New Approach to Heat, Sweat, and Moisture Management
The Underlay is a thin textile sleeve worn directly against the residual limb, underneath the prosthetic liner. It is designed to transport moisture away from the skin, support evaporation, reduce odor, and help maintain a cooler, drier skin environment throughout the day.
Its knitted structure draws sweat toward a breathable mesh section that extends beyond the proximal edge of the liner. This exposed area allows moisture and heat to move outside the sealed socket environment, where evaporation can occur more effectively.
The textile also incorporates two Polygiene technologies:
StayFresh® is a silver chloride-based antimicrobial treatment that helps inhibit odor-causing bacteria and keeps the product fresher between uses.
StayCool® is a moisture-activated polymer technology designed to lower the fabric temperature by approximately 2-3°C when activated by sweat.
Together, these components address moisture, heat, and odor directly at the skin-liner interface.
Open and Closed Versions
The Underlay TT is available in open and closed configurations.
The open version leaves the distal end of the residual limb exposed, maintaining direct contact between the skin and liner. When positioned correctly, it preserves suspension while allowing the upper section of the textile to extend beyond the liner for airflow and evaporation.
The closed version provides full distal coverage and may be preferred for patients with bulbous limb shapes or when clinicians want to avoid an open distal edge.
Both versions add minimal thickness. With a textile layer of approximately 0.5 mm, the Underlay can be integrated into an existing prosthetic setup without meaningful changes to socket fit or alignment.
Broad Compatibility
The Underlay is designed for use with common liner materials, including silicone, TPE, TPU, seal-in, and vacuum-compatible liners.
Depending on the selected model and patient configuration, it can also be used with major suspension systems, including:
- Pin-lock systems
- Lanyard systems
- Suspension sleeves
- Seal-in systems
- Active and passive vacuum systems
No socket modification is required, and the patient’s usual donning routine remains largely unchanged.
Clinical and User Findings
The Underlay was evaluated with 15 lower-limb prosthesis users during daily wear and activities including walking, cycling, hockey, treadmill exercise, and wheelchair rugby.
Users reported:
- A 51 percent reduction in perceived humidity
- A 38 percent reduction in perceived heat
- An average comfort score of 8 out of 10
In a controlled evaluation using sensors placed beneath the liner, the Underlay reduced measured relative humidity by 17 percent. Humidity also increased more slowly during both rest and walking, indicating that the product begins managing moisture before high-intensity activity begins.
Users who had previously tried traditional sweat socks generally described the Underlay as lighter, lower profile, and more effective at limiting moisture buildup. Some also reported needing to remove their prosthesis less frequently during the day to dry the limb.
Supporting Skin Comfort and Suspension
Persistent moisture can soften the skin, increase friction and shear, contribute to irritation, and create slippage between the limb and liner. By helping keep the interface drier, the Underlay is designed to support skin comfort and reduce moisture-related movement inside the socket.
Bench testing also evaluated whether the additional textile layer affected suspension. Results showed retention forces above the benchmark associated with demanding activities such as running when the product was positioned according to the recommended instructions.
Simple Integration Into Practice
The Underlay requires no socket modification, adds only a few seconds to the normal donning process, and is available in multiple sizes and lengths.
It provides clinicians with a practical new option for patients experiencing excessive sweating, heat buildup, odor, skin discomfort, repeated mid-day doffing, or moisture-related suspension challenges.
Contact Ethnocare today at clinics@ethnocare.ca to learn more about the Underlay and how it can be integrated into your clinical practice.
