TREATMENT FOR FRACTURES OF THE ODONTOID PROCESS

Abstract

Between 1982 and 2000, 37 cases of fractures of the odontoid process were treated at Hirosaki University Hospital. There were 16 females and 21 males, with an average age of 43.9 and 37.7 respectively. Twenty-three of 37 were type II and 14 were type III by the classification of Anderson and D’Alonzo. Eight of type II were old fractures. Nineteen of them were injured in traffic accidents, 9 in accidental falls from a height, 4 by falling down, 2 in lumbering accidents and 3 by unknown causes. Severe neurological disorders were recognized in 7, mild in 12 and 22 had no neurological disorders. Neurological disorders were correlated with SAC (space available for spinal cord) at C1-2. Twenty-two of type II (95.7%) and 10 of type III (71%) were treated surgically. Surgical methods were anterior screw fixation of the odontoid process in 7, anterior atlanto-axial joint fixation in 3, posterior atlanto-axial joint fixation in 5, posterior occipito-cervical fusion in 3, anterior and posterior combined fixation of the atlanto-axial joint in 2 and others in 2. Bone union was obtained in 18 (81.8%) of type II and 10 (100%) of type III by the primary operations. There was no nonunion in anterior screw fixation cases. Nonunion occured in one of type II (100%) and 2 of type III (50%) treated nonoperatively. Two of them were operated for nonunion. One of them remained nonunion by two additional operations. No case of nonunion showed neurological deterioration for 91.8 months after treatment on average. Anterior direct screw fixation of the odontoid process is superior to the other methods in the point of immobilization of the odontoid fragment without limiting the motion of the atlanto-axial joint. We recommend anterior direct screw fixation of the odontoid process as a first choice of the surgical method for fresh fractures of the odontoid process in cases with reduced fragments.