摘要目的:建立术前预估寰枢椎理论复位距离及复位角度的颅底凹陷寰枢椎复位几何模型，并验证其临床应用价值。方法:回顾性分析2018年5月至2020年5月重庆医科大学附属第一医院神经外科收治的35例颅底凹陷合并寰枢椎脱位患者的临床资料。其中男性5例，女性30例，年龄（48±15）岁（范围：19~69岁）。均以患者颈椎CT正中矢状位截面为蓝本建立寰枢椎复位几何模型，术前根据几何模型测算相关数据，并在术中选择相应高度的融合器置入C 1~2小关节间，进行量化复位。收集患者由模型测算的理论复位值、术后实际复位值、术后恢复情况与并发症情况。采用配对样本 t检验比较理论和实际复位值的差异，以验证此几何模型的准确性。 结果:所有患者枢椎理论垂直复位距离为（5.79±2.96）mm（范围：1.52~10.96 mm），实际垂直复位距离为（7.43±2.96）mm（范围：1.40~12.77 mm），二者差异无统计学意义（ t=-1.96， P=0.069）；理论复位角度为（10.80±2.24）° （范围：7.09~14.86°），实际复位角度为（10.64±7.00）°（范围：3.50~20.50°），二者差异无统计学意义（ t=0.09， P=0.933）。术后6个月随访时，35例患者均获得满意融合，症状较术前明显缓解。无内固定系统移位、断裂，伤口感染等并发症发生。 结论:此几何模型可在术前预估枢椎垂直复位距离和复位角度，为术中置入小关节间融合器的高度、悬臂压棒的角度及复位程度提供参考。

abstractsObjectives:To establish a geometric model of the atlantoaxial dislocation and basilar invagination reduction,and examine its value for clinical application.Methods:A retrospective analysis of 35 patients with atlantoaxial dislocation and basilar invagination admitted to the Department of Neurosurgery,First Affiliated Hospital of Chongqing Medical University from May 2018 to May 2020 was conducted.There were 5 males and 30 females,aged (48±15) years(range: 19 to 69 years). The geometric model of the atlantoaxial reduction was established based on the mid-sagittal section of the cervical spine. The relevant data were calculated according to the geometric model before operation,and the fusion cage of the corresponding height was placed into C 1-2 facet joint of patient for quantitative reduction. The theoretical reset value, actual reset value, postoperative symptoms and complications were collected. The paired t-test was used to compare the difference between theoretical and actual reset value to verify the reliability of the geometric model. Results:The theoretical vertical reduction distance of all patients was (5.79±2.96) mm(range:1.52 to 10.96 mm),and the actual vertical reduction distance was (7.43±2.96)mm(range: 1.40 to 12.77 mm),and there was no statistical difference between them( t=-1.96, P=0.069).The theoretical reduction angle was (10.80±2.24)°(range: 7.09 to 14.86°), the actual reduction angle was (10.64±7.00)°(range: 3.50 to 20.50°),and there was no statistical difference between them ( t=0.09, P=0.933). At 6 months follow-up, 35 patients achieved satisfactory atlanto-axial joint fusion, and the symptoms were relieved. No internal fixation system displacement, fracture, wound infection and other complications occurred. Conclusion:This geometric model can estimate the vertical reduction distance and the reduction angle of the axial before operation,and provide a reference for the height of the fusion cage so as to avoid under or over-reduction.