Can Temperature-Regulating Liners Improve Lower-Limb Prosthesis Outcomes?

Reading Time: 5 minutes

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Summary:

• Study explores if temperature-regulating liners improve prosthesis comfort

• Phase-change materials used to reduce limb heat, sweat, and skin irritation

• Long-term trial shows improved gait symmetry in some users

• No major functional gains, but comfort trends are promising

• Experts call for larger studies to confirm long-term benefits

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For many people with lower-limb loss, thermal discomfort inside the prosthetic socket is a persistent challenge that can affect comfort, skin health, mobility, and overall quality of life. Traditional prosthetic liners, typically made of silicone or gel, insulate the residual limb and can trap heat and moisture. This buildup often leads to excessive sweating, irritation, friction injuries, and compromised prosthesis use, particularly during warm weather or physical activity. Addressing this microclimate at the skin-socket interface has become a priority in modern prosthetic research and design.

A promising innovation in this space is the adoption of temperature-regulating prosthetic liners—liners enhanced with phase-change materials (PCMs) or other thermal management technologies to stabilize limb temperature. But can these liners truly improve the experience for lower-limb prosthesis users? Recent research on the long-term use of PCMs sheds light on this question.

Phase-Change Materials (PCMs): How They Work  

PCMs are materials that absorb or release heat as they change between solid and liquid at specific temperatures. When used in prosthetic liners, they serve as thermal buffers by absorbing excess heat during activity and releasing it gradually as temperatures fall, helping to stabilize skin-liner temperature fluctuations. Pilot studies have shown that PCM-enhanced liners reduce temperature increases and perspiration during short-term tests compared to traditional liners.

In a 2015 study, 16 participants wore WillowWood SmartTemp liners and a placebo liner while riding a stationary bike for 25 minutes. The study measured residual limb temperature and sweat within the liner afterward. Results indicated that PCM liners kept socket temperature and perspiration lower and slower to rise than conventional gel liners. However, as a short, lab-based study, its clinical relevance is limited.

This recent study on the long-term use of PCMs aimed to better understand both the short-term and long-term benefits of PCM liners versus conventional liners.

The Study: Long-Term Effects of PCM Liners  

Researchers carried out a year-long, double-blinded crossover study to compare PCM liners with traditional gel liners in below-knee amputees. Fourteen participants switched between the two liner types every six months. The study focused on three main areas:

• Prosthesis use: How much and how often the prosthesis was used.

• Physical performance: Evaluated through step counts and 2-minute walking tests.

• Gait symmetry: Assessed by pressure and force distribution during walking.

Activity tracking was done with StepWatch pedometers, physical performance was tested using a 2-minute walk test, and gait symmetry was analyzed with TekScan F-Scan sensors.

The Findings  

Results indicated a trend toward better gait symmetry and comfort with PCM liners, although no statistically significant differences were observed between PCM and conventional liners in step counts, walking distance, or gait parameters.

While average daily step counts and 2-minute walk test distances did not show significant improvements with PCM liners, some individuals demonstrated higher activity levels and step counts when using PCM liners. Furthermore, gait analysis using F-Scan technology revealed notable differences in foot pressure distribution among certain participants, with PCM liners generally linked to improved symmetry in ground reaction force, stride time, and foot pressure.

Additionally, previous short-term studies suggested that PCM liners reduce residual limb temperature and sweating, but this longer-term trial did not find significant functional benefits.

Interpreting the Findings  

At first glance, the lack of statistically significant results might seem disappointing. However, several key insights emerge:

• Practicality and User Acceptance: PCM liners were worn successfully for extended periods without significant side effects, showing that temperature-regulating technology is practical for everyday use.

• Positive Trends in Thermal Regulation: Although not statistically significant, consistent patterns across various outcomes (such as usage, physical performance, and gait metrics) hint at potential benefits that warrant further investigation in larger studies.

• Clinical vs.Statistical Significance: Prosthesis users might experience small but meaningful improvements in comfort or performance in daily life, which may not be fully reflected in statistical analysis. User-reported comfort remains an important measure, even if not entirely captured by objective data.  

The Bottom Line  

So, can temperature-regulating liners enhance outcomes for lower-limb prosthesis users? Initial evidence indicates possible advantages, especially in reducing heat and sweat and improving user comfort. Still, more extensive and longer-term research is necessary to determine if these technologies lead to statistically significant and meaningful improvements in mobility, performance, and long-term health.

But the trend is clear: improving the thermal environment within the prosthetic socket is a promising strategy for boosting comfort and quality of life for individuals with limb loss.   

Related Reading:

Skin Conditions After Limb Loss: What You Need to Know

A Primer on Breathable Prosthetic Liners

SoftskinAir: The Breathable Liner that Combines Comfort and Safety