Abstract: Objective To investigate the surgical treatment and clinical results for the primary basilar invagination (BI) with atlantoaxial dislocation (AAD). Methods A retrospective study was performed. The study included 89 patients who had primary BI and AAD were surgically treated in our hospital from January 2008 to December 2011. There were 28 males and 61 females, aged between 10 and 69 years (mean 45.42 years). All patients were treated by the same 3-step surgical method. The first step, reduction of the AAD was performed by homemade odontoid repositor intraoperatively through posterior approach; the second step, AO stainless steel plates were fixed between the occiput and C2, 3 lateral mass screws; and the third step, occipitocervical fusion were completed by autologous iliac crest graft. Operation effect was recorded during follow-up period. Results Follow-up period was 6 to 48 months. Clinical symptoms were improved in 82.93% patients after the surgery. Japanse Orthopaedic Association (JOA) score increased from preoperative (8.80 ± 1.36) points to postoperative (15.35 ± 1.47) points (t = 17.225, P = 0.001). In general, satisfactory decompression and bony fusion were shown on postoperative radiological examinations for all patients. Compared with pretreatment data, the postoperative imaging measurement showed that the mean data of atlanto-dental interval (ADI, 9.22 mm vs 3.72 mm) and vertical dimension from the top of odontoid process to Chamberlain line (10.41 mm vs 3.23 mm) were all reduced, and the cervicomedullary angle (130° vs 150°) and space available of spinal cord (SAC, 11.13 mm vs 15.54 mm) were all improved. Conclusion The one-off surgery of posterior reduction technique and fixing between occiput and C2, 3 lateral mass screws is a safe, easy, and effective treatment for patients with primary BI and AAD. However, the final operative efficacy remains to be studied in long-term follow-up trial.

Key words: Platybasia, Dislocations, Atlanto-axial joint, Atlanto-occipital joint, Spinal fusion

摘要： 目的  探讨原发性颅底凹陷合并寰枢椎脱位的临床特点、外科手术治疗方式及临床效果。方法  回顾分析2008 年1 月-2011 年12 月住院治疗且经影像学检查明确诊断的89 例原发性颅底凹陷合并寰枢椎脱位患者的临床资料，男性28 例，女性61 例；年龄10 ~ 69 岁，平均45.42 岁。经后正中入路Ⅰ期施行复位器辅助寰枢关节复位，以两块AO 钢板连接枕骨与第2，3 颈椎侧块螺钉内固定，取自体髂骨行枕颈植骨融合，并随访观察手术效果。结果  共随访6 ~ 48 个月，大多数患者临床症状明显改善，日本骨科协会评分由术前的8.80 ± 1.36 增至术后的15.35 ± 1.47，手术前后比较差异有统计学意义（t = 17.225，P = 0.001）；手术改善率达82.93%。手术前后影像学测量平均值比较，寰齿间距（9.22 mm∶3.72 mm）和齿状突顶点至Chamberlain 线垂直距离（10.41 mm∶3.23 mm）减小，而延髓颈髓角（130°∶150°）和脊髓可用空间（11.13 mm∶15.54 mm）增加，4 项指标均不同程度改善。结论  术中Ⅰ期复位辅助植骨融合内固定术治疗原发性颅底凹陷合并寰枢椎脱位操作步骤简单，安全性高，疗效确切，但远期手术疗效尚有待长期随访观察。

关键词: 扁颅底, 脱位, 寰枢关节, 寰枕关节, 脊柱融合术