Biomechanical aspects of pelvic and hip injuries in road traffic accidents.

The mechanism of pelvic fractures has been well documented from radiographs but little is known of the forces required to produce these injuries. We examined 40 cases of pelvic injury sustained in road traffic accidents where the direction of impact and the velocity differential was known. In frontal impacts, indirect shear injuries of the pelvis were prominent, while in side impacts, lateral compressive injuries occurred. With increasing velocity differentials and vehicle deformation and intrusion, more severe pelvic injury occurred, often in association with significant head, chest, and lower limb injuries. Side impacts were noted to produce more severe injuries at lower velocity differentials when compared with frontal crashes.