Effects of Temperature Control Liner Materials on Long-Term Outcomes of Prosthesis Use
Abstract
A problem in fitting people with lower limb loss with artificial legs is keeping the residual (amputated) limb in a prosthesis socket. Unlike the other prosthetic components, such as the foot or knee joint, sockets are individually fabricated for each patient. Such a socket is the most important part of an artificial leg as it must be designed to support the user’s body weight during standing and walking. It also must provide a sufficient suspension to prevent the artificial leg from slipping off the limb when lifted. Both of those objectives require that the contact area between the socket and the residual limb skin be as large as possible. The current standard method of accomplishing that is the use of flexible liners that are being worn directly between the skin and the rigid wall of the actual socket. The soft material of the liner -- usually silicone or polyurethane gel -- helps distribute contact forces more evenly, and because the liner material sticks to the skin and covers the entire residual, suspension is also improved. One common side effect of using liners is excessive sweating of the residual limb. This is thought to be due to the lack of air circulation, which traps moisture and heat inside the liner. Apart from being uncomfortable to the user, this sweating can also lead to serious problems. Sweaty skin loses the tight contact with the liner. It then starts rubbing against the material with every step. After a while, this can damage the skin and lead to pain and infection risk. When such damage occurs, patients are usually advised to not use the prosthesis until the skin has healed again. Not being able to walk for several days at a time can be very disruptive to peoples’ regular lives, particularly if their line of work or their leisure activities are not compatible with wheelchair use. Recently, a new generation of prosthesis liners has become available that promises a mechanism of temperature control to avoid those undesirable side effects. These liners are infused with phase-change material, a material that “melts” from a solid phase into a liquid phase at a temperature slightly above regular skin temperature. Much like the evaporation of sweat, this “melting” also has a cooling effect on the skin. Studies have shown that the measured increase in skin temperature when using these liners is clearly lower than in conventional liners. The currently proposed study will investigate whether those differences lead to any tangible benefits for the user. For instance, it will be compared for how many days in a year users of either liner will be unable to use their prosthesis. For that purpose, participants will be asked to wear a conventional liner and a phase-change material liner for 6 months each. Those periods will be timed so that an even amount of cold and warm seasons is covered in each trial. On top of recording days of prosthesis use, step counts and walking speed will be measured. Participants will also be asked to fill in standardized questionnaires to evaluate their artificial limb. The risk of participating in this study is considered to be low, as all of the used interventions are tried and tested, approved, and commercially available medical products. The usual safeguards will be applied to protect the confidentiality of collected sensitive information. Results are expected in year 2 of the study. There are approximately 2 million people living with limb loss in the United States. Military service increases the risk of severe injury, and thereby the risk of limb loss substantially. The number of Service members who experienced combat-related major limb loss only in the recent conflicts since 2003 exceeds 1,600. Including Veterans from prior wars, there are approximately 40,000 individuals with limb loss who are served by the Veterans Affairs Prosthetics and Sensory Aids Service. Improving the comfort and functionality of their artificial limbs will help them keep
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Oct 29, 2018
- Source ID
- W81XWH1710700
Entities
People
- Goeran Fiedler
Organizations
- United States Army
- University of Pittsburgh