Research into the anatomy of the subaxial cervical pedicle for ensuring screw insertion safety

Abstract

The study aimed to determine the optimal entry points and trajectories for posterior subaxial cervical pedicle screw (CPS) fixation. Computed tomography (CT) and Mimics software were used to evaluate the subaxial cervical pedicle in 42 cervical spine CT scans. The width of the cervical pedicle was measured and compared at medial angulations of 30°, 35°, 40°, 45°, 50°, 55°, and 60° relative to the midline sagittal plane. Based on an observational examination of the positions of all cervical 3-dimensional models and screws, the proposed entry point for C3–7 CPS was analyzed. Although the variations in C3–6 pedicle width (PW) among 45°, 50°, and 55° were not statistically significant, they were significantly larger than the differences among 30°, 35°, 40°, and 60° angles (P < .05). The differences in C7 PW between the 30°, 35°, 40°, and 45° angles were not statistically different even though the 30°, 35°, 40°, and 45° angles were significantly bigger. (P < .05). The proposed entry point for C3–7 CPS was below the junction of the lateral and lower borders of the superior articular process joint surface. The entry point for C3–7 levels was below the junction of the lateral and lower borders of the superior articular process joint surface. The optimal medial angulation for the posterior C3–6 CPS was 45°–55° and that for the posterior C7 CPS was 30°–45°. The sagittal angle of the posterior C3–7 CPS was parallel to the corresponding upper endplate.