Onlay technique for occipitocervical fusion.

Twenty-eight occipitocervical fusions using the onlay technique were performed in 27 patients ranging in age from 13 to 77 years (average age, 47.6 years). The indications for fusion included neurologic involvement from atlantoaxial instability associated with superior migration of the odontoid and destructive changes at the occiput-C1-C2 articulation, causing pain unrelieved by conservative treatment. Preoperative diagnoses included rheumatoid arthritis, congenital anomalies, posttraumatic, failed C1-C2 fusions, ankylosing spondylitis, and tumor. A standard posterior exposure of occiput-C1-C2 was used, and iliac crest bone graft was placed over the area to be fused. Postoperative immobilization consisted of skull tong traction, minerva jacket, and halo apparatus. There were no neurologic complications, two superficial wound infections, and minor difficulties with halo loosening. There was one perioperative death. Primary fusion was obtained in 89% of patients at an average of 12.8 weeks. Occipitocervical fusion by the onlay technique is safe, requires no internal fixation, and has a high success rate when compared with other methods of obtaining fusion in the occipitocervical region.