COMPLICATIONS OF THE WILTSE PEDICLE SCREW FIXATION SYSTEM

The purpose of the current study is to retrospectively review the incidence and types of complications occurring using a single pedicle screw fixation system for lumbar spine fusions. For a 3-year period beginning in July 1987, 470 patients underwent spinal fusion and instrumentation with the Wiltse Pedicle Screw Fixation System. Although multiple configurations of the Wiltse System were included, the predominant construct was that of segmental pedicle screw fixation. Complications occurred in a total of 29 patients, for an overall complication rate of 6%. Among the complications were 10 wound problems (2%) that included 2 seromas requiring drainage and 3 superficial wound infections. The remaining five wound complications were deep wound infections requiring irrigation and debridement. The overall deep wound infection rate was 1%. Neurologic complications occurred in two patients, one with temporary foot drop and one with persistent L5 nerve root irritation confirmed by electromyogram (EMG). Both of these patients underwent anatomic workup, which failed to reveal any evidence of impingement by either screw or other hard tissue. Two intraoperative complications occurred, both involving fracture of the L5 pedicle. No adverse sequela resulted. There were 15 hardware complications, for an overall rate of 3%. This included four patients with broken screws (a total of eight screws). There were three failures at the screw-bone interface, as well as four patients with uncoupling of the screw rod linkage. In addition, there were four broken rods encountered. A total of 122 Wiltse devices were removed, for an overall removal rate of 25%. These were removed at an average of 10.5 months postoperatively, with a range of 7 weeks to 34 months. All fusions were explored at the time of hardware removal, and 111 of 122 fusions were judged successful in terms of achieving the goal of arthrodesis. The overall fusion rate was 91%. Based on the results of this study, it is thought that this method is both safe and efficacious when used appropriately.