OBJECTIVE This study aimed to compare the clinical results of using posterior fixation and fusion with or without anterior decompression to treat os odontoideum with atlantoaxial dislocation. METHODS Twenty-five consecutive patients with os odontoideum were included in this study. Sixteen patients with reducible atlantoaxial dislocation were treated by single-level posterior fusion and stabilization; the other 9 were treated with posterior fusion and stabilization combined with transoral decompression. Pre- and postoperative CT scans and MR images were obtained. RESULTS Twenty-four patients were followed for 24-54 months (average 36.5 months). Postoperative CT scans indicated that all pedicle screws were placed satisfactorily except in 2 cases, in which the screws slightly penetrated the transverse foramen. Postoperative MR images demonstrated that sufficient decompression of the spinal cord was obtained in all patients. Complications included 1 case each of pedicle screw breakage, pharynx ulcer, and persistent pharynx discomfort. Statistical analysis of all cases revealed that mean Japanese Orthopaedic Association scores improved from a preoperative score of 10.2 (range 7-13) to a postoperative score of 15.6 (range 11-18). CONCLUSIONS Patients who have os odontoideum with a reducible atlantoaxial dislocation can be effectively treated with single-level posterior fusion and stabilization. Combined transoral decompression and posterior fusion and stabilization is recommended for those with irreducible atlantoaxial dislocation.
Keywords: JOA = Japanese Orthopaedic Association; VA = vertebral artery; VAS = visual analog scale; atlantoaxial dislocation; cervical; os odontoideum; posterior fusion; transoral decompression.