One-off surgery of posterior reduction and fixation for the treatment of basilar invagination with atlantoaxial dislocation

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. DOI：10.3969/j.issn.1672⁃6731.2012.04.013