Abstract
BACKGROUND: Unlike simple fractures, complex Type III odontoid fractures-characterized by intricate morphology and pathomechanics-pose significant management challenges. This study aims to evaluate the clinical and radiological outcomes of conservative and surgical treatment modalities for these complex fractures, with a focus on assessing factors influencing fracture union. METHODS: Following approval of our institutional review board, this retrospective observational cohort study was conducted. All Patients with complex Type III odontoid fractures who were managed at our center from June 2016 to December 2022 were assessed for eligibility. The primary outcome was union status. Secondary outcomes included the ASIA impairment scale, neck disability index (NDI), and complications. Logistic regression analysis was conducted to identify risk factors for adverse union outcomes. RESULTS: A total of 39 patients were included in the final analysis, with a mean age of 36.10 years. Nine patients were managed conservatively, 12 patients underwent anterior odontoid screw (AOS) fixation, and 18 patients received posterior fusion (PF). The rate of bony union varied significantly across the treatment groups, 100 % in the PF group, 58 % in the AOS group and 22 % in the conservative group (p = 0.0012). The NDI revealed superior functional outcomes in the PF group compared to the other groups (p = 0.0436). Failure of primary treatment was observed in seven patients (three from the conservative group and four from the AOS), necessitating secondary treatment with PF. Lateral mass gap >2 mm, coronal tilt >5°, and atlantoaxial instability >50 % were identified as significant risk factors for adverse union outcomes. CONCLUSIONS: Surgical treatment, particularly PF, offers superior outcomes in terms of union rates and functional recovery for complex Type III odontoid fractures. The identification of specific radiological measurements as significant risk factors for non-union underscores the need for detailed imaging and careful patient selection for conservative versus surgical management.