The magnitude and the type of lower leg injuries observed in real-world frontal accidents as well as the injury mechanisms in this body region have been examined. An investigation into the APR (Association Peugeot Renault) accident database has been carried out. From 2,022 front-seat occupants, restrained or not, involved in a frontal collision, 208 sustained either a strain, a laceration into joint, a dislocation or a fracture below the tibial plateaux. An in-depth analysis of the injury mechanisms has been performed using the X-rays of 42 occupants.

The most prominent injuries are metatarsal fractures (39 cases), malleolar fractures (39 cases) and ankle sprains (44 cases).

The brake pedal increases significantly the number of injuries on the right foot of the drivers. However no differences have been found between the right and the left legs as far as drivers’ ankles are concerned. Passengers sustain more injuries on their left ankle, and seem to have more injuries on their right foot, directly exposed to wheel well intrusions.

The most significant parameters which influence the lower leg injuries appear to be the delta-v correlated with the footwell intrusion and the configuration of the impact especially the overlap. The seat-belt use and the occupant’s age do not affect significantly lower leg injuries.

Two main mechanisms are identified. In the first one, forces acting under the metatarsal condyles coupled with the inertial effect of a dorsiflexing foot produce metatarsal fractures. Malleolar fractures and ankle sprains are attributed to eversion/inversion motions caused by forces acting under the ball of the foot. This study represents a basis for tests involving cadavers and the Hybrid III dummy.