Autopsy data from 304 fatally injured motorcyclists (60 helmeted and 244 unhelmeted) were analyzed for the incidence, location, and mechanism of injury to the upper cervical spine, Atlas (C1) and Axis (C2). Findings include 160 incidences of subluxation, 35 dislocations and 28 fractures. The mechanisms and relationship of these injuries to head impacts, head and neck motion, and closely related injuries were examined. The neck motions often associated with Atlas or Axis injury were hyperextension and lateral bending. Injuries to the Atlas and Axis are relatively infrequent in the broad spectrum of motorcycle accidents. In their subset of fatal accidents these injuries are often found, particularly particularly during detailed autopsy examination. Without careful examination, injuries in the region of the Atlas and the Axis are often overlooked, indicating that they may be more frequent then reported in many studies.
Abstract