Peripheral neuropathy (PN), commonly caused by diabetes mellitus, is a debilitating condition that currently affects approximately 20 million Americans. Chronic symptoms of PN often involve pain and weakness of the lower limbs, with eventual sensation loss on the plantar surfaces of the feet. According to epidemiological studies, reduced foot sole sensation has been linked to decreased standing stability [1] and an increased risk of falling [2]. Consequently, cost-effective interventions are needed to improve balance and mobility in this population.
A growing body of research suggests that vibrotactile cues delivered to sensate areas of the lower limb may be an effective way to provide information about foot sole pressure to PN patients who experience poor balance control. Indeed, sensory substitution devices that provide vibrotactile feedback have been shown to aid in balance and improve postural control in various patient populations [3–7]. However, none of these technologies have been based on measurements of foot pressure nor have they been used as a balance prosthesis.
The goal of this study was to investigate the effect of a new external lower-limb sensory prosthesis, the Walkasins™, on the balance and gait of individuals with PN who experience balance problems [8]. Walkasins™ consist of two parts: a leg unit and a foot pad (Figure 1). The leg unit wraps around the lower leg of the user and contains electronics for reading foot pad pressure signals, a microprocessor, and four vibrating motors that provide gentle tactile sensory cues to the front, back, medial, and lateral surfaces of the user’s leg. These cues reflect real-time foot pressure information at a location above the ankle where skin sensation is still present. The leg unit has a power button, two status LEDs, and a reset button (not shown in Figure 1). Power is supplied by a rechargeable internal battery. The foot pad is a thin consumable sole insert that can be cut to size and fit into a regular shoe. The foot pad connects to the leg unit through a physical cable. In this study, subjects performed gait and balance assessments with and without the Walkasins™ turned on in order to determine its short-term effects.
