April 23, 2009 An artificial knee costing just USD$20 promises to deliver much needed help to amputees who are disadvantaged or impoverished – particularly when the price of high-end titanium knee joints can range anywhere from USD$10,000 to USD$100,000 in the US. The artificial knee, dubbed the JaipurKnee, was developed by Joel Sadler, a lecturer in mechanical engineering and d'Arbeloff Fellow, and his team at the Hasso Plattner Institute of Design at Stanford University.

Named after the JaipurFoot prosthetics charity, which worked with Sadler and his team, the prosthetic knee was designed by evaluating the mechanics of expensive titanium knee joints in the US as well as the substantially cheaper materials used in prosthetics in developing countries.

Based on these studies, the team came up with a versatile knee joint made from an oil-filled nylon polymer. Previously inexpensive prosthetic knee joints rotated on a single axis, like a door hinge. These proved to be unstable and unsafe on rough terrain and caused amputees considerable physical and mental pain. The mechanics of the self-lubricating JaipurKnee joint are different from other cheaper models and capable of rotating in more than one plane, which makes it more flexible and easier to walk on.

To date, some 43 joints have been fitted to amputees in India, where Sadler and his team are performing further tests to improve on the knee's design. The initial goal is to produce 100,000 joints over the next three years, with the hope that the cost can still be driven below USD$20.

The Jaipur Knee went on display recently at Stanford's annual Cool Product Expo.

David Greig