Spinal implant having deployable bone engaging projections
Instrumentation is disclosed for inserting an interbody spinal fusion implant for implantation at least in part within and across the generally restored height of a disc space between two adjacent vertebral bodies of a human spine. The implant has an external housing and a substantially hollow internal rotatable member having bone engaging projections that are deployable through the housing to penetrably engage the adjacent vertebral bodies.
1. An interbody spinal implant comprising:
a body having an upper portion and a lower portion, said upper portion having a first arcuate portion, a second arcuate portion, and a non-arcuate portion separating said first and second arcuate portions, each of said arcuate portions including a plurality of recesses;
first and second rotatable shafts positioned at least in part within said first and second arcuate portions, respectively, each of said first and second rotatable shafts having an axis of rotation, each of said rotatable shafts including a plurality of spaced-apart bone engaging projections, said first and second rotatable shafts each being rotatable from an undeployed position wherein said bone engaging projections are positioned at least in part within said body of the implant to a deployed position wherein said bone engaging projections are positioned at least in part outside of said body of the implant, said bone engaging projections extending through respective ones of said recesses and into bone when in the deployed position; and
a vertical plane bisecting said implant and passing through said non-arcuate portion of said upper portion, wherein said first and second arcuate portions are located on opposite sides of the vertical plane.
2. The spinal implant of claim 1 , wherein the axes of said first and second rotatable shafts are parallel to one another in a single horizontal plane.
3. The spinal implant of claim 1 , wherein said body has a height from said lower portion to said upper portion, and a width transverse to the height, the width of said body being greater than the height of said body.
4. The spinal implant of claim 1 , wherein said lower portion of said body is symmetrical to said upper portion of said body relative to a horizontal plane bisecting said implant.
5. The spinal implant of claim 1 , wherein each of said rotatable shafts has a maximum diameter greater than a minimum height of said implant.
6. The spinal implant of claim 1 , wherein each of said rotatable shafts has a length, said plurality of bone engaging projections being spaced along a majority of the length of each rotatable shaft.
7. The spinal implant of claim 1 , wherein said bone engaging projections have a uniform shape.
8. The spinal implant of claim 1 , wherein said implant is a spinal fusion implant.
9. The spinal implant of claim 1 , wherein said implant includes a hollow interior, said recesses being in communication with said hollow interior.
10. The spinal implant of claim 1 , in combination with hydroxyapatite.
11. The spinal implant of claim 1 , wherein said lower portion has a third arcuate portion, and a fourth arcuate portion, and a non-arcuate portion separating said third and fourth arcuate portions, wherein the vertical plane passes through said non-arcuate portion of said lower portion, said third and fourth arcuate portions being on opposite sides of the vertical plane.
12. The spinal implant of claim 1 , wherein said plurality of recesses are adapted such that said bone engaging projections are rotated to said deployed position when said first and second rotatable shafts rotate in a first direction, and said bone engaging portions are rotated to said undeployed position when said first and second rotatable shafts rotate in a second direction opposite said first direction.
13. The spinal implant of claim 1 , wherein at least one of said first and second rotatable shafts further comprise at least one opening adapted to permit bone growth through said at least one of said first and second rotatable shafts.