Coefficient of Friction Measurements on Transfemoral Amputees

Friction at the residual-limb socket interface affects amputees' comfort since it has a direct impact on the pain and functionality of the prosthesis. In this research, the coefficient of friction was measured at the volar forearm and three regions of the transfemoral residual limb (i.e., pressure tolerant, pressure sensitive, and scar region). The socket internal texture was replicated on a probe made of polypropylene to resemble the interface conditions. Besides the anatomical location, the presence and absence of sweat at the interface were evaluated. The statistical analysis included an ANOVA for two-factor experiment with repeated measures on one factor (sweat), where only sweat was found to be statistically significant (p − value = 0.001). Furthermore, regression analysis for the presence and absence of sweat condition was developed since its presence seems to homogenize the interaction conditions by surpassing the effect of other factors on skin friction. The presence of stick-slip phenomenon at the interface, the skin deformation during measurements, and the use of a portable tribometer led to the large variability in results, with larger variability in the presence of sweat. Hence, the relationship between the sweat layer thickness and the coefficient of friction should be explored.