Evaluation of a novel C2 pedicle screw insertion technique: a retrospective comparative clinical study and finite element analysis

C2 pedicle screws (C2PS) are extensively used in the treatment of upper cervical spine disorders owing to their superior mechanical properties. However, incorrect screw insertion in the C2 pedicle can lead to catastrophic consequences due to the proximity to critical structures such as the vertebral artery groove and spinal cord. There is currently no universally accepted method for precise C2PS placement. In this study, we evaluated a novel free-hand C2PS insertion technique that uses the superior margin of the C2 lamina and the medial margin of the C2 pedicle as landmarks, thereby avoiding routine exposure of the C2/C3 facet joint capsule. Compared with the traditional Harms technique, the novel method reduced the transverse screw angle and sagittal screw angle, which may facilitate screw insertion in a limited operative field. The overall rate of pedicle breach was not significantly increased. Finite element analysis further showed comparable fixation strength between the two techniques in the modeled normal C2 anatomy. In summary, for anatomically suitable C2 pedicles, the novel C2PS insertion technique provided comparable radiographic accuracy and similar biomechanical stability to the Harms technique, while requiring smaller insertion angles and less lateral exposure.