POSTERIOR PLATES IN THE MANAGEMENT OF CERVICAL INSTABILITY - LONG-TERM RESULTS IN 44 PATIENTS

Although posterior plates are increasingly used to manage cervical spinal instability, long-term follow-up evaluation of patients with a critical analysis of efficacy and complications has not been reported. The authors have retrospectively analyzed the outcome in 44 consecutive patients (37 males and seven females, age range 16 to 80 years) treated with posterior cervical plates. The indications for instrumentation were instability due to trauma in 42 cases, tumor in one, and infection in one. In four patients the follow-up period was limited to 3, 5, 11, and 16 months. Two patients died of chronic medical problems 4 and 9 months after treatment. The remaining 38 patients were followed from 2 to 6 years (mean 46 months). One motion segment was stabilized in 23 patients using two-hole plates; two motion segments were stabilized in the other 21 patients using three-hole plates. In the majority of patients (37 cases), supplemental bone grafting was not used. Patients were immobilized postoperatively in a Philadelphia collar. Solid arthrodesis was achieved in 39 (93%) of 42 patients. Three patients required revision of the cervical plating: in one patient with a C-5 burst fracture, two-hole plates were applied at C5-6 and progressive kyphosis mandated anterior fusion; the second patient required posterior wiring due to screw pull-out resulting from a technical error in screw insertion; the third patient, who refused to wear an orthosis postoperatively, also developed screw pull-out, In two patients who went on to spinal fusion, there was an increase in sagittal kyphosis (6 degrees and 8 degrees) without clinical sequelae. Screw loosening was noted in five patients, involving eight (3.8%) of the 210 lateral mass screws; this complication resulted in instrumentation failure or increased kyphosis in three cases. There were two superficial infections. This analysis indicates that posterior cervical plating is highly effective; at long-term follow-up review the cervical spine was successfully stabilized in 93% of cases. Plate failure was related to faulty screw placement, failure to include sufficient motion segments, and noncompliance with postoperative orthoses. Halo vest immobilization was unnecessary and supplemental bone grafting was generally not required for recent trauma.