Characteristics of Cervical Sagittal Alignment at Different C0–C2 Correcting Angles in Fusion Treatment of Atlantoaxial Dislocations

To explore the appropriate range of C0-C2 correction angles by analyzing cervical sagittal alignment parameters and evaluating clinical outcomes.The preoperative and postoperative radiographs, visual analogue scale, Japanese Orthopedic Association score, and neck disability index of 65 atlantoaxial dislocation patients were retrospectively collected. The C0-C2 angle, C2-C7 angle, and cervical sagittal vertical axis (cSVA) were measured from the radiographs, and an assessment of cervical degenerative disc disease was made. According to the 2-year postoperative C0-C2 angles, all patients were categorized into a <10° subgroup, 10°-20° subgroup, and >20° subgroups.The postoperative C2-C7 angles and cSVA of the 10°-20° subgroup were significantly different from those of the <10° subgroup. The Japanese Orthopedic Association score of the 10°-20° subgroup was significantly different from those of the <10° and >20° subgroups. All patients (26/26) in the 10°-20° subgroup exhibited a cSVA 0-40 mm, 25% of patients (6/24) in the >20° subgroup exhibited a cSVA >40 mm, and 40% of patients (6/15) in the <10° subgroup showed a cSVA <0 mm. The postoperative incidence of cervical degenerative disc disease did not increase in the 10°-20° subgroup.Atlantoaxial dislocation patients with different C0-C2 postoperative angles had different cervical sagittal alignments and clinical outcomes. In our study, the patients within the C0-C2 10°-20° subgroup exhibited superior clinical outcomes and cervical sagittal alignment.