The numerical simulation by parameter optimization techniques has been proven to be a powerful tool in human walking dynamics research [1, 2]. Although there are several studies related to human walking dynamics, not much attention has been paid to the prediction of human gait assisted by robotic orthoses or exoskeletons. The aim of this work is to investigate the influence of some design parameters of an assistive orthosis on the injured subject’s gait dynamics by using a predictive parameter optimization approach.