Radiological evaluation of C1 pedicle screw anatomic feasibility.

C1 pedicle screw instrumentation is a recently documented technique, which may have benefits over other more popularised procedures, however it may not be possible in all patients. This study aims to investigate the applicability of the C1 pedicle screw technique to a cohort of patients through assessment of radiological parameters. A retrospective review of 150 consecutive patients undergoing computer tomography (CT) of the cervical spine was performed. Based on defined parameters images were assessed for feasibility of placement of pedicle screws. C1 pedicle height (PH), pedicle width (PW), screw trajectory length (LML) and width (LMW) were recorded with PH  ≥ 4 mm defined as the primary outcome measure. A total of 115 patients and 230 C1 pedicles were examined. The mean PH was found to be 5.1 mm. 207 pedicles were deemed suitable for placement of pedicle screw instrumentation. Overall C1 pedicle screw instrumentation was deemed possible in 94.6% of male pedicles and 84% of female pedicles. C1 pedicle screw instrumentation is feasible to be performed in more than 90% of the patients. Crown