Unstable hangman's fractures.

One hundred and seventy consecutive multiple trauma victims were studied postmortem by radiography and direct inspection at autopsy for the presence of cervical spine injuries. Of the total 38 fractures and/or dislocations, eight had bilateral pedicle fractures of the axis. Only atlanto-occipital dislocations were more frequently encountered. Dissection of six of the eight spines with hangman's fractures showed variable osseous and ligamentous injuries. In only two of the eight cases were significant ligamentous structures sufficiently intact to prevent gross displacement on flexion and extension. In three of the specimens complete laceration of the upper cervical spinal cord was found. Unstable hangman's fractures are a common fatal cervical spine injury in multiple trauma victims.