Method and apparatus for spinal facet joint fusion using irregularly shaped cortical bone implants
A method and apparatus for spinal fusion at the facet joint using an irregularly shaped implant where the orientation of the implant can be preselected before implantation.
1. A method of mounting an implant in a facet joint C1-C2 and L5-S1, the method comprising the steps of:
(a) cutting an arthroscopic type portal in the tissue of a patient outside a diseased or damaged facet joint;
(b) using a positioning selection tool to select an orientation of a plug to be implanted, the selected orientation including a plurality of prongs defining an orientation of the plug to be implanted;
(c) placing an implantation guide in operative connection with the positioning selection tool;
(d) while maintaining at least two distinct prongs of the selected orientation removing the positioning selection tool from operative connection with the implantation guide;
(e) placing a cutting tool in operative connection with the implantation guide, and using operative connection between the cutting tool and implantation guide to form a shaped hole between two opposed bones forming the facet joint, the shaped hole having at least the two distinct prongs of orientation specified in step “d”; and
(f) inserting a preshaped plug into the hole, the plug having a shape substantially the same as the hole.
2. The method of claim 1 , wherein in step “f” the plug comprises:
(i) a substantially solid body having a longitudinal axis;
(ii) a plurality of opposed arms, the arms being symmetrically disposed around the longitudinal axis; and
(iii) the body being formed from a material selected from the group consisting of synthetic cortical bone, a harvested synthetic cortical and compacted iliac crest graft and a cadaveric allograft.
3. The method of claim 2 , wherein there are four arms.
4. The method of claim 3 , wherein the four arms form an “X”.
5. The method of claim 2 , wherein the arms include tips which are rounded.
6. The method of claim 5 , wherein between each pair of arms is a valley which valley is rounded.
7. The method of claim 2 wherein the body is formed from synthetic cortical bone.
8. The method of claim 2 wherein the body is formed from a harvested and compacted iliac crest graft.
9. The method of claim 2 wherein the body is formed from a cadaveric allograft.