Safe placement of lateral mass screw in the subaxial cervical spine: a case series

Abstract

All screws were inserted into the lateral mass of C3-C6 cervical vertebrae following the current technique. Post-operative CT scans confirmed all screws inserted into the safe zone and relative safe zone of the lateral mass without any screw placed into the transverse foramen. The angle between the lateral mass screw and the vertical line was 40.49 ± 5.44 degrees on the axial CT images. Twenty-four patients were followed up for an average of 25.79 months (range, 20-30 months), and 22 cases evaluated as no or mild disability. According to the JOA score, NDI score and NDI ranking system, the postoperative function of the patients was significantly better when compared with their preoperative corresponding data (all p < 0.001) CONCLUSION: Inserting lateral mass screw following this new strategy is safe and easy to perform without any screw-related neurovascular complications, which contribute to the rigid fixation of the subaxial cervical spine and the satisfactory functional recovery.

Subaxial Cervical Pedicular Screw Insertion via the Nonanatomic Axis: Technical Notes and Preliminary Clinical Report

“…Inserting screws into the lateral mass is relatively easier and safer than insertion into the cervical pedicle, hence, increasing popularity of LMS fixation. 1 - 4 However, the biomechanical advantage of CPS cannot be overlooked when correction of cervical deformity, or other rigid multiple segmental reconstructions, are required. 5 The pedicle of the subaxial cervical spine presents a smaller diameter and a larger convergence angle than those of the thoracic or lumbar vertebrae, suggesting that CPS insertion poses a risk to the neighboring neurovascular structures.…”