Posterior stabilization of the lower cervical spine with lateral mass plates and screws

Posterior cervical fixation using lateral mass plates and screws is becoming increasingly used and accepted.Advantages include increased rigidity, ability to be used in cases where the lamina or spinous processes are deficient or missing, use across the occipito-cervical or cervico-thoracic junction, and need for less postoperative bracing. Safe placement of lateral mass screws requires complete exposure and identification of the boundaries of the lateral masses. The starting point for screw placement is 1 to 2 mm medial to the center of lateral mass. The screws are angulated outward 10 to 20 degrees and cranially 20 to 30 degrees to be parallel to the facet joints. An adjustable drill guide facilitates safe drilling and tapping techniques. All 102 patients with unstable cervical spines treated with AO reconstruction plates and autogenous bone graft had healed fusions based on flexion-extension radiographs. The reductions achieved postoperatively were maintained at follow-up. Two patients had transient radiculopathies secondary to screw placement. The indications for lateral mass fixation include cases where the lamina or spinal processes are deficient or missing, multilevel or rotational instabilities, when extension to the thoracic spine or occiput is required or when decreased bracing is beneficial.