Synthetic reinforced interbody fusion implants
View Patent ↗Interbody fusion implants that include a load bearing body composed of a calcium phosphate material hardened around one or more structural reinforcing members are provided. The reinforcing members aid the load bearing body in resisting bending forces and, in certain forms, aid in preventing expulsion of the implant after implantation. Methods for promoting fusion bone growth in the space between adjacent vertebrae and methods for making the inventive implants are also provided.
1. An interbody fusion implant, comprising:
a biocompatible load bearing body, said body comprised of a synthetic calcium phosphate material hardened around at least one structural reinforcing member for resisting bending forces when implanted, said body having a longitudinal axis and being sized and configured for engagement between two vertebrae and having a superior surface configured to contact one of said vertebrae, and an inferior surface configured to contact the other of said vertebrae, said structural reinforcing member being a straight cylinder disposed between said superior surface and said inferior surface and extending along a length of said body parallel to and offset from said longitudinal axis.
2. The interbody fusion implant of claim 1 , wherein said calcium phosphate ceramic is a calcium phosphate apatite.
3. The interbody fusion implant of claim 2 , wherein said calcium phosphate apatite is a low crystallinity apatite.
4. The interbody fusion implant of claim 1 , wherein said reinforcement member is comprised of a metal.
5. The interbody fusion implant of claim 4 , wherein said metal is a titanium mesh.
6. The interbody fusion implant of claim 4 , wherein said metal is selected from the group consisting of titanium, stainless steel, cobalt-chromium, tantalum, mixtures thereof and alloys thereof.
7. The interbody fusion implant of claim 1 , wherein said implant has a compressive strength of at least about 40 MPa.
8. The interbody fusion implant of claim 1 , wherein said body further comprises a tool engaging end defining a tool engaging hole for receiving a driving tool for implanting the spacer.
9. The interbody fusion implant of claim 1 , wherein said body has an outer surface that defines threaded bone-engaging portions.
10. The interbody fusion implant of claim 1 , wherein said implant is a dowel.
11. The interbody fusion implant of claim 1 , wherein said implant is a wedge.
12. The interbody fusion implant of claim 1 , wherein said body further includes a wall connecting said superior surface and said inferior surface.
13. The interbody fusion implant of claim 12 , wherein said body is elliptical.
14. The interbody fusion implant of claim 1 , wherein said body further defines at least one thru-hole, and said structural reinforcing member is parallel to and offset from said thru-hole.
15. The interbody fusion implant of claim 14 , wherein said body has a longitudinal axis and said thru-hole extends perpendicular to said longitudinal axis.
16. The interbody fusion implant of claim 15 , wherein said body further includes an osteogenic material disposed within said thru-hole.
17. The interbody fusion implant of claim 16 , wherein said osteogenic material comprises natural bone, demineralized bone, a calcium phosphate material, a bioceramic, bioglass, an osteoinductive factor and mixtures thereof.
18. The interbody fusion implant of claim 17 , wherein said osteoinductive factor comprises a bone morphogenetic protein.
19. The interbody fusion implant of claim 18 , wherein said bone morphogenetic protein comprises a recombinant protein.
20. The interbody fusion implant of claim 19 , wherein said recombinant bone morphogenetic protein comprises a human protein.
21. The interbody fusion implant of claim 20 , wherein said recombinant human protein comprises BMP-2, BMP-4, BMP-7, or heterodimers thereof.
22. The interbody fusion implant of claim 1 , wherein said reinforcing member extends parallel to said superior and inferior surfaces.
23. The interbody fusion implant of claim 1 , wherein said reinforcing member further includes a second straight cylindrical member that is offset from and not intersecting said longitudinal axis, with said longitudinal axis lying between said straight cylindrical members.
24. An interbody fusion implant, comprising:
a load bearing body formed of a hardened synthetic calcium phosphate material and having a longitudinal axis, said body including at least one internal reinforcing member adapted to resist bending or tensile forces along a length of said body, said body sized and configured for engagement between two vertebrae and having a first surface for contacting a first of said vertebrae and a second surface for contacting another of said vertebrae, said body further having a hole extending between a first opening in said first surface and a second opening in said second surface and an axis parallel to the longitudinal axis of the body, said reinforcing member comprising at least one straight cylinder, said cylinder being offset from said hole and non-perpendicular to said hole axis.
25. An interbody fusion implant, comprising:
a cylindrical biocompatible load-bearing body, said body comprised of a synthetic calcium phosphate material hardened around first and second straight cylindrical structural reinforcing members for resisting bending forces when implanted, said body having a longitudinal axis and being sized and configured for engagement between two vertebrae and having a superior surface configured to contact one of said vertebrae, and an inferior surface configured to contact the other of said vertebrae, said structural reinforcing member being disposed between said superior surface and said inferior surface so that said structural reinforcing members are parallel or oblique with respect to said longitudinal axis and to each other, said structural reinforcing members being offset from said axis and separated from each other so that neither structural reinforcing member intersects said axis.
26. The apparatus of claim 25 , wherein said body includes an opening extending through said superior surface and said inferior surface and along said longitudinal axis, with said structural reinforcing members being offset to the outside of said opening.
27. The apparatus of claim 25 , wherein said structural reinforcing members are placed with respect to said longitudinal axis so that a perpendicular line can be drawn from said first structural reinforcing member to said second structural reinforcing member that intersects said longitudinal axis.