A Water-Based Pressure Casting Method for Transtibial Prosthetic Socket Fit in Developing Countries

Abstract

Many challenges are faced by large numbers of people with lower limb amputation in developing countries. Foremost are cost and access to skilled prosthetic services. Attempts have been made to develop socket fabrication techniques that require little or no prosthetic skill. This study investigated a water pressure casting technique (PCAST) to fabricate and fit transtibial (TT) prosthetic sockets. Ethics approval and informed consent were obtained. Fifty-three adults with unilateral TT amputation were recruited from VIETCOT (Hanoi). VIETCOT staff with ISPO category II qualifications fabricated and fitted the prostheses. Firstly, a cotton sock was placed over the residual limb followed by a plaster wrap. The participant stood with the intact limb on a weight-scale and placed the residual limb into a plastic bag-type diaphragm housed in a cylindrical tank filled with water until they stood normally with half body weight supported. Upon hardening a positive plaster model was made and a socket fabricated with a distal pelite cap. A polypropylene socket was then moulded and attached to ICRC prosthetic components and a rubber foot. The same person fabricated, fitted and aligned the prosthesis. Once a participant indicated satisfaction, the following tasks were completed: timed up-and-go (TUG), six-minute walk (6MWT), walking (GAITRite mat) and satisfaction questionnaire (SATPRO). These tasks were also completed after an extended usage period (146 ± 28 days). Thirty-one of the participants were successfully fitted: fourteen fits failed, eight failed to return, withdrew or became deceased. SATPRO (n = 31) showed high levels of satisfaction (81%) on both test occasions. 6MWT increased by 28 m (p = 0.01) after the usage period. TUG, SATPRO and gait measures remained unchanged. A sub-analysis (n = 21) compared PCAST performance to original socket and prosthesis. No differences were found. In conclusion, the PCAST may assist people with TT amputation in developing countries.