To investigate the correlation between motor vehicle crash mechanisms and pelvic injury in front-seat occupants, we retrospectively reviewed the clinical records of, and had complete crash reconstructions performed for, 145 vehicular trauma patients with injury Severity Scores greater than 16 admitted to a level I trauma center. After excluding rear-seat and ejected occupants, 44 of the remaining 115 patients had pelvic injuries. We excluded acetabular fractures and classified the remaining 26 pelvic ring fractures by the system of Young and Burgess: 20 lateral compression (LC) fractures, five anteroposterior compression (APC) fractures, and one combined mechanical injury (CMI) fracture. Eighteen pelvic fractures were managed conservatively; eight required surgical intervention and four of those eight required emergent application of an external fixator for unresponsive hypotension. Trained investigation teams conducted the crash reconstructions, evaluating crash sites and vehicles with direct measurements of more than 500 variables. Calculations from these data, e.g., direction of impact and change in velocity at impact (delta V), were made with the CRASH III computer program and statistical analyses were performed using Chi-square and t tests. This information was then merged with the orthopedic evaluations.(ABSTRACT TRUNCATED AT 250 WORDS)