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 associ ated Complications in 21 consecutive patients treated with a plate and screw fixation system applied to the lateral masses of the cervical s pine. Objectives. To determine the clinical safety of lateral mass scr ews by determining their anatomic location and clinical complications in a consecutive patient series. Summary of Background Data. Lateral m ass plating has been advocated for procedures in which wiring techniqu es cannot be used, especially in instances in which the posterior elem ents are deficient. Methods. The first 21 consecutive patients who und erwent posterior cervical arthrodesis and lateral mass plating with a single fixation system were reviewed prospectively. Computed tomograph y scans taken after surgery were reviewed independently by an orthoped ic spinal: surgeon and by a radiologist to evaluate screw tip position . Clinical and radiographic outcome was assessed at each visit after s urgery, Results. Ten of 164 (6.1%) lateral mass screws were malpositio ned in six patients. Three symptomatic patients underwent four additio nal operative procedures to remove or replace the malpositioned screws . All patients had radiographic union, and no patient developed mechan ical implant failure requiring removal of instrumentation. Radiographi c evaluation noted that 17% of the screws were in the central axial zo ne of the lateral mass on computed tomography. Conclusions. Lateral ma ss plating was associated with no vertebral artery or spinal cord inju ry, There was a 1.8%-per-screw risk of radiculopathy, which correspond s with published cadaveric studies. Radicular symptoms improved with s crew removal in each case. The advantages of segmental fixation achiev ed with lateral mass plates and screws must be weighed against the ris k of radiculopathy.