Abstract
PURPOSE: The purpose of this study was to describe a free-hand pedicle screw insertion technique and to evaluate the accuracy of pedicle screw placement and validity of pedicle screw fixation in patients with subaxial cervical spine injuries. METHODS: We retrospectively reviewed 32 consecutive patients with subaxial cervical spine injuries who underwent posterior cervical fixation using our cervical pedicle screw (CPS) insertion technique. We also assessed the clinical and radiological outcomes and the accuracy of pedicle screw placement. RESULTS: The mean preoperative kyphosis was 4.0°, which was corrected to -5.2° after the operation, and the mean kyphosis angle was -4.4° at the final follow-up. The mean preoperative disc height ratio was 81.9%, and it improved to 105.4% after the operation, which was maintained until the final follow-up measurement of 103.4%. Bony union was achieved, and there were no instrumentation failures in any patient. Overall, 127 pedicle screws were inserted, of which 112 (88.1%) were classified as grade 1 (exact intrapedicular screw positioning), 10 (7.8%) as grade 2 (perforation <50% of the screw diameter), and 5 (3.9%) as grade 3 (perforation more than 50% of the screw diameter). CONCLUSION: In our technique, a gutter is created using a high-speed burr at the transitional area between the lateral mass and lamina similar to the procedure in double-door laminoplasty to identify an entry point for CPS insertion. It is easy for general spine surgeons to identify a CPS insertion entry point using our technique.