In-depth Field Investigations of Belt-restrained Children in Farside Crashes

Recent attention has focused on adults in farside crashes but little attention has been given to children in farside crashes. Thus, we sought to elucidate Injury Causation Scenarios (ICS’s) in children in center and farside seat positions. Crash investigation cases were drawn from the Partners for Child Passenger Safety Crash Investigation database, and the Crash Injury Research and Engineering Network database. Included in the study were children aged 4 to 15 years, involved in a side impact crash, seated on the center or farside in the rear rows, restrained by a seat belt alone (no booster seats or side airbags) and who received an AIS 2+ injury. Excluded cases were those where the only documented AIS 2+ injury was an altered state of consciousness (concussion, amnesia, or brief loss of consciousness). Seventeen cases met the inclusion criteria for this study. The three most frequently injured body regions to receive an AIS 2+ injury were: head, abdomen, and thorax, with thoracic injuries being quite rare. Intracranial injuries included cerebral contusions, subarachnoid hematoma/hemorrhage, edema, and extradural/epidural hematoma. Skull and facial injuries consisted of vault, orbit and maxillary fractures. Eight occupants had torso injuries: lung contusion, clavicle fracture, spleen laceration or rupture, liver laceration or contusion, and laceration or contusion to the digestive tract organs of the lower abdomen. Our results indicate that injury patterns and mechanisms are unique to children, and thus require a mitigation approach different than the adult. Of note, thoracic injuries, which are common in adult farside crashes, are relatively rare in pediatric farside crashes. Farside abdominal injury patterns suggest a lap belt submarining mechanism in children, injuring primarily the intestinal viscera. These findings further support that children require a different approach to injury mitigation than the adult, and have abdominal injuries in farside crashes that may be addressed by injury mitigation solutions for frontal impact. INTRODUCTION Successful development of side impact safety systems for the rear rows of passenger cars requires an understanding of factors that contribute to injury causation and mitigation. When considering the rear row, of particular interest to the vehicle safety system designer should be injury to children, who are frequent occupants there. Development of pediatric vehicle safety systems is justified and should be guided by real world crash data. To set priorities for protecting specific age and restraint groups, safety system designers should use epidemiological data on the incidence and frequency of car crashes involving children. To set design specifications for safety systems requires an understanding of specific Injury Causation Scenarios (ICS’s), including a complete description of injuries received, the components within the vehicle that contribute to injury, and the biomechanics of the injury. Using such ICS studies, biomechanical experiments with post-mortem human subjects, animal surrogates and/or human volunteers can be conceived which are reflective of real world impact conditions and injury outcome, but conducted within a controlled laboratory environment with appropriate instrumentation. Such tests then form the basis for biofidelic anthropomorphic test devices and associated injury criteria and, coupled with an appropriate safety system test procedure, can potentially lead to enhanced safety systems. Seeking information on ICS’s, the safety system designer can turn to detailed in depth case reviews of convenience samples of real world crashes. For example, Howard et al. (2004) studied 19 children aged 0 to 12 years involved in side impacts in all types of restraint conditions and seating positions, who were admitted to one of two children’s hospitals in Canada. The authors found injuries occurred both with and without direct intrusion into the occupant compartment, suggesting that injuries may occur in center and farside seat positions, which are distant from struck side structures. As the Howard study attempted to describe injury causation across a wide range of restraint conditions, seating positions, and