Evaluation of energy-absorbing materials as a means to reduce foot/ankle axial load injury risk

Abstract

Current restraint systems, such as seatbelts and airbags, have been developed mostly to protect the head and thorax during frontal crashes. They do not necessarily have equivalent effciency for lower extremities because of other loading factors such as the interaction between the foot and toepan or pedals. A relatively high frequency of foot and ankle injuries in combination with high morbidity warrants research into injury countermeasures. An energy-absorbing aluminium honeycomb was investigated as a means of load reduction during a simulated frontal impact with toepan intrusion. Test surrogates included human cadavers, a 50th percentile male Hybrid III leg with 45° dorsiflexion ankle and soft joint stop and a 50th percentile male Thor-Lx/HIIIr. Inclusion of an energy absorber between the cadaver heel and intruding footplate reduced tibia axial loads by as much as 39 per cent compared to cases without an energy absorber. Dummy results were compared to the human response and the Thor-Lx appeared to be more biofidelic than the Hybrid III.