Novel Lower-Limb Prostheses: Comparing Adherence, Perspiration, and Residual Limb Skin Health in a Hot, Humid Environment and During Activities of Daily Living

Individuals with lower limb amputation often complain about uncomfortable residual limb skin temperatures, accumulation of perspiration inside their prostheses, and loss of confidence in suspension security that often leads them to cease their activities or, in demanding circumstances, may lead to their prosthesis falling off. Most amputees can sense the impending loss of suspension during vigorous activities and can stop, doff the prosthesis, wipe it and the residual limb dry, and then don it again. However, the Warfighter amputee may not be afforded such accommodations.

The investigators will compare the performance of an individual's as-prescribed suspension with two exciting alternatives: a new-to-market liner intended to transport perspiration away from the skin and an improved version of the Dynamic Air Exchange (DAE) suspension system the investigators developed. The new-to-market suspension system consists of a perforated elastomeric liner that allows perspiration to be exuded into the liner-prosthesis space. Anecdotal reports suggest this liner (Uniprox's SoftSkin Air), can maintain suspension during profuse perspiration, but may result in excessive skin dryness and discomfort. The improved Dynamic Air Exchange - Rising Edge Design (DAE-RED) suspension expels accumulated perspiration using a vacuum pump like its predecessor, but incorporates hybrid, body-weight activated pump to minimize battery consumption and a revised ventilation system obviating the need for undesirable exterior tube connections.

The objective of the proposed research is to provide lower limb amputees who work in demanding environments with a prosthesis that remains secure despite profuse residual limb perspiration without compromising residual limb health and comfort.

The proposed research has two specific aims: (1) compare three different, lower limb prosthetic suspension systems and identify which is most effective at maintaining a secure adherence when worn in conditions that result in profuse perspiration, and (2) compare how the three suspension systems effect residual limb skin health and comfort when participants pursue their usual activities in the home, work, and community environments.

The investigators will recruit unilateral transtibial amputees who are successful ambulators on their as-prescribed prosthesis and collect baseline data (residual limb skin hydration, transepidermal water loss (skin barrier function), and Socket Comfort Score). After fitting the participants with Uniprox and DAE-RED prostheses, subjects will wear one of these study prostheses (random order) for two weeks, after which the investigators will measure their skin hydration, transepidermal water loss, and Socket Comfort Score. The subject will then enter our environmental chamber (35° C and 50% relative humidity) and sit for a 30-minute acclimation period. The subject will then walk for 30 minutes on a treadmill at their self-selected speed. Subjects will then exit the environmental chamber and sit for 30 minutes in a comfortable climate (~20° C and 50% relative humidity). The amount of slippage, along with the perspiration accumulated/expelled, will be then be measured. Subjects will then be fit with their as-prescribed prosthesis and the protocol repeated to washout intervention effects. Finally, subjects will be fit with the other study prosthesis (either Uniprox or DAE-RED) and repeat the protocol.