Surgical Management of Unstable Atlas Fractures: A Single Institutional Retrospective Review with Comparison of Occipitocervical and Atlantoaxial Fusion Outcomes.

Background: Atlas fractures represent 25% of craniocervical injuries, most common in elders. Unstable first cervical vertebra fractures with lateral mass displacement require surgical fixation. Options include atlantoaxial fusion (AAF) or occiput-cervical fusion (OCF), each have their respective merits and detractors. Here, we compare the clinical and neurological outcomes of patients with unstable atlas fractures treated with AAF and OCF.

Methods: A retrospective review of patients with unstable atlas fractures that underwent either AAF or OCF between 2005 and 2023 was performed. Demographics, clinical characteristics, radiographic parameters, and outcomes were collected. Cervical sagittal balance was measured by O-second cervical vertebra (C2 or axis) angle, C2-7 lordosis, and C2-7 sagittal vertical axis (SVA).

Results: Forty-four patients with unstable atlas fractures were included (25 underwent AAF and 19 OCF). The median age was 73 years, and 52% were male. Demographics, mechanism of injury, and other clinical characteristics were similar. Landell's type 2 atlas fractures and lateral mass displacement were significantly in the OCF group. Median number of levels was significantly greater in the OCF group (3 vs. 2 in AAF, P=<0.001). C2-7 lordosis was less in OCF versus AAF (P = 0.045). SVA was less in the AAF group versus OCF (P = 0.044). Cervical SVA was decreased 4.5 mm in average in the AAF group versus 5.2 mm increase in OCF (P = 0.040). There were no significant differences in the rates of postoperative complication, surgical revision, or neurologic function.

Conclusions: OCF results in significant loss of lordosis and increase in cervical SVA relative to AAF, which may impact long-term quality of life and disability not directly measured in this study.