Abdominal injuries in belt-positioning booster seats.

Previous studies have demonstrated that booster seats reduce the risk of abdominal injuries by improving the fit of the seat belt on young children and encouraging better posture and compatibility with the vehicle seat. Recently, several studies have reported cases of abdominal injuries in booster seated children questioning the protective effects of these restraints. The objective of this study was to examine cases of abdominal injuries in booster seated children through parametric modeling to gain a thorough understanding of the injury causation scenarios. The Partners for Child Passenger Safety and CIREN in-depth crash investigation databases were queried to identify children in belt-positioning booster seats with abdominal injuries. The injury causation scenarios for these injuries were delineated using the CIREN Biotab method. The cases were modeled, using MADYMO with variations in key parameters, to determine the ranges of loads and loading rates for the abdomen and thorax. A parametric study was completed examining the influence of pretensioners and load limiters on the injury metrics obtained. Query of the two databases revealed three cases involving abdominal injuries to booster seated children. Children in two of the cases sustained a thoracic injury (AIS 3/AIS 4) in addition to their abdominal injuries (AIS 2) and review of these cases pointed to the role of shoulder belt loading in the injury causation. Modeling of these cases revealed chest compressions and accelerations of 30-53 mm and 41-89 g, respectively and abdominal deflection and velocity of 7.0-13.3 mm and 1.2-2.2 m/s, respectively. Parametric study suggested that coupling shoulder belt load limiting and lap belt buckle pretensioning resulted in improved chest and abdominal metrics while reducing head excursion, indicating that these technologies may provide injury reduction potential to pediatric rear seat occupants.