Anderson-Montesano Type III Occipital Condyle Fractures: Insights From a Multicenter Cohort.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: To describe a multicenter cohort of patients with type III occipital condyle avulsion fractures, emphasizing mechanical stability and treatment strategies. SUMMARY OF BACKGROUND DATA: Occipital condyle avulsion fractures are rare, potentially unstable, and historically underreported. METHODS: A retrospective study was performed across 4 spine centers, including patients with acute traumatic occipital condyle avulsion fractures treated between June 2017 and April 2024. Clinical and imaging variables were reviewed. RESULTS: Thirty-two patients with Anderson-Montesano type III fractures were identified, predominantly male (81.3%), with a mean age of 36.6 years. High-energy trauma accounted for most cases (96.9%), mainly motor vehicle accidents (78.1%). Craniocervical instability was present in 9 patients (28.1%), all treated with posterior occipitocervical fusion; the remaining were managed nonoperatively. CT confirmed fusion in 20 patients (80%), with a mean healing time of 99.2 days. Median follow-up was 702 days. Instability was significantly associated with severe head trauma, unstable C1-C2 injuries, and MRI-documented ligamentous or soft tissue injury. CONCLUSION: Most occipital condyle avulsion fractures are stable and suitable for conservative management, but a relevant subset demonstrates craniocervical instability requiring surgical stabilization. MRI and dynamic radiographs help identify high-risk cases.