Modeling neuromuscular effects of ankle foot orthoses (AFOs) in computer simulations of gait.

Ankle foot orthoses (AFOs) provide immediate changes to gait kinematics and alter EMG-recorded muscle activity during gait; yet our understanding of neuromuscular adaptations while using AFOs remains incomplete. To address this, we have developed a tunable AFO model to predict torque from ankle angle and velocity and to identify plausible changes in muscle excitation and function in a walking simulation. Using a dynamometer in passive mode, we isolated flexion/extension torque of three polypropylene spring leaf AFOs at 5 degrees/s, 30 degrees/s and 120 degrees/s, from which a model of AFO torque as a function of deformation angle, velocity and size was derived with predictive ability of R2>0.