Shoulder belt-induced flexion-distraction fractures of the cervical spine

Serious and fatal injuries have been attributed to poorly designed or improperly worn seat belts. This study reports on a series of catastrophic cervical spinal injuries caused by shoulder belt impingement on the anterolateral neck in frontal collisions. This is a particular hazard for children and small adults. The mechanism of injury for the reported cervical flexion-distraction fractures is analogous to the mechanism described for thoracolumbar flexion-distraction injuries (Chance-type fractures) caused by impingement of the lap belt on the abdomen of occupants in frontal crashes as evidenced by contusions and/or abrasions to the anterolateral neck in afflicted patients. The impingement of the belt on the neck fixes spinal segments at and below the level of impingement and shifts the centre of rotation of the spine anteriorly, thus concentrating forces above the level of impingement and amplifying distraction moments posterior to the belt. These cases demonstrate that poor shoulder belt fit is not just a comfort issue, but a very significant safety issue.