C1-ring osteosynthesis for Jefferson fracture: a multi-institutional retrospective case series

PURPOSE: C1-ring osteosynthesis is gaining attention as a motion-preserving alternative for treating type III Jefferson fracture. This study evaluated its clinical and radiological outcomes, especially in cases involving partial transverse atlantal ligament (TAL) injury. METHODS: This retrospective study reviewed patients who underwent C1-ring osteosynthesis for traumatic type III Jefferson fracture at two institutions between January 2011 and December 2024. Preoperative and postoperative medical records, radiographs, magnetic resonance imaging, and computed tomography were reviewed to assess fracture type, TAL injury, anterior atlantodental interval (AADI), and posterior atlantodental interval (PADI). RESULTS: Eight patients (mean age, 49.1±20.0 years; 87.5% male) were included. Seven patients (87.5%) had type III Jefferson fractures, and one patient had a type III Jefferson fracture with lateral mass involvement. Partial TAL injury was identified in six patients. The mean follow-up period was 40.0±9.9 months. No postoperative neurological deficits or surgery-related complications were reported. Complete C1 ring fusion was achieved in six patients (75.0%) within 13.3±8.5 months. Two patients achieved fusion only at the posterior arch, with the anterior arch remaining unfused but without displacement. At the last follow-up, the C2-C7 Cobb angle was -17.7°±6.6°, and the cervical range of motion was 59.1°±22.6°. Seven patients (87.5%) had a flexion AADI greater than 3 mm; however, the difference in AADI between flexion and extension was within 2 mm, and the PADI was maintained at an acceptable level (16.0±1.2 mm). CONCLUSIONS: C1-ring osteosynthesis provided effective anatomical reduction, solid fusion, and favorable preservation of cervical motion in patients with type III Jefferson fracture, including those with partial TAL injury. These findings support its clinical utility as a motion-preserving alternative to posterior intersegmental fusion. Prospective studies with larger cohorts and comparative controls are warranted to validate these results.