Adherence and Perspiration While Wearing Lower Limb Prostheses

Study Overview
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Brief Summary
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Individuals with lower limb amputation often complain about uncomfortable residual limb skin temperatures and the accumulation of sweat inside their prostheses. It doesn't take long before the presence of sweat on the residual limb leads to a lack of confidence in the security of their prosthetic suspension. Some circumstances allow the wearer to doff the prosthesis before it falls off, wipe it and the residual limb dry, and then don it again. Another option is to simply reduce the intensity of activities before sweat becomes a problem. However, the Warfighter amputee may not be afforded such accommodations. For these service personnel, inadequate moisture management can significantly limit or inhibit their mobility. 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 sweating without compromising residual limb health and comfort. The aim of this research is to 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 sweating. The investigators also aim to compare how the three study prostheses effect residual limb skin health and comfort when participants pursue their usual activities in the home, work, and community environments. To achieve these aims, the investigators will to recruit 25 below-knee amputees. Each subject will be asked to be asked to wear: (1) their as-prescribed prosthesis, (2) a prosthesis with a perforated elastomeric liner that allows sweat to flow away from the skin, and (3) a prosthesis that has a battery and body-weight activated pump to flow air between the prosthesis and the residual limb skin, allowing expulsion of any accumulated sweat. Subjects will wear each of these prostheses in the home, work, and community environments for two weeks, after which the investigators will measure their residual limb health and comfort. Subjects will then walk on a treadmill in a room whose climate will be set to Middle East-like conditions: 35 °C (95 °F) and 50% relative humidity. After 30 minutes, the investigators will measure any slippage of their prosthesis relative to their limb and how much sweat is expelled. The investigators hypothesize there will be differences in the amount of slippage, residual limb health, and comfort between the three prostheses.

Detailed Description
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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. After wearing the prostheses in our environmental chamber set to Middle East-like conditions (35 °C and 50% relative humidity), the investigators hypothesize: H1.1 The amount of slippage (loss of adherence) will be different between the three suspension systems. H1.2 The amount of perspiration expelled will be different between the Uniprox and DAE-RED. After wearing the study prostheses in the home, work, and community environments for two weeks, the investigators hypothesize: H2.1 Residual limb skin hydration will be different between the three suspension systems. H2.2 Residual limb transepidermal water loss will be different between the three suspension systems. H2.3 The Socket Comfort Score will be different between the three suspension systems.

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

Conditions
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Lower Extremity Amputation

Intervention / Treatment
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* Device: Dynamic Air Exchange - Rising Edge Design (DAE-RED)
* Device: Perforated elastomeric liner
* Device: As-prescribed prosthesis


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Unilateral transtibial amputation Been fit with a prosthesis and used it for at least six months Wear the prosthesis for four or more ours on an average day Ambulate without upper extremity aids Able to walk for 30 minutes on a treadmill Exclusion Criteria: Improper fit and suspension with current prosthesis and one cannot be achieved with clinical resources (determined at initial visit) Current skin irritation or injury on residual limb Osteoarthritis, injury, or pain that interferes with walking ability Currently incarcerated Pregnant (determined via self-report) Inadequate cognitive function or language proficiency to consent to participate High (>20%) coronary heart disease risk at 10 years as determined by heir Framingham Risk Score

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 70 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Crossover Assignment
Interventional Model Description: This study will use a within-subject crossover design to identify differences in adherence (slippage), expulsion of perspiration, residual limb health, and comfort that may exist between the three study prostheses. The three study prostheses include: (1) a perforated elastomeric liner intended to transport perspiration away from the residual limb, (2) a dynamic air exchange - rising edge design (DAE-RED) suspension system expels perspiration to the prosthesis exterior using a hybrid battery-powered pump and a body-weight activated pump that expels perspiration into a distal chamber, and (3) the participant's as-prescribed prosthesis. The order in which participants wear the perforated elastomeric liner and the DAE-RED systems will be randomized (first or third), but the as-prescribed prosthesis will always be worn second.
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Environmental Chamber<br>All participants will wear all three study prostheses in an environmental chamber set at 35 degrees Celsius and 50% relative humidity. | Device: Dynamic Air Exchange - Rising Edge Design (DAE-RED)<br>* The DAE-RED suspension system expels perspiration to the prosthesis exterior using a hybrid battery-powered pump and a body-weight activated pump. To use the DAE-RED, subjects will be fit with a modified patellar tendon-bearing socket that fits over a custom liner and sock. Up to four air intake ports are located proximally on the liner, approximately 25 mm superior to the socket brim. These ports incorporate a microvalve that allows air to flow into the liner-skin interstitial space while still maintaining a vacuum suspension. Distally, the pin lock has a 3-mm hole along its longitudinal axis that allows perspiration to be expelled into a distal reservoir. The prosthesis will also include: a standard aluminum pylon, pyramid adapters, and an Ossur Proflex XC prosthetic foot with Unity pump and foot cover.<br>Device: Perforated elastomeric liner<br>* The unique element of this perforated elastomeric liner are small perforations ( 0.3 mm diameter), uniformly distributed on a 4 x 5 mm grid, but with no perforations on the distal umbrella, that allow perspiration to be exuded into the liner-socket interstitial space. To use the perforated elastomeric liner, subjects will be fit with a modified patellar tendon-bearing socket that fits over a sock and the perforated elastomeric liner with a pin lock. The sock, worn between the socket and the liner, is used to absorb perspiration that is transported through the perforations in the liner. When needed for residual limb volume control, additional socks will be donned and included in tare weighing. The prosthesis will also include: a standard aluminum pylon, pyramid adapters, and an Ossur Proflex XC prosthetic foot and cosmesis.<br>* Other names: Uniprox Softskin Air prosthesis liner;Device: As-prescribed prosthesis<br>* The individual's as-prescribed suspension system is the prosthesis prescription that the patient and their clinical care team believes is the best prosthesis for their needs.<br>|
| Experimental: Field Measurements<br>All participants will wear all three study prostheses in their home, work, and community environments for two weeks. | Device: Dynamic Air Exchange - Rising Edge Design (DAE-RED)<br>* The DAE-RED suspension system expels perspiration to the prosthesis exterior using a hybrid battery-powered pump and a body-weight activated pump. To use the DAE-RED, subjects will be fit with a modified patellar tendon-bearing socket that fits over a custom liner and sock. Up to four air intake ports are located proximally on the liner, approximately 25 mm superior to the socket brim. These ports incorporate a microvalve that allows air to flow into the liner-skin interstitial space while still maintaining a vacuum suspension. Distally, the pin lock has a 3-mm hole along its longitudinal axis that allows perspiration to be expelled into a distal reservoir. The prosthesis will also include: a standard aluminum pylon, pyramid adapters, and an Ossur Proflex XC prosthetic foot with Unity pump and foot cover.<br>Device: Perforated elastomeric liner<br>* The unique element of this perforated elastomeric liner are small perforations ( 0.3 mm diameter), uniformly distributed on a 4 x 5 mm grid, but with no perforations on the distal umbrella, that allow perspiration to be exuded into the liner-socket interstitial space. To use the perforated elastomeric liner, subjects will be fit with a modified patellar tendon-bearing socket that fits over a sock and the perforated elastomeric liner with a pin lock. The sock, worn between the socket and the liner, is used to absorb perspiration that is transported through the perforations in the liner. When needed for residual limb volume control, additional socks will be donned and included in tare weighing. The prosthesis will also include: a standard aluminum pylon, pyramid adapters, and an Ossur Proflex XC prosthetic foot and cosmesis.<br>* Other names: Uniprox Softskin Air prosthesis liner;Device: As-prescribed prosthesis<br>* The individual's as-prescribed suspension system is the prosthesis prescription that the patient and their clinical care team believes is the best prosthesis for their needs.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Adherence | The amount of slippage (loss of adherence) will be determined by measuring the distance between a mark on the skin and the proximal border of the liner. Adherence will be measured in millimeters. | After the 90-minute rest-walk-rest protocol where subjects enter our environmental chamber for a 30-minute seated acclimation and a 30-minute treadmill walk and then exit the chamber for a 30-minute seated rest. | 
| Expelled Perspiration | The amount of expelled perspiration will be determined by tare weight. Expelled perspiration will be measured in grams. | After the 90-minute rest-walk-rest protocol where subjects enter our environmental chamber for a 30-minute seated acclimation and a 30-minute treadmill walk and then exit the chamber for a 30-minute seated rest. | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Skin hydration | Skin hydration will be measured with a specialized instrument (Corneometer). A probe, acting as a capacitor, will apply an electric field to penetrate the skin (i.e., epidermis stratum corneum) on the posterior compartment of the residual limb to a depth of 10 to 20 μm. The amount of electrical charge stored by the capacitor is a function of skin hydration. Greater water content is proportional to higher capacitance, which is converted to converted to arbitrary units from 0 to 99. | After wearing the study prosthesis in the home, work, and community environments for two weeks | 
| Transepidermal water loss | Transepidermal water loss will be measured with a specialized instrument (Tewameter). A hollow cylinder probe with two pairs of sensors (temperature and relative humidity) will measure the density gradient of the water evaporation on the posterior compartment of the residual limb in units of g/m2/h. | After wearing the study prosthesis in the home, work, and community environments for two weeks | 
| Satisfaction with the prosthesis: 11-point Likert scale | An 11-point Likert scale will be used to record the subject's perception of satisfaction with the study prostheses. Participants will be asked to rate their satisfaction with the prosthesis on a 0 - 10 scale where 0 and 10 represent the least amount of satisfaction and the most amount of satisfaction imaginable, respectively. | After wearing the study prosthesis in the home, work, and community environments for two weeks | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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lower limb prosthesis, transtibial amputation, below knee amputation, adherence, perspiration