Effect of temperature-control liner materials on long-term outcomes of lower limb prosthesis use: a randomized controlled trial protocol

Assessing Phase-Change Materials as Effective Long-Term Biosensors in Limb Prosthetics

Monitoring and controlling the microclimate at the skin-socket interface of limb prostheses is an important, yet unresolved, clinical problem. Phase-change materials (PCMs) represent a promising biosensor technology that holds the potential to both detect and alter (i.e., stabilize) changes in the temperature of a hybrid biological/mechanical system, such as a prosthesis. The biologically inspired sensor capabilities of PCMs can enhance the internal socket conditions and offer improved comfort and suspension while minimizing skin injuries for prosthesis users. This study investigated how prosthetic liners equipped with PCM biosensors affected the long-term outcomes for prosthesis users. In this double-blinded longitudinal crossover study, a cohort of transtibial prosthesis users wore regular conventional liners for six months and PCM liners for another six months. Prosthesis utilization, physical performance, and gait symmetry were studied using Modus StepWatch, the 2-minute walk test, and the TekScan F-Scan gait test, respectively. Measured parameters from these various tests, acquired at multiple timepoints during the study, were compared pairwise between the two liners per individual. While the obtained quantitative data trends, such as the gait symmetry, favored the PCM liners, no statistically significant differences were found between the PCM and conventional gel liners in any of the study parameters.

Moisture mitigation using a vented liner and a vented socket system for individuals with transfemoral amputation

Sweating and heat buildup at the skin-liner interface is a major challenge for persons with limb loss. Liners made of heat-non-conducting materials may cause sweating of the residual limb and may result in liners slipping off the skin surface especially on a warm day or during high activity, causing skin breakdown and affecting limb health. To address this, we evaluated the efficacy of the vented liner-socket system (VS, Össur) compared to Seal-In silicone liner and non-vented socket (nVS, Össur) in reducing relative humidity (RH) during increased sweat. Nine individuals with limb loss using nVS were randomized to VS or nVS and asked for activity in a 20-min treadmill walk. RH was significantly attenuated (p = 0.0002) and perceived sweating, as reported by prosthesis users, improved (p = 0.028) with VS, patient-reported comprehensive lower limb amputee socket survey (CLASS) outcomes to determine the suspension, stability, and comfort were not significantly different between VS and nVS. There are limited rigorous scientific studies that clearly provide evidence-based guidelines to the prosthetist in the selection of liners from numerous available options. The present study is innovative in clearly establishing objective measures for assessing humidity and temperatures at the skin-liner interface while performing activity. As shown by the measured data and perceived sweat scores provided by the subjects based on their daily experience, this study provided clear evidence establishing relative humidity at the skin-liner interface is reduced with the use of a vented liner-socket system when compared to a similar non-vented system.

Measuring residual limb health in persons with upper limb amputation: Modifications of the Prosthetic Evaluation Questionnaire residual limb health scale

BACKGROUND

Assessing the user perspective on residual limb health problems is particularly important for amputation care, given the relationship between residual limb health and prosthetic satisfaction. Only 1 measure, the Residual Limb Health scale of the Prosthetic Evaluation Questionnaire (PEQ) has been validated for use in lower limb amputation, but not examined in persons with upper limb amputation (ULA).

OBJECTIVES

The objective of this study was to examine the psychometric properties of a modified PEQ Residual Limb Health scale in a sample of persons with ULA.

STUDY DESIGN

The study involved a telephone survey of 392 prosthesis users with ULA, with a 40-person retest sample.

METHODS

The PEQ item response scale was modified to a Likert scale. The item set and instructions were refined in cognitive and pilot testing. Descriptive analyses characterized the prevalence of residual limb issues. Factor analyses and Rasch analyses evaluated unidimensionality, monotonicity, item fit, differential item functioning, and reliability. Test-retest reliability was assessed by an intraclass correlation coefficient.

RESULTS

Sweating and prosthesis odor were prevalent at 90.7% and 72.5%, respectively; blisters/sores (12.1%) and ingrown hairs (7.7%) were the least prevalent problems. Response categories were dichotomized for 3 items and trichotomized for 3 items to improve monotonicity. After adjusting for residual correlations, confirmatory factor analyses showed acceptable fit (comparative fit index = 0.984, Tucker-Lewis index = 0.970, and root mean square error approximation = 0.032). Person reliability was 0.65. No items had moderate-to-severe differential item functioning by age or sex. Intraclass correlation coefficient for test-retest reliability was 0.87 (95% CI, 0.76-0.93).

CONCLUSIONS

The modified scale had excellent structural validity, fair person reliability, very good test-retest reliability, and no floor or ceiling effects. The scale is recommended for use with persons with wrist disarticulation, transradial amputation, elbow disarticulation, and above-elbow amputation.

Does socket liner material affect clinical outcomes in lower limb prosthesis users? Insights from a randomized control trial

Among the noted disadvantages of prosthesis suspension by flexible liner is the increased rate of perspiration within the socket, which has the potential to cause discomfort, suspension issues, and tissue damage. In recent years, phase change material technology has been adopted for the use in prosthesis liners. These promise to improve temperature control and, consequently, reduce sweating. Previous work has demonstrated that this approach is effective in slowing the temperature increase at the limb-socket interface, but it was not clear how this would translate to clinical outcomes. This study had the aim to compare conventional and phase change material liners regarding prosthesis utilization, physical performance, and patient-reported outcome measures. A randomized double-blind cross-over study design with 6-month intervention periods was used. Of the 42 enrolled participants, only 50% completed the protocol. The high attrition was in large part because of the COVID-19 pandemic that started disrupting daily life and thereby the data collection midway through the study period. The findings indicate that the temperature control liners were, by trend, associated with better prosthesis utilization. The found effects did not reach the level of statistical significance, which is likely a result of the unduly reduced sample size.

Experimental thermal analysis of a novel prosthetic socket along with silicone and PCM liners

Prosthetic liners and sockets insulate a residual limb, causing excessive heat, sweating, skin irritation and maceration. Circulation of a fluid through the socket wall has been shown to have positive cooling effects on the internal surface of the socket, i.e. skin temperature. Moreover, Phase Change Materials (PCMs) have been recognized as a practical method for cooling garments. These materials, such as water or many synthesized polymers, have a high latent heat and their application within a prosthetic liner allows for absorbing heat from the limb for retaining a constant temperature. In this study, a novel prosthetic socket has been designed and prototyped to investigate the interactive effects of fluid circulation and PCM materials on thermal comfort of prosthetic sockets. The results indicate a statistically significant difference (p-value < 0.001) in the duration a PCM liner can retain the appropriate skin temperature, compared to regular silicone liners. Likewise, the presence of air circulation within the socket wall was shown to have statistically significant influences (p-value = 0.018) on providing the efficient cooling effects compared to regular sockets. Hence, incorporating circulation cooling mechanisms along with PCM liners as proposed in this study holds a promising solution to enhance the thermal comfort of prosthetic socket systems.