polymeric binder and may contain at least one biologically active component, medicinal agents and/or drugs.

10. The implant unit according to claim 9, wherein the bone tissue is selected from long mammalian bones containing a medullary canal defining an opening in the implant portion, the open space may be filled with material selected from demineralized bone powder and/or a cancellous bone plug.

11. The implant unit according to claim 9, wherein the implant portion has a continuous peripheral wall, which is provided with a polygonal shape or an annular shape, and/or a discontinuous C-shaped or V-shaped peripheral wall.

12. The implant unit according to claim 11, wherein the peripheral wall has upper and lower surfaces at least one of which may be textured.

13. The implant unit according to claim 12, wherein the at least one textured surface has ridges, serrations, or knurling to enhance engagement with the fractured surfaces of the bone and/or adjacent vertebral bodies.

14. The implant unit according to claim 12, wherein at least one of the upper and lower surfaces has a ledge defining portions of the at least one surface extending on different levels.

15. The implant unit according to claim 5, wherein the retaining portion includes a transverse member with a single wing extending in one lateral direction perpendicular to the insertion plane or with two wings extending in opposing lateral directions from the insertion plane defined by the implant portion.

16. The implant unit according to claim 15, wherein the transverse member has a stepwise inner surface facing the sidewall of the bone repair site.

17. The implant unit according to claim 6, wherein the retainer portion has at least one hole that has an oblong shape, traversed by the at least one fastner so as to allow controlled displacement of the bone implant relative to the at least one fastner to obtain a desired position of the implant unit before tightening the at least one fastner.

18. The implant unit according to claim 6, wherein the implant portion and the retaining portion are formed as a monolithic, one-piece body.

19. The implant unit according to claim 18, wherein the retaining portion has a peripheral surface provided with at least one threaded region to enable engagement of the retaining portion with the sidewall of the bone repair site, the implant portion may be provided with a respective thread to facilitate rotational insertion of the implant portion into the bone repair site.

20. The implant unit according to claim 6, wherein the retaining portion and the implant portion are detachably coupled to one another.

21. The implant unit according to claim 5, wherein the retaining portion and the implant portion are detachably connected to one another.

22. The implant unit according to claim 21, wherein the implant portion has a hole extending inwards from a proximal end of the implant portion and having a threaded surface, the retaining portion being provided with an opening and traversed by a screw after the opening and the hole have been aligned, the screw threadedly engages the threaded inner surface to prevent relative displacement between the implant and retaining portions.

23. The implant unit according to claim 22, wherein the implant portion has an outer threaded surface screwed into a central threaded opening formed in the retaining portion, mating with the threaded surface of the implant portion to prevent relative displacement between the implant and retaining portions.

24. The implant unit according to claim 22, wherein the implant portion has a flange extending laterally outwards from at least one end of the implant portion and is received in a stepped central opening in the retaining portion and dimensioned so that the flange extends flush with an outer surface of the retaining surface after being inserted into the diseased bone.

25. The implant unit according to claim 6, wherein the implant portions and the retaining portions are selectively demineralized to expose the collagen fibers to provide the selectively demineralized portions with the improved osteoinductive characteristics.

26. The implant unit according to claims 25, wherein the exposed collagen fibers are chemically cross-linked by a cross-linking agent selected from a group consisiting of formaldehyde, glutaraldehyde, acetaldehyde, glyoxal pyruvic aldehyde, dialdehyde starch, glycerol polyglycidyl ethers, polyethylene glycol diglycidyl ethers, polyvalent metallyic oxides, dicyclohexyl carbodiimide and/or a combination of these.

27. The implant unit according to claims 25, wherein the exposed collagen fibers are bound by reinforcing fibers.

28. The implant unit according to claim 6, wherein the implant portion and/or the retaining portion is formed from combinations of cancellous and cortical bone.

29. The implant unit according to claim 5, wherein the retaining portions have opposing ends spaced laterally outwards from the implant portion and each provided with a respective tab extending generally parallel to the implant portion.

30. The implant unit according to claim 5, wherein the retaining portion has at least two sections attached to one another by a flexible demineralized connecting portion and each of the at least two portions being integrally formed with a respective implant portion to provide a multilevel joining operation.

31. The implant unit according to claim 30, wherein the at least two sections, the flexible connecting portion and the implant portions form a monolithic, one-piece structure.

32. An implant unit for joining spaced vertebral bodies each having an inner face to be fused and a sidewall extending transversely to the inner face, wherein at least the sidewalls being recessed to have a niche, the implant unit comprising:

an implant portion extending in an insertion plane and into the intervertebral space and being interposed between the inner faces following discectomy; and

a retaining portion extending transversely to the insertion plane of the implant portion and shaped to engage the recessed sidewalls, the retaining portion being so dimensioned that upon insertion of the implant portion into the intervertebral space, the retaining portion is at least partially nested within the niche of the recessed sidewalls to bear loads imposed upon the spine.

33. The implant unit according to claim 32, wherein the implant portion has a thickness greater than the distance between the opposing inner faces defining the intervertebral space.

34. The implant unit according to claim 32, wherein the implant portion has a truncated conical portion narrowing in the posterior direction of the implant.

35. The implant unit according to claim 34, wherein the implant portion is provided with opposing top and bottom surfaces each formed with serrations, ridges, knurling and/or other surface roughening features.

36. The implant unit according to claim 35, wherein at least one of the top and bottom surfaces has a ledge defining a stepwise face extending complementary to the respective adjacent inner face of the surfaces to be fused.

37. The implant unit according to claim 32, wherein the retaining portion has an inner surface facing the sidewalls and having a ledge, whereas the ledge extends generally parallel to the insertion plane of the implant portion and is juxtaposed with an inner surface of the niche formed in the sidewalls of the adjoining vertebral bodies-to provide a greater contact area for the transmission of loads.

38. The implant unit according to claim 32, wherein the retaining portion has an outer peripheral surface extending substantially parallel to the insertion plane of the implant portion and supporting the surface which defines the niche provided in the sidewalls of the vertebral bodies.

39. The implant unit according to claim 32, further comprising a plurality of fasteners traversing respective openings formed in the retaining portions and penetrating the sidewall of the adjoining vertebral bodies.

40. The implant unit according to claim 39, wherein each of the openings is so dimensioned that the fasteners are capable of being multi-directionally displaced therein before being fixed to the sidewalls of the adjoining vertebral bodies to provide desired positioning of the implant portion.

41. The implant unit according to claim 32, wherein the implant and retaining portions form a monolithic, one-piece body made up of implantable material producing an osteogenic effect.

42. The implant unit according to claims 41, wherein the implantable material includes bone selected from a group consisting of bone particles, bone powder, bone chips, a bone composite including bone distributed in a polymeric binder, the bone composite further comprising biologically active components, medicinal agents, drugs or any combination thereof.

43. The implant unit according to claim 32, wherein the implant and retaining portions are detachably coupled.

44. A method of forming an implant unit comprising the steps of:

providing an implant portion made from implantable biocompatible material; and

providing a retaining portion made of osteogenic material and coupled to or integral with the implant portion so that the retaining and implant portions extend transversely to one another.

45. The method according to claim 44, further comprising the steps of carrying load across at least one vertebral segment, human or mammalian bone by inserting the implant portions in the intervertebral space between adjacent vertebral bodies, juxtaposing the retaining portion with the sidewalls of the adjacent vertebral bodies, and attaching the retaining portion to the sidewalls, so as to provide growth of new bone and fusion between the adjoining vertebral bodies, human or mammalian bone and the implant unit.

46. The method according to claim 45, wherein the adjacent vertebral bodies and the opposing sides of the implant portion juxtaposed with the vertebral bodies are recessed so as to have a plurality of multi-level surface portions of the vertebral bodies and the opposite sides of the implant portion extend complementary to one another and fusing during the period of fusion without relative motion therebetween.

47. The method according to claim 45, wherein the sidewalls of the adjacent vertebral bodies are recessed to form a niche receiving at least a part of the length of the retaining portion.

48. The method according to claim 47, further comprising the step of recessing the retaining portion so as to form different level portions thereof extending complementary to the recessed sidewalls thereby increasing a load-bearing surface of the retaining portion to accelerate fusion of the implant unit with the vertebral body while preventing backing of the implant portion away from the intervertebral space.

49. The method according to claim 46, further comprising the step of providing a plurality of fasteners extending through the retaining portion and adopted to penetrate the sidewalls.

50. The method according to claim 44, wherein the implant and retaining portions are made up from a unitary piece of the implantable osteogenic material to form a monolithic body or from separate pieces of the implantable osteogenic material, which is selected from the group consisting of mammalian bone tissue including bone particles, bone powder, or bone chips, and a bone composite comprising the bone tissue distributed in a polymeric binder and least one biologically active component, medicinal agents and drugs.