A novel bone screw implantation strategy in C1-2 instability: a framework for evolving high cervical spine surgery

Fixation surgery for atlantoaxial instability (AAI) or atlantoaxial subluxation is recognized as a complex and high-risk procedure, prompting the development of various fixation techniques. In this preliminary study, we evaluated the safety and accuracy of C1-2 pedicle screw insertion using our developed planning software and 3D-printed guiding templates. We also analyzed feasibility with free-hand techniques to identify an optimal strategy for atlantoaxial fixation. We used a self-developed 3D planning method, along with guiding template techniques, for pedicle screws in high cervical vertebra fixation. A small cohort of thirteen patients in Group 1 received free-hand screw placement, while seventeen in Group 2 performed using the planning and guiding system. We analyzed demographics, complications, and screw placement precision. We compared the demographics, operative time, and blood loss between the two groups. Complications occurred in patients from Group 1, but none in those from Group 2. Most Group 2 patients underwent the C1 and C2 pedicle screws approach, which showed significantly higher screw placement safety. Both pedicle screws applied in C1 and C2 are preferable to occipitocervical fusion when feasible. The planning strategy and its associated guiding system improve the implanted screws precision and safety of pedicle screw placement, particularly in cases with high-riding vertebral arteries. When the C2 pedicle diameter exceeds 3 mm, we safely perform the C2 pedicle screws. This method supports more precise preoperative planning for atlantoaxial instability.