Anterior arch resection combined with posterior fixation for odontoid malunion

Abstract

Objective To study the clinic efficacy of anterior arch resection, atlantoaxial joint release combined with posterior fixation and fusion for odontoid malunion associated with irreducible atlantoaxial dislocation. Methods From February 2007 to February 2012,6 patients (5 males, 1 female) were diagnosed with odontoid malunion associated with irreducible atlanto-axial dislocation. The ages ranged from 36 to 57 years (average 45.5 years). There were traumatic histories and spinal injury symptoms in all patients. The preoperative Japanese Orthopaedic Association (JOA) score was 7.5±2.2 (range, 4-10), and the space available for the cord (SAC) of preoperation ranged from 5 to 11 mm (8.1±2.5 mm). All cases received anterior arch resection, atlantoaxial joint release combined with posterior fixation and fusion. They all wore cervical collar for 3 months after operation. The function of spinal cord was observed and atlanto-axial reduction and fusion was evaluated by postoperative X-ray and CT scan. Results All the patients underwent surgery successfully and their atlanto-axial reductions were complete. 6 cases were followed up for 12-20 months (average 16 months). No instrument failure or dislocation was observed during follow-up. Bone graft fusion was achieved 3 months after operation. The JOA score at the last follow-up was 10-15 (average 14.7±2.1), which showed significant difference compared with preoperative score. The average improving rate of JOA was 75.5%. The SAC at the last follow-up was 11-17mm (average 13.5±2.6 mm), which had significant difference compared with preoperative score. On the 5th day after operation, one patient experienced exudation and poor healing of posterior incision which was resolved by lateral position avoiding compression of wound. The posterior incision healed within 3 weeks. On the 3th day after operation, apathy occurred in one case and laboratory tests showed hypernatremia and hypokalemia. The consciousness of the patient recovered within 1 day after venous fluid infusion timely. Conclusion Anterior arch resection, atlantoaxial joint release combined with posterior fixation and fusion is a safe and efficient method with satisfactory short-term outcome for odontoid malunion associated with irreducible atlantoaxial dislocation. Key words: Odontoid process; Spinal fractures; Fracture healing; Atlanto-axial joint; Dislocations; Spinal cord compression