Mechanisms of abdominal organ injury in seat belt-restrained children

Background. Previous research has identified key predictors of elevated abdominal injury risk in seat belt-restrained child vehicle occupants; however these data cannot be used to isolate specific mechanisms or sources of injury to suggest strategies for prevention. Methods: Using a large child-focused crash surveillance system, cases of seat belt-restrained children who sustained an internal abdominal injury in a frontal crash were studied using standard crash investigation protocols. A second group of cases of restrained children in similar crashes without abdominal injury was investigated. Medical, crash, and child characteristics of each case were analyzed in the context of known biomechanics of abdominal injury to determine the mechanisms of injury and associated kinematics. Results: Review of 21 cases of abdominal injury identified belt loading directly over the injured organ as the most common mechanism of injury. Three unique kinematic patterns were identified that varied by the initial position of the lap belt and kinematics of the upper torso. Sixty percent of the drivers and 90% of the other child occupants in these crashes sustained either no or minor injury. In the 16 no abdominal injury cases, all but one sustained external bruising to their abdomen and contact injury to the head and face. Conclusions: This evaluation of crashes in which belted children did and did not sustain abdominal injuries revealed key characteristics about their mechanism. In this data set, belt compression directly on the abdomen, manifested by improper initial placement of the seat belt, poor child posture, or misuse of the shoulder belt, resulted in abdominal injury in low-severity crashes in which other occupants sustained little injury. The cases pointed to control of torso excursion by consistent use of the shoulder belt and suggested that technologies such as lap belt pretensioners or belt-positioning booster seats might be a possible strategy, among others, for prevention.