Lateral mass intra-pedicular screw fixation for subaxial cervical spines-An alternative surgical technique

Background: Lateral mass screw (LMS) and transpedicular screw (TPS) techniques are the two major options for performing posterior cervical fusion of the subaxial cervical spine. Although these two techniques can cover the vast majority of patients who require posterior fixation of the cervical spine, they are not without their limitations. Objective: The objective of this study is to introduce a novel technique, lateral mass intrapedicular screw (LMIS) fixation, for posterior subaxial cervical spine (C3-C6) fixation. Materials and Methods: The starting point of the screw is defined as the midpoint of the lateral mass. In the axial plane, the screw is angled at 20°-25° with respect to the midline of the spinous process. In the sagittal plane, the screw is directed toward the rostral quarter (zone 1) of the vertebral body and placed within the pedicle. A preliminary, proof-of-concept experiment was performed using a bone model created with synthetic bone and computed tomography images before performing the operation on a patient. Results: During the preliminary experiment, insignificant breaching of the inner cortex of the pedicle was observed with one of the screws. However, no other screws breached the inner cortex in the same manner during the preliminary experiment or during the operation, and the intraoperative fixation was strong. Conclusion: LMIS is a relatively simple and safe technique that can be performed for the fixation of subaxial cervical spines with screws that are longer than those used in LMS. We believe that this technique may join the two existing techniques to become a common alternative technique, particularly for patients with poor bone quality.