An in-depth analysis of 200 Abbreviated Injury Score (AIS) 2+ injuries to the lower extremity in frontal collisions has been performed using impairment scales devised by the American Orthopaedic Foot and Ankle Society.

The most important subgroup of injuries were identified as ankle/hindfoot injuries. There were 63 such injuries sustained by 53 occupants and these were analyzed in greater depth.

Inversion or eversion was identified as the mechanism of injury for 40 % of injuries. However in 70% of these fractures caused by inversion or eversion, minimal or no long term impairment would be expected Injuries associated with significant long-term impairment were attributed to axial forces (i.e. loads perpendicular to the foot).

Combined vehicle/injury analysis demonstrated a strong association between toe-pan intrusion and these injuries. Interaction between the occupant and the pedals was identified as a probable injury source in only 25% of injuries to the ankle and hindfoot.

The results of this study are being used to plan a program of biomechanical research to establish injury risk functions for the ankle and hindfoot.