Assist-as-Needed Robot-Aided Gait Training Improves Walking Function in Individuals Following Stroke

Abstract

A novel robot-aided assist-as-needed gait training paradigm has been developed recently. This paradigm encourages subjects' active participation during training. Previous pilot studies demonstrated that assist-as-needed robot-aided gait training (RAGT) improves treadmill walking performance post-stroke. However, it is not known if there is an over-ground transfer of the training effects from RAGT on treadmill or long-term retention of the effects. The purpose of the current study was to examine the effects of assist-as-needed RAGT on over-ground walking pattern post-stroke. Nine stroke subjects received RAGT with visual feedback of each subject's instantaneous ankle malleolus position relative to a target template for 15 40-minute sessions. Clinical evaluations and gait analyses were performed before, immediately after, and 6 months post-training. Stroke subjects demonstrated significant improvements and some long-term retention of the improvements in their self-selected over-ground walking speed, Dynamic Gait Index, Timed Up and Go, peak knee flexion angle during swing phase and total hip joint excursion over the whole gait cycle for their affected leg . These preliminary results demonstrate that subjects improved their over-ground walking pattern and some clinical gait measures post-training suggesting that assist-as-needed RAGT including visual feedback may be an effective approach to improve over-ground walking pattern post-stroke.

Fig. 1.

The active leg exoskeleton (ALEX) worn by the subjects on their affected extremity during training and treadmill evaluation.

Fig. 2.

Target template based on ankle malleolus and application of the compliant force field. The dashed line represents the target template based on the malleolus path and the black solid lines represent the walls of the virtual tunnel on either sides of the template. The solid black dot represents instantaneous malleolus position of the subject with the normal (Fn) and tangential (Ft) forces represented by the solid black arrows moving the subject’s ankle closer to the template.

Fig. 3.

Clinical outcome measures and maximum foot clearance averaged across subjects at baseline, after training (post-training), and 6 months after training (follow-up). Error bars represent the standard deviation across subjects. * p<0.017

Fig. 4.

Peak hip and knee flexion angles and peak ankle dorsiflexion angle (degrees) during the swing phase and total hip, knee, and ankle joint excursion (degrees) during the gait cycle averaged across subjects for the paretic leg. Error bars represent the standard deviation across subjects. * p<0.017

Fig. 5.

Each subject’s area between the ankle malleolus path at their self-selected walking speed and the target template averaged across swing phase. Error bars represent standard deviation across gait cycles.