Occipital condyle fracture and ligament injury: imaging by CT.

The true incidence of fracture of the occipital condyles is unknown. It may be associated with instability at the craniocervical joint. CT is the modality of choice for the demonstration of these fractures, but its use for imaging of the associated ligament injury has not been reported. In order to demonstrate normal anatomy, occipital condyle fracture and ligament injury, and to estimate the incidence of this lesion, 21 children and young adults with high-energy blunt craniocervical injury were examined prospectively. Thin-slice, axial, contiguous, CT was performed from the base of C2 to above the foramen magnum. Bone and soft tissue windows and coronal, sagittal, and curvilinear 2D reconstructions were performed. Five occipital condyle fractures were identified in four patients (19 %), with demonstration of alar ligament injury in two cases and local hematoma in one. In four, artifacts or rotation precluded assessment of ligaments. In all remaining cases normal bone and ligament anatomy was demonstrated. Fracture of the occipital condyles following craniocervical injury is not uncommon in children and young adults. Normal bone and ligament anatomy and pathology can be safely and clearly demonstrated in seriously injured patients and others using this CT technique. Increased awareness of this entity and a low threshold for performing CT should avoid the potentially serious consequences of a missed diagnosis.