Many accident studies have shown that lower leg injuries are common in frontal impact car accidents. Of these, injuries to the ankle are the most serious and the most likely to lead to long-term morbidity.

Fourteen PMHS specimens were impacted using a new double-impact sled rig that loads the leg in a realistic, car-equivalent manner. The sled separately reproduces the vehicle deceleration and footwell intrusion typically seen in frontal impacts.

The impacts were at a range of foot loading severities, with a constant-force knee restraint and Achilles tendon tension applied such as to reproduce the emergency braking forces found in simulator studies. Only one impact was applied to each specimen, which was then examined for injury by x-ray and necropsy.

The injuries generated were considered to be representative of those seen in car accidents. Tests at each severity were then replicated with a THORLx lower leg and an injury risk curve for the THOR-Lx is presented.