Prosthetic Component Manufacturing in Vietnam: Knee Joint
Amputees with above knee amputations require an artificial knee joint in order to walk again. Such knee joints are difficult to manufacture and, therefore, expensive. To encourage a local supply of durable and affordable prosthetic knee joints, the Prosthetics Outreach Foundation (POF), with support from the Carl J. Herzog Foundation, partnered with the Orthopedic Technology and Rehabilitation Center (OTRC) in Ba Vi to manufacture artificial knee joints in Vietnam that can be serviced locally.
After considerable research and with the assistance of Alan Aulie, an experienced independent prosthetic knee designer in the United States, POF determined that the most practical approach was a single axis knee design. Modifications were made to the original Aulie Knee design to simplify the alignment and attachment to the socket. A single bolt attachment is used, and alignment is adjusted using the concave surface machined into the nylon knee body.
Since the initial field trials, several design improvements have been made based on patient feedback and suggestions from local orthopedic technologists. For example, the return springs have been strengthened, the pylon clamp screw improved, and the flexion range extended. With the help of a Vietnamese composite material specialist, POF has now developed a molded thermoplastic composite knee joint version. The molded joints have proven their durability through fatigue testing and cost significantly less to produce. The reduction in machining times has also help to expedite the filling of orders.
As of May 2007, more than 500 units of the nylon and composite knee joints have been manufactured by OTRC and fitted to children and adult amputees in Vietnam, Bangladesh, and Sierra Leone.
The OTRC knee joint in action!
A young boy takes his first steps with a new limb during a POF outreach trip
The general technical specifications of the knee are as follows:
- Modular design
- Adjustable extension assist (return spring)
- Durable nylon carbon composite frame
- Appropriate for most levels of transfemoral fitting
- Angular alignment adjustment
- Standard 30 mm tube connection
- Replaceable bushings and shafts
- Weight: 550 grams