Biomechanics of Ankle and Hindfoot Injuries in Dynamic Axial Loading

Twenty-three Post Mortem Human Surrogate (PMHS) limbs were impacted using a test set up that was developed to simulate the loading conditions seen in a frontal collision. Articulation studies were performed on each limb prior to impact.

Failure occurred at impact loads of 5.7+/-1.9 kN (resultant tibial failure load 6.4+/-1.9 kN) and the following injuries were generated: 9 intra-articular calcaneal fractures; 1 talar neck and 2 talar body fracture; 3 intra-articular distal tibial (pilon) fractures; 2 malleolar fractures; 3 soft tissue injuries and 3 had no detectable injury.

The impact test conditions were replicated with a Hybrid III leg in a first attempt at developing injury risk functions for the dummy.

This study has demonstrated the significance of pre-load through muscle tension and the intrinsic properties of PMHS specimens in the generation of severe ankle and hindfoot injury.