Injuries to the lower extremities continue to occur in frontal crashes despite increased attention on vehicle structure and restraint design. Since lower extremity injuries can lead to costly rehabilitation and longterm disability, it is important to understand their causation and how well modern design practices are affecting their incidence and severity. This study investigates lower limb injury risk and causation in a U.S. crash database, and compares the risk and severity based on the nature of the crash and vehicle specifications. This study uses weighted NASS-CDS data to give an overall view of lower limb injury risk over a period from 1994 until 2007. Crashes will be categorized by intrusion level, delta-V, and vehicle model year. Particular interest will be paid to leg, foot and ankle injuries as well as occupant factors and intrusion levels.

A review of the representative data suggests that foot and ankle injury prevalence has not decreased in newer model-year vehicles, and that injury risk to the foot and ankle has actually increased despite structural improvements aimed at reducing footwell deformation. When broken down by delta-V, the trends vary, but the majority of the injuries occur at lower crash severities. Although vehicle structures and restraints have been optimized for improved performance in consumer information and regulatory tests, the risk of sustaining lower extremity injuries, especially to the foot and ankle, remains an issue that deserves further attention.