A predictive simulation study on how ankle foot orthosis stiffness affects the sit-to-walk movement

Ankle-foot orthoses (AFOs) can improve walking mobility in individuals with calf muscle weakness, but their impact on sit-to-walk, a common daily activity, is underexplored. Using predictive simulations, we tested the effects of AFO stiffness on sit-to-walk in case of different degrees of plantarflexor weakness. Results showed that AFO stiffness significantly affects sit-to-walk kinematics and kinetics, with an optimal stiffness for minimizing effort. This optimum stiffness depends on severity of weakness and seat height. These findings emphasize the need to assess and consider the effects of AFO stiffness in daily life activities besides walking.