Bionic feet put spring in amputees’ steps

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Prosthetic hands from U.S. Army Medical Research and Material Command at the annual AUSA conference in Washington, DC, October 26, 2010. (Photo: Chris Maddaloni)

At the Army Telemedicine & Advanced Technology Research Center’s booth at AUSA, it was hard to take my eyes off a prosthetic hand so lifelike it looked like there was dirt under the fingernails. Beneath its silicone flesh was a mechanical pincer that, manipulated by the motion of an amputee’s arm and shoulder, opens and closes the thumb, pointer and forefinger.

But after filling me in on the hand, TATRC research scientist Jason Ghannadian wanted to talk feet.

Since the start of the current wars, there have been more than 16,000 amputations across the services, an overwhelming number of which have involved major limbs, and an overwhelming number of which involved soldiers, according to a recent congressional report on casualties.

TATRC guides the recipients of congressional research funding based on what soldiers need most. “There are people who think they have a good idea,” said Ghannadian, “but it might not be useful.”

There are two efforts underway, he told me, to develop a mechanical “powered ankle” that gives amputees the ability to walk more easily than with most other prosthetics, jog or run by cutting some of the energy used to walk. They’re basically bionic feet.

TATRC is funding PowerFootOne, an MIT project, and researchers at Arizona State University, Walter Reed and West Point have been collaborating on an ankle called SPARKy, coming soon to a TV screen near you. According to TATRC:

West Point cadets have designed, built and tested the world’s first lower-leg prosthesis to achieve motorized running. On April 23, filmed by the Discovery Channel, a Special Operations soldier who lost his lower leg in combat used the West Point-SpringActive Bionic Foot to run on a treadmill at 8 mph, the fastest any powered device has ever powered someone.

Most leg prosthetics are dead weight which amputees have to shift around unnaturally using their hips as they walk. The ankles in development contain an electronically governed spring that works more like a natural ankle by giving steps a little, well, spring.

The spring returns some of the energy used to step down, making those steps lighter. Lighter steps mean amputees conserve energy, and get less sweaty and blistered where the flesh and prosthetic meet.

“We know we’re complete when we can restore natural walking, walking to and from the store, walking up and down stairs. That’s one of our main goals,” said Tom Sugar, of ASU Polytechnic Campus. “And the second goal, ultimately, we know we would be finished when a soldier could return to active duty.”
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  1. Joe,
    I REALLY enjoyed this story. My own long-standing belief is that for hundreds of years the U.S. has used up soldiers like they were discards. This says someone (private industry, universities) are really trying to create something amazing for some of the war victims. Great job.
    Mark.

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