Load-Leg Support as a Biomechanical Intervention in Rear-Facing Child Restraint Misuse

In this project, we evaluated the biomechanical effectiveness of antirotation load-leg support in rear-facing child restraint systems (CRSs) under both proper and common misuse installation conditions. Dynamic FMVSS 213 sled tests were conducted using a CRABI 12-month anthropomorphic test device under four configurations—proper installation, loose seat, loose harness, and combined loose seat and harness—with and without load-leg support. The load leg provided an additional load-transfer pathway from the CRS to the vehicle floor, reducing forward CRS rotation as well as head and neck injury metrics across all tested conditions, although its protective effect was diminished when harness slack reduced child–restraint coupling. These findings provide insight into the biomechanical mechanisms of load-leg support and can inform the development of more misuse-resistant child restraint systems and improved strategies for pediatric occupant protection in frontal crashes.