Anterior spinal fusion: experimental evaluation of technique

Anterior spinal fusion was carried out in 29 adult mongrel dogs in order to evaluate: (a) the degree to which intervertebral discs and endplates should be removed; (b) the optimum source of bone graft material and the best technique for implantation; (c) the effect of a previous posterior spinal fusion on the outcome of anterior spinal surgery; and (d) possible deleterious effects on the spinal canal. A total of 54 disc spaces were fused. In those fusions where none of the disc was resected, a 38% rate of successful fusion was achieved; this compares with 70% when one-half of the disc and endplates was removed and 67% when the entire disc and endplates were removed. The best fusions resulted when cancellous bone was packed tightly into disc spaces. Strut grafts were not successful. Posterior spinal fusions provided good stability for subsequent anterior fusions. Anterior spinal fusion carries a significant risk of spinal stenosis, either through osteophyte formation caused by surgical trauma or through hypertrophy of the bone related to the healing process.