Efficacy of the WalkAide and AFOs for CVA

Stroke is the third leading cause of death in the United States and other developed countries and a major source of disability, often leading to hospitalization. Prognosis for regaining the ability to walk is good, with 64% of those initially dependent in walking regaining independence by three months. However, many gait abnormalities persist. Reduced hip, knee and ankle excursions during swing are among the persistent gait abnormalities contributing to poor or inefficient limb clearance. This is generally referred to as "foot drop", since the foot drops or drags along the ground during the swing phase. Swing phase abnormalities can result in decreased velocity, limited endurance and an increased risk for falls. These factors can limit mobility and independence in the community. Therefore, intervention is warranted. The conventional approach to address the poor swing limb function, specifically, insufficient ankle dorsiflexion, is the prescription of an ankle-foot orthosis (AFO). An AFO commonly limits ankle plantarflexion to enhance limb clearance during swing. An alternative approach is to stimulate the ankle dorsiflexors electrically during swing phase to reproduce motion, which can no longer be performed volitionally. The WalkAide is a new foot drop stimulator. This small, self-contained device attaches to the leg below the knee. The WalkAide contains a number of patented features, including a tilt sensor that measures the orientation of the leg with respect to the vertical. When the leg is tilted back at the end of stance, stimulation of the common peroneal nerve is initiated. This produces flexion of the ankle and other joints (if a flexion reflex is elicited) so that the leg can clear the ground during swing. When the leg is tilted forward at the end of swing phase, the stimulus is terminated. The electrodes attach to the inside of a cuff that is molded to the leg for reproducible positioning from day to day. The device is also designed so that all operations can be done with a single hand, since hemiparesis may prevent the subject from using the other hand. Because of its enhanced features, the WalkAide is anticipated to increase walking speed and improve the quality of life.