Rigid internal fixation with lateral mass plates in multilevel anterior and posterior reconstruction of the cervical spine.

STUDY DESIGN: A retrospective clinical and radiographic analysis was performed on 17 patients with multilevel cervical disease who were treated with anterior and posterior reconstruction with a new rigid, segmental, internal fixation system applied to the lateral masses. OBJECTIVES: To determine the applicability, safety, and clinical efficacy of an instrumentation system used as a cervical lateral mass plate in the management of complex spinal disorders. SUMMARY OF BACKGROUND DATA: Cervical disorders involving three or more levels present a difficult reconstruction problem, especially if the posterior elements are deficient. Segmental fixation with lateral mass plating provides an alternative method to situations that would otherwise require a halo. METHODS: Seventeen patients treated by a single surgeon underwent cervical reconstruction surgery involving three or more levels. All patients had anterior decompression and reconstruction and a posterior fusion with rigid internal fixation with a device applied to the lateral masses of the cervical vertebrae. Patients were reviewed clinically and radiographically to determine the efficacy and safety of this method of fixation. RESULTS: Of the 15 patients with adequate follow-up data that were studied, the condition of 13 patients, (87%) was improved, that of one patient (6.7%) was the same, and that of another (6.7%) was worse after surgical intervention. Sagittal alignment was restored to within 5 degrees of the preoperative lordosis in active extension by the modified Cobb method and the Gore method. No patient had radiographic nonunion. One patient had a sensory radiculopathy associated with an overpenetrated lateral mass screw that partially resolved after hardware removal. One patient had asymptomatic loosening of a C7 lateral mass screw. CONCLUSIONS: Segmental posterior fixation with lateral mass plating provides more rigid immobilization than traditional techniques, allows restoration and maintenance of spinal alignment, obviates the need for halo immobilization, and is associated with a low incidence of neurovascular injury.

Posterior cervical arthrodesis and stabilization with a lateral mass plate. Clinical and computed tomographic evaluation of lateral mass screw placement and associated complications.

STUDY DESIGN: A prospective study evaluating screw position and associated complications in 21 consecutive patients treated with a plate and screw fixation system applied to the lateral masses of the cervical spine. OBJECTIVES: To determine the clinical safety of lateral mass screws by determining their anatomic location and clinical complications in a consecutive patient series. SUMMARY OF BACKGROUND DATA: Lateral mass plating has been advocated for procedures in which wiring techniques cannot be used, especially in instances in which the posterior elements are deficient. METHODS: The first 21 consecutive patients who underwent posterior cervical arthrodesis and lateral mass plating with a single fixation system were reviewed prospectively. Computed tomography scans taken after surgery were reviewed independently by an orthopedic spinal surgeon and by a radiologist to evaluate screw tip position. Clinical and radiographic outcome was assessed at each visit after surgery. RESULTS: Ten of 164 (6.1%) lateral mass screws were malpositioned in six patients. Three symptomatic patients underwent four additional operative procedures to remove or replace the malpositioned screws. All patients had radiographic union, and no patient developed mechanical implant failure requiring removal of instrumentation. Radiographic evaluation noted that 17% of the screws were in the central axial zone of the lateral mass on computed tomography. CONCLUSIONS: Lateral mass plating was associated with no vertebral artery or spinal cord injury. There was a 1.8%-per-screw risk of radiculopathy, which corresponds with published cadaveric studies. Radicular symptoms improved with screw removal in each case. The advantages of segmental fixation achieved with lateral mass plates and screws must be weighed against the risk of radiculopathy.