300 knee joints have been fitted to amputees in India, where Joel Sadler of Stanford’s Mechanical Engineering lab 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 $20.
high-end titanium knee joints start at $10,000. The JaipurKnee, was developed by Sadler, 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.
Time Magazine listed the Jaipur Knee as one of the best inventions of 2009.
Last updated: December 26th, 2025
