Intervertebral body fusion cage with keels and implantation methods

1. An intervertebral spinal fusion implant comprising:

a D-shaped body including a peripheral wall that encloses an inner cavity, said peripheral wall having a D-shaped cross-section and including a curved anterior end and an opposite posterior end with an anterior-posterior axis drawn from said curved anterior end to said posterior end, said body having superior and inferior sides with said superior side adapted to engage an upper vertebral body and said inferior side adapted to engage a lower vertebral body, said superior and inferior sides each including an opening communicating with said inner cavity, said peripheral wall defining apertures located on opposite sides of the peripheral wall substantially parallel to said anterior-posterior axis, said apertures communicating with said inner cavity to place said inner cavity in communication with an exterior of said body;

a rib extending across said inner cavity and including a first end joined to said peripheral wall adjacent said curved anterior end and a second end joined to said peripheral wall adjacent said posterior end; and

a first keel extending from said rib in a superior direction, a second keel extending from said rib in an inferior direction, and wherein each of said keels extends along a longitudinal axis substantially parallel to said anterior-posterior axis and at least one of said keels has a maximum width that is greater than a minimum width of said rib.

2. The implant of claim 1 wherein said peripheral wall further includes opposite sides extending generally parallel with one another along said anterior-posterior axis from said curved anterior end to said posterior end.

3. The implant of claim 2 wherein said opposite sides are planar.

4. The implant of claim 1 wherein each of said keels has a T-shaped cross section.

5. The implant of claim 1 wherein each of said keels extends from an exterior of said peripheral wall at said curved anterior end to an exterior of said peripheral wall at said posterior end.

6. The implant of claim 1 wherein each of said keels extends along an entire outer dimension of said body along said anterior-posterior axis.

7. The implant of claim 1 wherein said keels are formed integral with said rib to define a single, unitary piece of said body.

8. The implant of claim 1 wherein said superior and inferior sides taper relative to one another to provide said body with a wedge shape.

9. The implant of claim 8 wherein said superior and inferior sides taper relative to one another along said anterior-posterior axis to provide said body with said wedge shape.

10. The implant of claim 9 wherein said superior and inferior sides taper along an entire dimension of said body from said curved anterior end to said posterior end.

11. The implant of claim 8 wherein said superior and inferior sides taper relative to one another in a direction generally perpendicular to said anterior-posterior axis to provide said body with said wedge shape.

12. The implant of claim 8 wherein said superior and inferior sides are substantially planar.

13. The implant of claim 8 wherein said body tapers from a narrower end at one of said anterior and posterior ends to a broader end at the other of said anterior and posterior ends.

14. The implant of claim 13 wherein said body is narrower at said anterior end and broader at said posterior end.

15. The implant of claim 1 wherein said superior and inferior sides each define a plurality of teeth.

16. The implant of claim 1 wherein at least one of said apertures is positioned on each side of said first and second keels.

17. The implant of claim 1 further comprising a bone growth promoting material positioned within said inner cavity, said bone growth promoting material selected from the group of materials consisting of naturally occurring bone, processed bone, synthetic bone, hydroxyapatite, calcium phosphate compounds, naturally occurring bone morphogenic proteins, recombinant bone morphogenic proteins, synthetic bone morphogenic proteins, growth factors, and cytokines.

18. The implant of claim 1 wherein said body is formed of a material selected from the group consisting of bioceramics, calcium phosphate ceramics, chrome cobalt, titanium, stainless steel, biocompatible carbon fiber reinforced polymer, biocompatible polymers, copolymers, and blends and composites of polymers.

19. The implant of claim 18 wherein said body is comprised of a biocompatible polymer including polyaryl ester ketone.

20. The implant of claim 1 wherein said keels are formed integral with said rib.

21. An intervertebral spinal fusion implant comprising:

a D-shaped body including a peripheral wall that encloses an inner cavity, said peripheral wall having a D-shaped cross-section and including a curved anterior end and an opposite posterior end with an anterior-posterior axis drawn from said curved anterior end to said posterior end, said body having superior and inferior sides with said superior side adapted to engage an upper vertebral body and said inferior side adapted to engage a lower vertebral body, said superior and inferior sides each including an opening communicating with said inner cavity, said peripheral wall defining apertures located on opposite sides of the peripheral wall substantially parallel to said anterior-posterior axis, said apertures communicating with said inner cavity to place said inner cavity in communication with an exterior of said body;

a rib extending across said inner cavity and including a first end joined to said peripheral wall adjacent said curved anterior end and a second end joined to said peripheral wall adjacent said posterior end; and

a first keel extending from said rib in a superior direction, a second keel extending from said rib in an inferior direction, and wherein each of said keels has a T-shaped cross section extending along a longitudinal axis substantially parallel to said anterior-posterior axis such that at least one of said keels has a maximum width that is greater than a minimum width of said rib, and wherein said keels are formed integral with said rib.

22. The implant of claim 21 wherein said peripheral wall further includes opposite planar sides extending generally parallel with one another along said anterior-posterior axis from said curved anterior end to said posterior end.

23. The implant of claim 21 wherein each of said keels extends along an entire outer dimension of said body along said anterior-posterior axis from an exterior of said peripheral wall at said curved anterior end to an exterior of said peripheral wall at said posterior end.

24. The implant of claim 21 wherein said superior and inferior sides taper relative to one another to provide said body with a wedge shape.

25. The implant of claim 24 wherein said superior and inferior sides taper relative to one another along said anterior-posterior axis to provide said body with said wedge shape.