Pelvic fracture in multiple trauma: classification by mechanism is key to pattern of organ injury, resuscitative requirements, and outcome.

Three hundred forty-three multiple trauma patients with major pelvic ring disruption were studied and subdivided into four major groups by mechanism of injury: antero-posterior compression (APC), lateral compression (LC), vertical shear (VS), and combined mechanical injury (CMI). Acetabular fractures which did not disrupt the pelvic ring were excluded. The mode of injury was: MVA, 57.4%; motorcycle, 9.3%; fall, 9.3%; pedestrian, 17.8%; crush, 3.8%. The LC and APC groups were divided into Grades 1-3 of increasing severity. The pattern of organ injury: including brain, lung, liver, spleen, bowel, bladder, pelvic vascular injury (PVASI), retroperitoneal hematoma (RPH) and complications: circulatory shock, sepsis, ARDS, abnormal physiology, and 24-hr total fluid volume administration were all evaluated as a function of mortality (M). As LC grade increased from 1 to 3 there was increased % incidence of PVASI, RPH, shock, and 24-hr volume needs. However, the large incidence of brain, lung, and upper abdominal visceral injuries as causes of death in Grade 1 and 2 fell in LC3, with limitation of the LC3 injury pattern to the pelvis. As APC grade increased from 1 to 3 there was increased % injury to spleen, liver, bowel, PVASI with RPH, shock, sepsis, and ARDS, and large increases in volume needs, with important incidence of brain and lung injuries in all grades. Organ injury patterns and % M associated with vertical shear were similar to those with severe grades of APC, but CMI had an associated organ injury pattern similar to lower grades of APC and LC fractures. The pattern of injury in APC3 was correlated with the greatest 24-hour fluid requirements and with a rise in mortality as the APC grade rose. However, there were major differences in the causes of death in LC vs. APC injuries, with brain injury compounded by shock being significant contributors in LC. In contrast, in APC there were significant influences of shock, sepsis, and ARDS related to the massive torso forces delivered in APC, with large volume losses from visceral organs and pelvis of greater influence in APC, but brain injury was not a significant cause of death. These data indicate that the mechanical force type and severity of the pelvic fracture are the keys to the expected organ injury pattern, resuscitation needs, and mortality.