Traumatic lesions of the occipitoatlantoaxial complex.

Injuries of the occipitoatlantoaxial complex are relatively rare but form a group of ligamentous and bony lesions that may unnecessarily confuse the clinician. Since fractures of the dens and traumatic spondylolisthesis of the axis have been well described in a number of large series, this article concentrates on the lesions less frequently seen and described. The ligamentous injuries are occipitoatlantal dislocation, rupture of the transverse ligament, and atlantoaxial rotatory fixation. The bony injuries are fractures of the occipital condyles, atlas, and the lateral masses of C2. The incidence, diagnostic criteria, and treatment modalities depend on the nature of localization of the traumatic lesions.