Pelvic fracture mechanism of injury in vehicular trauma patients

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 (AV), 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. We found that: (1) 72% of the pelvic fractures occurred in automobiles with gross vehicular weights less than 2700 lb (compact and subcompact) (p = 0.05); (2) the AV was lower for lateral impacts than for frontal impacts (24 mph vs. 32 mph, respectively; p = 0.0005); (3) more victims of lateral than frontal impacts suffered pelvic fractures (50% vs. 7.5%, respectively, p = 0.0001); (4) more victims of lateral than frontal impacts suffered LC injuries (83% vs. 17%, respectively; p < 0.0001); and (5) LC-II and LC-III fractures tended to occur at higher AVs than did LC-I fractures (29.0 mph vs. 23.5 mph, respectively). We concluded that there was a direct correlation between pelvic injury and vehicular mechanism of injury, substantiating the pelvic injury classification system of Young and Burgess, and that there is a need for additional side impact protection in motor vehicles.