Atlanto-axial instability (AAI) is common in the connective tissue disorders, such as rheumatoid arthritis, and increasingly recognized in the heritable disorders of Stickler, Loeys-Dietz, Marfan, Morquio, and Ehlers-Danlos (EDS) syndromes, where it typically presents as a rotary subluxation due to incompetence of the alar ligament. This retrospective, IRB-approved study examines 20 subjects with Fielding type 1 rotary subluxation, characterized by anterior subluxation of the facet on one side, with a normal atlanto-dental interval. Subjects diagnosed with a heritable connective tissue disorder, and AAI had failed non-operative treatment and presented with severe headache, neck pain, and characteristic neurological findings. Subjects underwent a modified Goel-Harms posterior C1-C2 screw fixation and fusion without complication. At 15 months, two subjects underwent reoperation following a fall (one) and occipito-atlantal instability (one). Patients reported improvement in the frequency or severity of neck pain (P < 0.001), numbness in the hands and lower extremities (P = 0.001), headaches, pre-syncope, and lightheadedness (all P < 0.01), vertigo and arm weakness (both P = 0.01), and syncope, nausea, joint pain, and exercise tolerance (all P < 0.05). The diagnosis of Fielding type 1 AAI requires directed investigation with dynamic imaging. Alignment and stabilization is associated with improvement of pain, syncopal and near-syncopal episodes, sensorimotor function, and exercise tolerance.

寰枢椎不稳定性 (AAI) 在结缔组织疾病中很常见，例如类风湿性关节炎，并且在 Stickler、Loeys-Dietz、Marfan、Morquio 和 Ehlers-Danlos (EDS) 综合征等遗传性疾病中越来越被认识，这些疾病通常由于鼻翼韧带功能不全，表现为旋转性半脱位。这项经 IRB 批准的回顾性研究检查了 20 名 Fielding 1 型旋转半脱位受试者，其特征是一侧小关节前部半脱位，寰椎-牙齿间隔正常。被诊断患有遗传性结缔组织疾病和 AAI 的受试者经过非手术治疗失败，并出现严重头痛、颈部疼痛和特征性神经系统症状。受试者接受了改良的 Goel-Harms 后 C1-C2 螺钉固定和融合术，没有出现并发症。 15 个月时，两名受试者因跌倒（一名）和枕-寰椎不稳定（一名）而接受了再次手术。患者报告颈部疼痛的频率或严重程度有所改善 ( P < 0.001)、手和下肢麻木 ( P = 0.001)、头痛、先兆晕厥和头晕（全部P < 0.01）、眩晕和手臂无力（均P = 0.01）、晕厥、恶心、关节疼痛和运动耐量（均P < 0.05）。 Fielding 1 型 AAI 的诊断需要通过动态成像进行定向检查。对准和稳定与疼痛、晕厥和近晕厥发作、感觉运动功能和运动耐量的改善相关。