Atlantoaxial mobility after screw fixation of the odontoid: a computed tomographic study

Between 1979 and 1989, anterior screw fixation of the odontoid process was performed in 16 patients with fractures of the odontoid. One patient died suddenly 2 days after the operation. Postmortem examination could not disclose the cause of death. No other complication was noted. We followed 13 patients. At examinations 7 to 82 months after injury, all fractures were consolidated in reduced position. In all patients, a functional computed tomographic (CT) examination of the atlantoaxial rotation was performed. Atlantoaxial rotation measurement ranged from 7 to 38 degrees to the right (average: 25.2 degrees) and 7 to 41 degrees (average: 24.1 degrees) to the left side. Five patients presented a normal range of atlantoaxial rotation, 29 to 41 degrees; 3 had a rotation of 20 to 28 degrees; 3 a rotation of 10 to 20 degrees; and in 2, rotation was less than 10 degrees to one side. Our results suggest that anterior screw fixation is the therapy of choice for Type II and cephalad Type III dens fractures. However, significant complications have been reported by other authors. Therefore, a careful surgical technique is mandatory, and contraindications should be respected.