Design and evaluation of a prototype gait orthosis for early rehabilitation of walking

Rehabilitation of walking should start early after injury to maximise the beneficial effects of gait restoration. Most current gait robotic systems are not suitable for patients who cannot maintain an upright position.  This study aimed to develop a prototype to test a supine-stepping system for early rehabilitation of walking.  Based on the pendulum model of walking, a supine-stepping system was designed through control of the toe and the ankle trajectories. This study implemented the pendulum concept of walking in a functional prototype including a bar-cam mechanism and a foot platform that makes it possible to perform stepping while lying in a supine position. The kinematics of supine stepping produced by the bar-cam prototype were firstly simulated by a corresponding bar-cam model in Matlab/Simmechanics, then investigated through a preliminary test using an empty leg frame, and lastly by tests on three able-bodied subjects. The experimental results from the bar-cam prototype were compared with the computer simulation results. Furthermore, supine stepping of one subject was compared with his performance during overground walking.  The lower extremity kinematics produced while performing stepping using the prototype matched the corresponding simulation results as well as the performance during overground walking.  This study demonstrated the technical feasibility of implementing the pendulum concept in a gait orthosis for early rehabilitation of walking.