Does activity affect residual limb skin temperatures?

BACKGROUND: Many lower limb amputees experience thermal discomfort as a result of wearing a prosthesis. The development of new prosthetic technology to address thermal discomfort requires an understanding of how activity (or inactivity) affects residual limb skin temperatures and how skin temperatures are mapped across the skin-prosthesis interface.

QUESTIONS/PURPOSES: We studied skin temperatures inside the socket and suspension system of unilateral transtibial amputees to determine the following: (1) Does residual limb skin temperature change as a function of activity and its cessation? (2) If changes occur, are there regional differences (circumferential or proximal-distal) in temperature?

METHODS: Nine unilateral transtibial amputees provided informed consent to participate in this institutional review board-approved study. Residual limb skin temperatures inside their prosthesis were measured at 16 distributed sites using thermistor sensors and a portable data acquisition system. The 150-minute protocol began with a 60-minute seated rest, continued with a 30-minute treadmill walk at a self-selected speed, and concluded after a second 60-minute seated rest. Data from the last minute of each of the three periods were used for analysis.

RESULTS: The skin temperature was 31.0° ± 1.5° C (mean ± SD) at the end of the initial rest period. After 30 minutes of treadmill walking, skin temperature increased to 34.1° ± 1.3° C, an increase of 3.1° C (95% confidence interval [CI], 2.4-3.8; p < 0.001). After the final 60 minutes of rest, the skin temperature was 33.2° ± 1.2° C, 0.9° C lower (95% CI, 0.5-1.2; p < 0.001) than at the end of treadmill walking but 2.2° C higher (95% CI, 1.4-2.9; p < 0.001) than the temperature observed at the end of the initial rest period. Skin temperatures were warmest over the tibialis anterior region (p < 0.006) and decreased from the most proximal to the most distal locations on the residual limb (p = 0.001).

CONCLUSIONS: Walking causes a dramatic increase in skin temperatures inside the prosthesis and subsequent rest of twice the walking duration fails to return temperatures to their initial condition. Rest alone is likely to be insufficient to provide thermal relief without doffing the prosthesis. New prosthetic technology is needed to address this problem. Skin temperatures also varied by residual limb location, suggesting that the development of location-specific technology would be advantageous.