'Zac has been rewired': Washington man on cusp of having truly bionic leg
Washington man tests out his 'bionic leg' [NBC News]

After almost four years of testing, a Washington state man is closer to being able to use a prosthetic leg that responds to his body's commands.

"Compared to my everyday leg, this 'bionic leg,' or the neural prosthetic is dramatically beyond my normal leg," Zac Vawter told NBC News in a report published on Wednesday. "In terms of how it transitions from walking to stairs and sitting and standing and how it helps me move around and puts energy into the motion, it's really a dramatic difference over my normal prosthetic."

Vawter, who lost is right leg in a motorcycle accident in 2009, has been working with researchers at the Rehabilitation Institute of Chicago to develop the enhanced prosthesis. The institute received an $8 million grant from the Army Telemedicine and Advanced Technology Research Center to adapt the technology from a similar prosthesis for a human arm. Researchers told NBC that a version of the new model could be made available to a million Americans within three to five years.

A team at the institute, led by researcher Levi Hargrove, published their findings from working with Vawter on Wednesday in the New England Journal of Medicine.

"Zac has been rewired," Hargrove told NBC. "The nerves that would have went to the muscles that control his ankle have been redirected onto his hamstring. As a result, when he thinks about moving his foot, we're able to decode that naturally and intuitively and tell the bionic leg how to move."

Vawter has not been allowed to take the prototype model of the new leg home, while Hargrove and his team work to correct remaining software errors and make it smaller and lighter.

"My normal prosthetic has tricks that I've had to learn to make it work," Vawter told NBC. "I haven't had to do that with this leg."

Watch NBC's report, posted on Wednesday, below.

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