Rehabilitation and adaptation of lower limb skin to friction trauma during friction contact

Most amputees usually use prostheses to retain upright mobility capabilities and restore appearance. A prosthetic socket is a fitting between the prosthesis and the trans-tibial stump, which is the critical component for prosthetic performance and the only way of load transfer between the prosthesis and the stump. However, the skin of an amputated limb is not adapted to bearing load. The interaction between the stump and the prosthetic socket usually causes dermatologic problems. A total of 34% of amputees experienced skin problems, such as pressure ulcers, blister, cysts, edema, skin irritation, dermatitis, etc, which result from friction, pressure, heat and humidity. This would affect the wear of the prosthesis. In this paper, skin self-rehabilitation and self-adaptation to friction trauma were studied by means of friction testing, skin surface characterization, skin trauma and skin sensation evaluation. The human limb skin was investigated in vivo under the simulated friction conditions of mobility capability training of amputees who preliminarily wear prosthesis. Results showed that in the 30 days׳ friction trauma and rehabilitation process, the trauma degree of skin surface was from severe to slight, the skin surface roughness values increased first and decreased later, and then increased again. Keratinization gradually formed on the skin surface, and correspondingly, the coefficient of friction decreased first and then increased. The differences of skin temperature from friction test start to end gradually decreased with increasing friction days. The EEG signal examinations suggested that the discomfort sensations gradually weakened with increasing friction days. These results demonstrated that the limb skin went through the tribological behavior from friction trauma to gradual self-adaptation under a long period of reciprocal sliding friction condition. The results would be useful for the new amputee to arrange the best policy of capability training, and would also guide the correct use of labor and sporting goods.