ATLANTOAXIAL STABILIZATION WITH POSTERIOR TRANSARTICULAR SCREW FIXATION - TECHNICAL DESCRIPTION AND REPORT OF 22 CASES

MAGERL'S TECHNIQUE OF combining C1-C2 posterior screw fixation with a supplemental bone-wire fusion has been advocated for the management of atlanto-axial instability. Between October 1990 and August 1992, a modification of this technique was used in the treatment of 22 patients with this disorder. In the absence of spinal deformity or neoplastic disease, screw fixation and bony fusion were used alone without associated wiring, thus avoiding the risk of neural injury resulting from the sublaminar passage of wire and the retrodisplacement of ventral structures. Patient ages ranged from 30 months to 80 years; follow-up ranged from 5 to 27 months, with a mean of 14.9 months. The causes of the instabilities were as follows: eight cases of nonunion of Type II odontoid fracture, four cases of rheumatoid arthritis, three cases of tumor, two cases of ligamentous instability, two cases of pseudoarthrosis after bone-wire fusion, two cases of halo noncompliance, and one case of Os odontoideum. All 20 patients who underwent fusion were placed in a Philadelphia collar for 12 weeks. Nineteen of 20 (95%) patients achieved solid fusion. Twenty-one of 22 (95%) had significant reduction in preoperative pain. No patient developed myelopathy or bulbar findings. The one intraoperative complication was an inability to achieve secure screw purchase on one side that required unilateral screw placement with a Gallie fusion-using cable. Postoperative complications included one patient with a superficial wound infection that resolved after local debridement and antibiotics and suboccipital numbness in two patients. Progression of spinal deformity, screw pullout or breakage, and neurological or vascular complications did not occur. This limited experience demonstrates that posterior transarticular screw fixation is an important option in the management of patients with atlanto-axial instability. Fusion rates thus far appear to be comparable or superior to standard wiring techniques, and the need for postoperative bracing and the potential for complications have been reduced.