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New Powered Legs Make Walking As Easy As Thinking

by Maggie Fox /  / Updated 

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A new kind of artificial leg not only powers itself, but lets users control it just by thinking about what they want to do, researchers reported Tuesday.

They’re ready to test the device in real-world situations and will be enrolling injured veterans to try it out at home.

"We have made it really easy for them to command the prosthesis,” said Levi Hargrove of the Rehabilitation Institute of Chicago, who led the study of seven amputees who checked out the device.

"They can tell it very easily what they want it to do; if they want to stand up, if they are trying to walk up stairs," he said.

“They can tell it very easily what they want it to do."

Even the most sophisticated prosthetic legs are passive — they have no extra power and are merely attached to the leg. This new leg has its own power and is also connected to the muscles so that users can control the artificial leg, to some degree, by thinking about what they want to do.

The leg uses electromyographic (EMG) signals, which muscles generate when they contract. Some sophisticated artificial arms use EMG, but until now, prosthetic legs have not.

"Every time a muscle contracts, it generates a little bit of electricity," Hargrove said.

"We can measure that with electrodes and figure out what the person was trying to do," he said. "We have made this really intuitive control system that allows the wearer to just simply walk around and go up and down stairs and it decodes their intentions as they walk."

The device measures these little electric signals from nine muscles in the remainder of the leg, the team reports in the Journal of the American Medical Association.

Prosthetics researchers have made artificial hands that can let users "feel" what they are touching,thought-controlled arms, and now a leg that can let the user feel.

But they’re not all slam dunks. Some veterans have complained their prosthetics are difficult to use.

This one isn't hard to use, says Terry Karpowicz, a 67-year-old sculptor who lost a leg 40 years ago in a motorcycle accident.

"This bionic leg lets me move naturally, like I did before my amputation," Karpowicz said.

"For the first time in more than 30 years, I can experience my environment without thinking about which movement I want to make, because this leg does the thinking for me," he said.

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