Effect of Walking Speed on Angular Stiffness and Roll-Over Shape of the Intact and Prosthetic Feet of Transtibial Amputees

The calculated roll-over shape and respective radius of intact and prosthetic feet has been shown to be a useful measure of lower limb function during walking [1–2]. Hansen et al [3] reported that the roll-over radius, R, is constant over a range of speeds for the intact foot-ankle system. It may be assumed that the prosthetic foot R would also be constant with increased walking speed. Similarly, the angular stiffness of prosthetic feet is not likely to change with walking speed, as the material stiffness remains unchanged. However, the effective angular stiffness of the intact ankle may increase with the plantar flexor moment during the stance phase of gait, which typically increases in magnitude with walking speed.