The new powered ankle-foot prosthesis developed by a team in MIT got off on the right foot during a ceremony at the Providence, R.I., Veterans Affairs Medical Center, wherein an army amputee - Garth Stewart who lost his left leg below the knee in an explosion in Iraq - walked in the device, which, unlike any other, propels users forward using tendon-like springs and an electric motor.

According to MIT Media Lab Professor Hugh Herr, who developed the ankle-foot with his team of researchers:

"This design releases three times the power of a conventional prosthesis to propel you forward and, for the first time, provides amputees with a truly humanlike gait. It's wild, like you're on one of those moving walkways in the airport."

Hugh Herr, NEC Career Development Professor and head of the biomechatronics research group at the Media Lab, is a VA research investigator and is also a double amputee who tested his invention.

Because conventional prostheses only provide a passive spring response during walking, they force the amputee to have an unnatural gait and typically to expend some 30 percent more energy on walking than a non-amputee. The new ankle is light, flexible, and - most importantly - generates energy for walking beyond that which can be released from a spring alone.

This is accomplished through a device equipped with multiple springs and a small battery-powered motor. The energy produced from the forward motion of the person wearing the prosthesis is stored in the power-assisted spring, and then released as the foot pushes off. Additional mechanical energy is also added to help momentum.

Find more details from the full report.

[In Photo: The MIT Media Lab's powered ankle-foot prosthesis in action. Photo by Webb Chappell]