To introduce a new classification method and analyze related risk factor about lateral wall perforation associated with lower cervical pedicle screw and free-hand insertion technique. A Retrospective study was made to analyze 214 patients (1024 screws) with various cervical spine disorders, involved in pedicle screw instrumentation at C3-7 from July 2004 to July 2009. Researchers assessed the position of the screws in the pedicle by carefully probing intraoperatively and studying postoperative thin-slice computed tomography scan. Perforation of lateral wall was classified into two phases. Phase I refers to the burst of the pedicle by screw, which means that the length of screw threads penetrating the external cortex of pedicles on CT scan is 2 mm, whereas in Phase, the length is >2 mm. The Penetrated screws and related factors were analyzed though Backward Stepwise (Wald) Logistic regression.Introduction
Methods
