Yes, you can use OpenSIM for forward simulation but you will have to customize the model with your foot orthosis . You will need gait data of healthy individuals without wearing orthosis for Biomechanics, to compare with simulation results. Refer https://fenix.tecnico.ulisboa.pt/dow...9009/Final.pdf , http://www.umass.edu/locomotion/pdfs/embs-2014.pdf .