Stabilization of atlantoaxial instability.

Eight patients with atlantoaxial instability were treated by arthrodesis of the first and second cervical spine. Internal fixation was achieved by passing two 18 gauge stainless steel wires beneath the posterior arch of the atlas and around a threaded Steinmann pin which was drilled through the base of the spinous process of the axis. The wires were tightened over a preshaped iliac bone graft. A solid fusion was achieved in all patients. The risk of compression of the cord is decreased with this technique because the wires are not passed under the lamina of the axis. The lateral placement of the wires provides an excellent internal fixation and control of the forward flexion and rotation.