Combined Fractures Involving the Odontoid and Unilateral Superior Articular Processes of the Axis: A Report of Three Cases and Literature Review

INTRODUCTION: A treatment strategy has not yet been established for combined fractures involving the odontoid and unilateral superior articular processes of the axis. Such injuries are rare, with only 17 reported cases in the literature. A lateral flexion force with a rotated position of the atlas on the axis is considered to be the mechanism of injury. CASE REPORT: Herein, we present three cases (two female; 1 male; and age range 65—years) of combined fractures involving the odontoid and unilateral superior articular processes of the axis, with a mean follow-up period of 17 months. Two patients were treated surgically, while one patient was treated non-surgically. In the present cases, two new findings were obtained regarding the mechanism of injury. First, both clockwise and counterclockwise rotated positions result in such fractures. Second, a comminuted-type fracture of the superior articular process of the axis was observed. Neck pain, limitations in the range of motion of the neck, and torticollis remained after treatment in non-surgical cases, while there were no such symptoms in surgical cases. CONCLUSION: Of importance, the combined fractures shown in the current study may be considered as Type III odontoid fractures when diagnosed only by X-rays. Therefore, when observing a great dislocation, the presence of comminuted fractures or torticollis of the odontoid should be ascertained on X-ray and computed tomography images (especially coronal images). To avoid lingering symptoms in the neck, surgery is recommended for the treatment of these fractures.