Changes in foot loading following plantar fasciotomy: a computer modeling study.

Forward dynamic simulations of a toe-rise task were developed to explore the outcomes of plantar fasciotomy, a surgery commonly performed to relieve heel pain. The specific objectives of this study were to develop such a simulation, validate its predictions, and simulate rising on toes using a model from which the plantar fascia had been removed. Root-mean squared differences between the intact model and measurements of healthy subjects were found to be 0.009 body weights (BW) and 0.055 BW for the horizontal and vertical ground reaction forces and 7.1 mm, 11.3 mm, and 0.48 deg for the horizontal, vertical and rotational positions of the pelvis. Simulated plantar fasciotomy increased passive arch torques by 7.4%, increased metatarsal head contact forces by 18%, and resulted in greater toe flexor activity. These simulations may explain the mechanisms behind plantar fasciotomy complications when patients perform activities that require loading of the plantarflexors and the longitudinal arch.