Acquiring of muscle forces of a normal foot during miscellaneous postures of gait

The purpose of this paper is presenting a multi-segment static model of the foot, in order to find muscle forces of the leg and foot in miscellaneous posture of gait. To obtain an exact knowledge about magnitude and location of forces in various parts of the foot, a more precise foot model is needed. In the present study, a four segment musculoskeletal model of foot (hallux, forefoot and hindfoot plus one segment for tibia) is used to assess the foot during gait. Input parameters of the model are relative angles between different segments of the model and ground reaction forces on the first metatarsal and heel. Then, the main muscles are added to the model, and Newton equations of equilibrium are applied to study the inverse dynamic of the problem. Since several muscles act in foot motion, the number of unknown parameters in the equations is greater than the number of known ones. Therefore, with the aim of optimizing Euclidean norm of muscle forces, an optimal solution for the problem is found.