Fracture patterns and mechanisms in pedestrian motor-vehicle trauma: the ipsilateral dyad.

Pedestrians struck by motor vehicles have the highest mortality and morbidity rates of all motor-vehicle traumas. Fracture patterns and mechanisms were reviewed in a retrospective study of 115 consecutive patients. The most common fracture was tibia-fibula (39 patients), followed by pelvic (35 patients) and femur fractures (31 patients). A majority (90%) of long-bone fractures were the result of a direct-blow mechanism, and pelvic fractures were caused usually by lateral-compressive forces. Unstable pelvic and femur fractures both correlated with mortality (p less than 0.05), whereas tibia-fibula fractures (open or closed) did not. The triad of head, pelvis, and knee injuries traditionally associated with pedestrian motor-vehicle accident (MVA) victims was not found to occur with any statistical significance in this study group. Several characteristic fracture patterns were discovered: femur fractures associated with an accompanying pelvic fracture, and the ipsilateral dyad, an upper- and lower-extremity fracture on the same side, were found to occur with statistical significance (p less than 0.05). A lower extremity fracture warrants particularly close attention to the examination of the corresponding upper extremity, and a femur fracture should alert the clinician to the possibility of pelvic injury. The ipsilateral dyad has not been described previously in the literature and should be appreciated by physicians evaluating and treating pedestrian MVA victims.