A 32-year-old man was injured in a pedestrian-motor vehicle collision. He was found with drowsy mentality and neu- rological deficit of hemiparesis at the accident scene. Three-dimensional computerized tomography(3-D CT) was performed to confirm the diagnosis of AOD and precisely evaluate the magnitude of displacement. Magnetic resonance imaging(MRI) clearly showed a disruption of the ligamentous structures which play a role as the primary stabilizers of the cranium on the cervical spine. Two weeks after the accident, posterior occiput-alas-axis fixation was performed. The surgical technique was thought to be safe to perform and resulted in immediate stability. Solid fusion was achieved 5 months after surgery. He was recovered progressively over a period of 6 months. Twelve months after surgery, no neurological deficit was present except for slightly right sided hemiparesis.
