It’s summertime now and there are lots of opportunities to get outside and be active. However, a common complaint with prosthetic users is the sweat buildup inside the socket, especially when a gel liner is used. Gel liners were developed in the 1980’s, and are great for absorbing shear forces and aiding in suspension. Unfortunately, they are also akin to wearing a wetsuit against your skin which is especially uncomfortable in hot and humid conditions.
Does everyone struggle with sweat and temperature conditions?
In my experience, some people struggle with managing sweat more than others, but almost every patient I talk to complains that it is noticeable. The consequences range from enduring through mild discomfort to having to take off the prosthesis and wipe off excess sweat throughout the day. Of course, activity plays a role in sweat production. The most problematic sweat production occurs on the residual limb the same time the rest of the body is also producing noticeable sweat. For new amputees, there is an acclimation process when starting to wear a gel liner. They may experience noticeable sweat of their residual limb even when the rest of their body is not sweating, such as when walking around. After a few months, however, the body starts to recognize that the skin in contact with the gel does not need to sweat as much and most prosthetic users notice a decrease in the amount of sweat produced. Even so, it doesn’t shut things off completely and sweat continues to be an issue for most prosthetic user.
Why is sweat inside the prosthesis a problem?
In addition to being uncomfortable, sweat inside the gel liner can cause the liner to slip off the skin. When this happens, it affects suspension, causes the socket to fit differently, and increases movement of the residual limb in relation to the socket. The sweat makes the skin softer and more prone to blister formation or skin maceration. Usually, while participating in sports or while exercising, it’s the most inconvenient time to take off the prosthesis and wipe off the sweat, but ignoring it often leads to unfortunate skin problems.
What can you do about it?
The answer is to be prepared. Bring a wash cloth and socks with you and anticipate breaks in workouts or activities to take off your prosthesis to wipe off sweat and change sock ply if needed. Make sure your gel liner is in good shape and fitting well. A loose fitting liner allows sweat to pool more than a properly fitting liner. Underarm antiperspirant can also help with sweat on the residual limb. This should be applied at night when the prosthesis is not being worn rather than in the morning since the chemicals can deteriorate some gel liner materials. Antiperspirants such as Certain Dri, which is prescription-strength but does not require an actual prescription, can be even more powerful, but should be started every other day since these products carry the risk of drying out the skin. Some of the sweat from the body can make its way down the body into the gel liner. For below the knee amputation levels, a head sweat band worn above the suspension sleeve or gel liner can help to absorb body sweat. Recently, wicking socks such as Swiftwick Valor socks and Knit Rite liner liners have become available for use under the liner. I have seen mixed results with such products. A new product from Willowwood called the smart temp liner contains outlast, a material that NASA developed for astronauts, and their internal studies have recorded lower skin temperatures and less sweat production in comparison to traditional materials.
What research is being done to develop better interventions for the future?
As it turns out, essentially adding the components of a refrigerator to a prosthesis is pretty complicated when factoring in bulk, noise, weight, and required customization. A group out of San Antonio was recently awarded a grant to develop this concept. You can read more about it at http://www.npr.org/2014/11/11/363313691/vets-self-cooling-prosthetic-could-help-amputees-beat-the-heat.
A promising intervention using botox has been used to treat underarm and palm hyperhidrosis (excessive sweating) for years. During my experience at Walter Reed, this treatment was being tried for residual limb hyperhidrosis as well and was very effective. A recently published study reports a 50% reduction in sweat just four weeks after the injection. This study also revealed no change in residual limb and phantom limb pain with botox injection. You can learn more about that study at http://www.archives-pmr.org/article/S0003-9993(16)00034-4/abstract.
In summary, sweat inside a prosthesis is not only uncomfortable, it can also lead to skin breakdown. Treatment options include: taking breaks to wipe off sweat, use of antiperspirants, choice of properly fit gel liner material and socks against the skin, and botox injection. No one treatment is completely effective, so combining treatments is currently the best option.
By Zach Harvey, CPO