Direct posterior reduction and fixation for the treatment of idiopathic atlantoaxial dislocation

Abstract

Objective To report our surgical technique and results in the treatment of idiopathic atlantoaxial dislocation (IAAD) by using direct posterior reduction and fixation, without odontoidectomy and cervical traction. Methods Twenty patients of IAAD were operated on during May 2004 to December 2007. Before and after the operation, CT and MRI were used to measure and evaluate the degree of dislocation and neural compression. Two different screw fixation techniques were used depending on whether there was C1 assimilation; C1 lateral mass - C2 pedicle screws fixation was used for patients without C1 assimilation, otherwise, C2 pedicle -Occiput scews fixation was used. Intraoperative reduction was achieved by compressing the C2 spinous process anteriorly, or by distraction between C2 pedicle and occiput screws. Results All 20 patients were followed up from 6 to 48 months, among them, there was one death due to basilar artery thrombosis one week after the operation; in all the other 19 patients, symptoms were relieved markedly. All the postoperative radiological measurements were improved significantly (paired t test, in all groups, P < 0. 01 ). MRI showed good decompression of spinal cord and oblongata medulla in all 19 cases (CMA, P < 0.01 ); in 5 patients associated with Chiari's malformation and syringomyelia, syrinx was significantly shrinked in all patients. Conclusion Using posterior approach and intraoperative reduction and fixation technique, rather than anterior decompression through transoral odontoidectomy, for the treatment of IAAD is an effective, simple and relatively safe method. Key words: Atlantoaxial dislocation; Basilar invagination; Reduction; Fixation