Anterior cervical subluxation: an unstable position.

The radiologic signs of cervical anterior subluxation are subtle. Even when recognized, the injury may not be considered significant. However, anterior subluxation is the most unstable cervical spinal injury. The two case histories illustrate instability of the cervical spine in this type of injury. The radiologically diagnostic features on the lateral radiograph are described and the recognition of instability on mobility studies is discussed.