Inverse dynamics of the lower extremities: novel approach considering talocrural and subtalar joint axis

A recent survey of epidemiological studies lists ankle injuries as one common sport injury. However, the details of the injury mechanisms of ankle sprains — the majority of ankle injuries — remain not well understood. The purpose of the presented study is twofold. The first aim is to introduce a new, widely applicable method to calculate ankle joint torques during movement using inverse dynamics. The subtalar and talocrural joint are modeled as anatomically based revolute joints. The kinematics of the lower extremities and ground reaction force are used as input data. Second, a comparison of two calculation approaches (dynamic versus static) is reported, aimed at verifying and simplifying the introduced method to have a more convenient tool at hand for applications in the field. For one first movement measurement (hopping), the calculated joint torques show a good match for the two calculation approaches. After further application, the evaluation of the resulting joint torques will provide further insights into the joint mechanics and can contribute to a better understanding of the respective injury mechanisms. Hence, this approach is interesting for researchers to be used in order to understand ankle injuries and to determine the influence of landing grounds and shoes on ankle joint torques.