In this study, a dynamic multibody model of the 50th percentile male lower extremity is developed to examine internal loading during plantar impact. The foot and leg, represented by five and seven rigid bodies respectively, are provided with degrees of freedom and stiffness values from cadaveric and volunteer data. Soft tissue structures, including the heel pad, ankle ligaments, and triceps surae muscles are represented with nonlinear viscoelastic elements. Validation involved subjecting the model to two different plantar impact scenarios, and comparing the time histories of tibia compression, Achilles tendon tension, and ankle motion with those from the cadaveric test data. Injuries are predicted in the model by comparing force within the model elements with experimentally determined and published failure criteria for the respective structures. This model provides a tool for predicting soft tissue and hard tissue lower extremity injuries associated with a variety of foot and ankle loading environments. (A)
Abstract