The clinical classification and surgical treatment choice of irreducible atlantoaxial dislocation

Abstract

Objective To investigate the clinical classification and surgical options for bone-fused irreducible atlantoaxial dislocation. Methods From November 2002 to December 2013, 20 cases of irreducible atlantoaxial dislocation were treated, including 8 males and 12 females, aged 22 to 57 years (mean 39 years). There were 6 cases without operation history and 14 cases with operation history, including 1 cases of anterior operation, 11 cases of posterior operation, and anterior and 2 cases of posterior combined approach. In 14 patients with surgery history, 13 cases had internal fixation residual, including 1 case of anterior plate and 12 cases of posterior screw rods. Under general anesthesia, the extensive fusion type was decompressed directly without restoration and immobilization, while the point fusion type was performed using soft tissue release, bone-fused point release, restoration, immobilization and fusion. 1 week, 3, 6, 12 months postoperatively and the annual review of the X-ray, CT and MR were checked, in order to evaluate the reduction, internal fixation, bone graft fusion and decompression of the spinal cord. The JOA scores of preoperative, postoperative and outpatient follow-up review were recorded. Results In all 20 patients, the extensive fusion type accounted for 5 cases, point fusion type 15 cases, while spontaneous fusion 6 cases, iatrogenic fusion 14 cases, including 3 cases of extensive fusion type and 11 cases of point fusion. In 5 cases of extensive fusion treated with anterior resection of anterior arch of atlas and the odontoid process decompression, postoperative MR showed that the spinal cord compression were completely eliminated, and reduction were achieved. The spinal cord and vertebral artery injury were not found. 1 case with cerebrospinal fluid leakage was cured after anterior internal fixation removal and posterior internal fixation. 5 cases of extensive fusion type and 14 cases of punctate fusion were followed up, ranged from 6 to 72 months (mean, 38 months). The JOA score was restored from preoperative average of 11 points to the last follow-up of 14 points. Even though no additional internal fixation was added, all 5 patients with extensive fusion showed no atlantoaxial intervertebral instability in follow-up period, and solid bony fusion of lateral atlantoaxial joint was obtained in 14 point fusion patients 6 months later. Conlusion The point fusion irreducible atlantoaxial dislocation can still get reduction after release and thoroughly removal of bony fusion point, while the extensive fusion irreducible atlantoaxialdislocation may still achieve good outcome by decompression. Key words: Atlanto-axial joint; Dislocations; Spinal fusion; Treatment outcome