TRANSPEDICULAR INSTRUMENTATION AND SHORT-SEGMENT FUSION OF THORACOLUMBAR FRACTURES - A PROSPECTIVE-STUDY USING A SINGLE INSTRUMENTATION SYSTEM

Eleven patients were prospectively treated with bilateral short-segmen t transpedicular instrumentation using the Posterior Segment Fixator ( Ace Medical Co., Los Angeles, CA, U.S.A.) construct combined with post erolateral fusion using autogenous iliac crest bone graft for the trea tment of thoracolumbar vertebral fractures. All patients were evaluate d clinically, radiographically, and functionally for a minimum of 2 ye ars (mean 33 months). Four of the 11 patients (36.3%) had breakage or disengagement of the caudad screws during this interval. During the fo llow-up period, the angle of kyphosis increased an average of 12.9 deg rees. The loss of correction was greater in those patients in whom the instrumentation failed (22 degrees) than in those patients in whom it did not (7.7 degrees). Five of the patients (45.5%) had a progressive increase in the angle of kyphosis of 10 degrees or more. At follow-up , the average loss of anterior vertebral body height for all 11 patien ts was 14% when compared with the body height that had been attained a t surgery. Six of these patients (54.5%) had 10% or more loss of anter ior body height. Despite the high incidence of failure of the instrume ntation, progressive increase in the angle of kyphosis, and progressiv e loss of anterior vertebral body height, there was no worsening in th e patients' Frankel grade postoperatively. The high rate of hardware f ailure and major postoperative loss of fracture reduction associated w ith this construct suggest that posterior short-segment pedicle-screw instrumentation with the Posterior Segment Fixator was not adequate to ensure stabilization of thoracolumbar fractures in this small group o f patients. Maintenance of post operative fracture reduction was the m ost consistent predictor of satisfactory functional outcome.