Posterior C1-C2 screw-rod fixation and autograft fusion for the treatment of os odontoideum with C1-C2 instability

Objective: To report our experience treating os odontoideum with C1-C2 instability via C1-C2 screw-rod fixation and autograft fusion and to explore the clinical efficacy of such a treatment strategy. Patients and methods: We retrospectively reviewed the medical records of patients who were diagnosed with os odontoideum with C1-C2 instability and treated by posterior C1-C2 screw-rod fixation and fusion. Neurological deficits were measured with the Japanese Orthopedic Association (JOA) scoring system and neck pain was assessed using the Visual Analogue Scale (VAS) score. Fusion was determined based on the presence of bridging bone in computed tomography (CT) imaging, whereas stability was determined based on the lack of movement in dynamic radiographs. Results: Thirty-two patients (18 males) were included in the study. The surgery was successfully accomplished in all patients. Thirty (93.8%) patients had confirmed C1-C2 bony fusion in CT images and all patients (100%) were stable in dynamic radiographs. The mean preoperative JOA score was 14.3 +/- 1.4 (range 11-16); at the final visit, it increased to 16.2 +/- 0.8 (range 14-17) (p < 0.001). The mean preoperative VAS score was 3.8 +/- 0.7 (range 3-5) and decreased at the final visit to 1.0 +/- 0.6 (range 0-2) (p < 0.001). Conclusion: Our treatment strategy (C1-C2 screw-rod fixation and autograft fusion) can achieve excellent clinical results with minor complications for patients with os odontoideum with C1-C2 instability.