Some higher-end prosthetic legs are equipped with things like gyroscopes and accelerometers, in order to guide their knee joint through a more natural bending motion. In developing nations, however, such expensive prostheses usually aren't an option. That's why a scientist from MIT is developing a knee that could allow inexpensive legs to perform like the fancy ones.

Instead of hydraulics, electronic sensors or other high-tech goodies, the prototype knee designed by mechanical engineer Amos Winter operates mainly via a spring and two dampers.

The spring bends the knee forward as the prosthetic foot pushes off the ground, while the two dampers essentially act as brakes – one of them keeps the knee (and attached prosthetic calf) from swinging backward, while the other slows it down on its forward stride, so that it's not moving too fast when the heel hits the ground.

Winter and colleagues designed the knee to provide approximately the same amount of torque as is delivered by a real knee, which should let users maintain a smoother gait. By contrast, the prostheses used by many people in developing nations don't have a bending knee at all, causing them to walk with a very pronounced limp.

The scientists have now begun testing the knee with lower-leg amputees in India.

Researchers at Stanford University have also developed a low-cost prosthetic knee, which they hope to sell for under US$20.

Source: MIT

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