Real-time monitoring of internal deformations in the soft tissues of the foot: a new approach in gait analysis

No technology is presently available to provide information on internal deformations and stresses in plantar soft tissues during evaluation of the gait pattern, in real-time. Because internal deformations and stresses in the plantar pad are critical factors in foot injuries, this severely limits evaluation of patients. To allow such analyses, we developed a hierarchical modeling system integrating structural and finite element (FE) foot models. The higher-order part is a two-dimensional model that provides analytical solution of the time-dependent plantar fascia tensile forces during the stance phase. These forces are transferred, together with measured ground reactions to the lower-order level of the modeling system, where they serve as boundary conditions for local FE analysis of deformations and stresses in the plantar pad. Boundary conditions from the higher-order model were validated with respect to previous, more detailed FE models that could not be utilized for real-time analysis. Subsequently, real-time deformations and stresses in the plantar pad were obtained during gait.