PCAST System Makes Affordable Prostheses Possible
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Around 80% of the world’s disabled population resides in low- to middle-income countries, where there is a lack of prosthetics training programs and a shortage of trained prosthetists. To address this issue, professor Peter Lee from the University of Melbourne in Australia has developed the pressure-casting (PCAST) system.
This system is currently being used to create prostheses in regions with limited resources and a scarcity of trained prosthetists, such as Indonesia, Vietnam, and Tanzania.
In an interview with Pursuit, the University of Melbourne’s research news website, Lee said: “Our work shows that you don’t need fancy equipment to make good prostheses.”
Traditional prosthetic fitting difficulties
A well-fitting prosthetic limb, particularly the socket, is crucial for people with lower-limb loss as it allows painless, comfortable movement. A poorly fitting prosthetic socket can put excessive pressure on the residual limb’s sensitive areas, leading to skin irritation and even damage.
The patellar-tendon-bearing (PTB) socket is the most used prosthetic socket design. It was designed in the 1950s to dispense pressure to areas of the residual limb that can tolerate more pressure.
However, making these sockets requires multiple fittings and adjustments by a skilled prosthetist, which makes the process labor-intensive and time-consuming. For people with lower limb loss in low- and middle-income countries, it would be challenging to acquire a simple, well-fitting prosthetic socket.
To find a more accessible solution, Lee and his team developed the PCAST system. This system reduces the required skill level and minimizes the time and cost of producing a prosthetic socket.
How PCAST works
The PCAST system requires only a plaster wrap, a portable tank, a weighing scale, and water supply. To create a prosthetic socket, the residual limb is first wrapped in a plaster cast, waterproofed with a plastic membrane, and placed in a water tank.
The patient is then instructed to distribute their body weight evenly on the PCAST system and a weighing scale as the water fills the tank. This allows the water to apply uniform pressure on the plaster cast, shaping it to the residual limb.
Image: YAKKUM
Once the plaster cast has been set, the water pressure is reduced. The prosthetist makes a positive mold of the plaster cast, which is then used to create the final prosthetic socket by laminating it with heated thermoplastic or resin.
Sharing the technology
With funding from the CASS Foundation, a private philanthropic organization, and the Rotary Club of Richmond, Lee and his team ran the first trial of the PCAST system in Vietnam. They collaborated with VIETCOT, a training center for orthopedic technologists in Hanoi.
VIETCOT technicians have successfully developed PCAST prosthetic sockets for 32 volunteers. These volunteers have used the sockets regularly for five months and reported high satisfaction levels. Furthermore, their performance in physical tests has shown improvement over time.
In addition, a study to compare PCAST and PTB sockets was conducted with 17 volunteers in Vietnam. The research found no substantial differences between the sockets in terms of the volunteers’ comfort, gait, function, mobility, or socket preference.
After Vietnam, Lee focused on sharing the PCAST system with local practitioners in Tanzania and Indonesia.
In Indonesia, Lee collaborated with rehabilitation provider YAKKUM to create 133 PCAST sockets. These prosthetic sockets have been particularly beneficial for individuals in remote areas with limited access to limb-fitting facilities.
Additionally, Lee is involved in The 100 Limbs Project in Tanzania. The project aims to produce PCAST sockets for rural-area residents with limb loss and train healthcare professionals to utilize the PCAST system to create high-quality sockets. This initiative is a joint effort with Global Peace Network, a Canadian non-governmental organization that employs distance education to provide rehabilitation services in remote regions.
Lee and his team are dedicated to expanding the reach of this method to more healthcare professionals in low- and middle-income countries, with the goal of enhancing mobility and independence for more individuals.
Moreover, due to the efficiency and reduced skill requirements of the PCAST system compared to traditional socket-making techniques, Lee anticipates that it will enable prosthetists to allocate more time to patients with complex needs.
