Risk factors of non-union in Anderson–D’Alonzo type III odontoid fractures with conservative treatment

The purpose of this study was retrospectively to analyze the risk factors for non-union in Anderson–D’Alonzo type III odontoid fractures with conservative treatment. 25 patients with type III fractures were analyzed. Coronal and sagittal tilt as well as sagittal and lateral mass gaps were measured by using computed tomography. The non-union group had significantly higher age, greater coronal tilt and lateral mass gap. Especially, the lateral mass gap was >2 mm in all cases with non-union. Higher age, coronal tilt, and lateral mass gap were significant risk factors for non-union.