A free-hand technique for pedicle screw placement in the lower cervical spine

To describe a free-hand method for pedicle screw placement in the lower cervical spine with no intraoperative imaging monitors, and to evaluate the safety of this technique.

A study of the free-hand technique of cervical pedicle screw placement was conducted by postoperative radiological review and follow-up. Thirty-six patients who had had cervical reconstruction with posterior plate utilizing pedicle screw fixation, and been followed for a minimum of 2 years, were studied. The position of the pedicle screw was evaluated by postoperative oblique radiographs and axial computed tomograms. Clinical outcomes were measured by Odem's criteria.

A total of 144 screws of diameter 3.5 or 4.0 mm were inserted into the cervical pedicles in 36 patients. Postoperative images showed that 16 (11.1%) of the screws had penetrated the pedicle walls. Among them, 10 (6.9%) screws had penetrated the lateral, 4 (2.8%) the superior and 2 (1.3%) the inferior walls. However, there were no neurological or vascular complications related to the malpositioned screws during a minimum of 2 years follow-up. In addition, Odem's scores were applied postoperatively in all patients except one with complete neurological deficit.

Based on 144 screw placements, cervical pedicle screw insertion utilizing a free-hand technique without intraoperative imaging guidance seems to be safe and reliable. However, solid knowledge of the anatomy of the cervical pedicle and adjacent neurovascular bundles, and careful preoperative review of cervical images, are imperative for successful screw placement in the cervical spine.