Analysis of factors related to perforation of lateral wall by lower cervical vertebral pedicle screw

Abstract

Objective To analyze the risk factors related to perforation of lateral wall by lower cervical pedicle screw instrumentation in the treatment of cervical spinal disorders. Methods A retrospective review was made to analyze 214 cervical vertebral injury patients ( 1 024 pedicle screws were used) treated with pedicle screw instrumentation at C3-7 from July 2004 to July 2009. Lateral walls of 18 patients were perforated (a total of 28 pedicle screws). The surgeons assessed the position and the angle of the screw in the pedicle, and the relation and the distance between the screw and the pedicle walls by carefully probing intraoperative walls of cervical pedicles and studying postoperative thin-slice computed tomography (CT) scan of the fixed vertebral segments of the cervical spine. The data of patients with lateral wall perforation was recorded and analyzed statistically. Results Perforation of the lateral wall occurred in 18 patients (28 pedicle screws). Backward step by step Logistic regression analysis was used and two variables were selected in the end. Conclusions Ratio variance between inner and lateral wall is the risk factor of perforation in the lateral wall associated with lower cervical pedicle screw instrumentation, while the angle variance between implanted screws and CT measurements is the protection factor of perforation in the lateral wall. Key words: Spinal fractures ; Cervical vertebrae; Pedicle; Risk factors