Evaluation of use and durability of polypropylene trans-tibial prostheses

Forty-three (43) trans-tibial prostheses with a mean period of use of 33 mo nths were evaluated in terms of utilisation and durability. The majority of the prostheses (80%) were worn by amputees with demanding occupations, suc h as farmers, fishermen and tradesmen. The prostheses were in use approxima tely 9 hours per day. No major or frequent breakdowns of the polypropylene prosthetic components were found. The suspension belts were the parts most frequently affected; a total of 32 needed replacement after an average 11 m onths of use. Eleven (11) prostheses were completely replaced, more than ha lf at least partly because of socket-fitting problems. In all, socket-fitti ng problems were found in 15 prostheses, causing pain and consequently limi tation of use. While the prosthetic polypropylene components were satisfact ory, the rubber foot was a major cause of early breakdown. A total of 40 fe et were replaced; their mean period of use before breakdown was 9 months. I n practice, parts were frequently replaced at a later stage than desirable, meaning that there was frequent "overuse" of prostheses with worn parts. M easures were taken to increase the life span of the prosthesis: change in t he design of the foot; issuing a spare foot with the prosthesis; strengthen ing the suspension belt. Additional evaluations are necessary to confirm th e degree to which the findings are representative.