Traumatic avulsion fracture of the occipital condyles and clivus with associated unilateral atlantooccipital distraction.

We describe an unusual tramatic fracture/distraction injury of the craniovertebral junction, which the patient survived. It is postulated that this represents an example of the spectrum of fracture dislocation injuries that may occur at, and adjacent to, the atlantooccipital joints. Avulsion fractures in this region , associated with atlantooccipital dislocation, may be more common than previously suspected, particularly in adults, in whom supporting ligaments are strong and not apt to rupture. Thin-section CT with coronal and sagittal reformation can best visualize these fractures , while MR imaging is useful in the assessment of the adjacent soft tissues.