Improved models for the lower leg in paraplegics

When the lower leg of a paraplegic subject is extended and released, it undergoes a damped oscillation (pendulum test), but the oscillation deviates from that expected for a linear system. Also, the response to a slow, repetitive extension and flexion (pull test) shows deviations from that expected from the gravitational torque, including considerable hysteresis. In contrast to more complex models previously used, adequate fits were obtained From a linear second order model to which a term representing coulombic damping