Improved artificial limbs save cost and time

Copyright: University of Melbourne

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  • Pressure cast socket technology offers quick and affordable basic prosthetics
  • It frees up prosthetists in developing countries to treat complex amputees
  • It is a portable technique especially useful for large emergency situations

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[SYDNEY] Biomechanical engineers have successfully completed clinical trial of a new technology to make artificial limbs accessible and affordable for thousands of accident and landmine victims in developing countries.

The team led by Peter Vee Sin Lee from the mechanical engineering department of the University of Melbourne fitted 70 patients in Vietnam with prosthetic sockets using pressure cast (PCAST) technology.

“About 400 patients have benefitted from this technology and have found it very comfortable.”

By VIETCOT director Nguyen Hai Thanh

A trans-tibial [below knee] prosthesis consists of the socket (the connection between the user and the prosthesis), the shank and the foot. While the International Committee of the Red Cross’s standard polypropylene components work well for the shank and the foot, the socket has to be customised to every patient’s need by a prosthetist.

“PCAST process takes less than 15 minutes to cast the socket. It doesn’t require any modification or adjustment by a prosthetist. The technique is suited for sockets needed by the largely trauma victims in developing countries”, Lee notes, though he adds more research will be needed for complex cases such as diabetes and vascular related amputations.

To fabricate a PCAST socket, the residual limb is wrapped in a plaster bandage and placed into the PCAST tank attached to a tap. As the water rushes in, the water pressure moulds the plaster cast to the exact shape of the patient’s residual limb. A polypropylene sheet is draped on the mould and heated in an oven to create the socket, which is then fitted to standard ICRC components for the shank and foot.

“Being easily portable, the PCAST technology would be particularly useful in natural disasters and emergency situations to get people walking as soon as possible,” says Lee.

It would also allow prosthetists to focus on more complex cases, such as residual limbs with sensitive tissues or sores that require hand casting of sockets.

Lee and his team have been working with the Vietnamese Training Centre for Orthopaedic Technologists (VIETCOT) in Hanoi, Vietnam, and plan to take the PCAST technology to Cambodia, Laos and Myanmar.

“About 400 patients have benefitted from this technology and have found it very comfortable. In Vietnam, a prosthesis costs US$130 and takes eight hours to make whereas the PCAST prosthesis costs US$100 and takes about four hours to [complete],” VIETCOT director Nguyen Hai Thanh tells SciDev.Net over email.

Louise Puli, chair of the International Society of Prosthetics and Orthotics Australian Outreach Committee, notes: “This technology means that at times, in areas where a highly trained, highly skilled prosthetist is not always available, a reliable and repeatable cast-taking mechanism will exist.”

According to a 2004 WHO report, more than 75 percent of developing countries have no prosthetics and orthotics training programmes.

Puli adds some island countries in the Pacific have no prosthetic service at all. In Africa, the estimated need for prosthetists is about 10,000 professionals, but the current number is less than 400.

Based on her experience in public health as a prosthetist and orthotist in Australia, Cambodia and Tanzania, Puli says, “There are good quality low-cost prosthetic parts available in developing countries, but even the very best technological prostheses will not be accepted by the patient if the socket has not been accurately cast and fabricated.”

This piece was produced by SciDev.Net’s South-East Asia & Pacific desk.