Accuracy of Axis Drill Guides in the Cases of Atlantoaxial Instabilities Associated With High-Riding Vertebral Arteries, Narrow Pedicles, and Complex Deformities: Comparison of 3 Fixation Methods

Abstract

The current study's objective was to contrast the accuracy of C2 navigation template-assisted versus free-hand pedicle and/or pars screw fixation in high-risk cases where a high-riding vertebral artery or narrow pedicle and complex deformities were associated. In our hospital, CT data of 30 subjects with pathology on C0-1-2, who had risk factors for VA injury, that were complex cervical deformities, atlantoaxial instabilities with narrow C2 pedicle and/or HRVA variations were retrospectively reviewed. Using CAD software and desktop printer we printed three sets of high cervical models per case. We divided them into three groups using three different C2 screw fixation techniques: the free hand pars screw fixation group, the free hand pedicle screw fixation group, and the navigation template-assisted pedicle screw fixation group. After 180 screw placements were finished, the parts underwent a CT scan. Then the breach rates on postoperative scans were measured. Our results stated that the accurate placement rate is not noticeably different between navigation template-assisted and free hand pedicle screws, where the HRVA and narrow pedicles associated, but was better in navigational template group with complex deformities. Pars screws were found to be superior in terms of accuracy. The current study suggests that navigational template assisted pedicle screws are risky for high-risk individuals with abnormal anatomy, such as those with a high-riding vertebral artery, a narrow pedicle, and complex abnormalities, and alternative C2 pars screws may be a reliable option for such individuals.