Safety and Stability of a Combined C2 Screw Placement Strategy With Vertebral Artery Mobilization.
BACKGROUND: Although C2 pedicle screws are considered the gold standard for atlantoaxial fixation, the optimal fixation strategy for patients with high-riding vertebral arteries (HRVA) or narrow C2 pedicles (NC2P) remains controversial because of the increased risk of vertebral artery injury and the limitations of alternative fixation techniques. OBJECTIVE: To evaluate the safety, stability, and clinical efficacy of an individualized C2 screw fixation strategy incorporating vertebral artery mobilization for complex upper cervical anatomy. METHODS: A retrospective study was conducted in 312 patients who underwent C2 fixation between 2017 and 2025. Patients were categorized according to fusion method, screw laterality, and VA transposition requirement. Bone fusion rates and screw accuracy (Gertzbein-Robbins grading) were compared across groups using χ2, Fisher's exact, and multivariate logistic regression analyses to control confounders. RESULTS: All procedures were successfully completed without permanent neurovascular injury. At 6 months, the fusion rate with an atlantoaxial fusion cage was significantly higher than with interlaminar bone grafting (92.3% vs. 51.0%, p < 0.001). Unilateral C2 pedicle screw fixation combined with a contralateral alternative screw achieved comparable stability to bilateral fixation (p > 0.05). Screw placement accuracy was 100% clinically acceptable in normal anatomy and 60% in cases requiring VA mobilization, with no VA injury or blood flow compromise. CONCLUSION: The proposed multi-strategy C2 screw placement protocol-integrating fusion cage support and VA mobilization-achieves superior fusion, reliable fixation, and high safety, even in anatomically challenging conditions. This approach provides a reproducible and versatile solution for C2 instrumentation in complex craniovertebral junction surgery.