Integration of a semi-active variable-stiffness lower-limb prosthesis into a musculoskeletal model

This abstract presents methodology for modeling the energy storage and return properties of a semi-active variable-stiffness lower-limb prosthesis in the OpenSim musculoskeletal modeling platform. The prosthesis was modeled as a rigid hindfoot with an elastically hinged forefoot; stiffness was varied by changing the location of this hinge. Effective forefoot stiffness in the model was estimated by simulating deflection under a point load. Simulations reproduced experimental data for stiffness (R^2 = 0.99) and displacement under a matched load (R^2 > 0.99). This modeling approach is deemed satisfactory to capture the effects of variable stiffness in a dynamic gait model.