Anterior cervical fusion using a modified tricortical bone graft: a radiographic analysis of outcome

A technique was developed to resist graft extrusion by means of mechanical interlocking between graft and vertebrae. A 4-mm burr is used to create a transverse trough (mortise) across the posterior aspect of each endplate. A reversed tricortical graft is shaped to have a ridge (tenon) composed of cortical bone on the upper and lower surfaces of its posterior portion. The ridges lock into the troughs to form a double mortise and tenon joint. Of 117 discs (102 patients) treated, adequate radiographs were available of 106 discs (in 92 patients) of which 89% were fused at last follow-up. Radiographic analysis showed significant (p < 0.001) increases in disc height and extension immediately postoperatively and a return to the preoperative values by the time of fusion. This technique completely eliminated graft extrusion without any reduction in fusion rate compared with most other reported results with the standard tricortical technique.