Man With Bionic Leg To Climb Willis Tower In Chicago

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CHICAGO (AP)
— Zac Vawter considers himself a test pilot. After losing his right leg
in a motorcycle accident, the 31-year-old software engineer signed up
to become a research subject, helping to test a trailblazing prosthetic
leg that's controlled by his thoughts.

He will
put this groundbreaking bionic leg to the ultimate test Sunday when he
attempts to climb 103 flights of stairs to the top of Chicago's Willis
Tower, one of the world's tallest skyscrapers.

If
all goes well, he'll make history with the bionic leg's public debut.
His whirring, robotic leg will respond to electrical impulses from
muscles in his hamstring. Vawter will think, “Climb stairs,” and the
motors, belts and chains in his leg will synchronize the movements of
its ankle and knee. Vawter hopes to make it to the top in an hour,
longer than it would've taken before his amputation, less time than it
would take with his normal prosthetic leg – or, as he calls it, his
“dumb” leg.

A team of researchers will be
cheering him on and noting the smart leg's performance. When Vawter goes
home to Yelm, Wash., where he lives with his wife and two children, the
experimental leg will stay behind in Chicago. Researchers will continue
to refine its steering. Taking it to the market is still years away.

“Somewhere
down the road, it will benefit me and I hope it will benefit a lot of
other people as well,” Vawter said about the research at the
Rehabilitation Institute of Chicago.

Bionic -
or thought-controlled – prosthetic arms have been available for a few
years, thanks to pioneering work done at the Rehabilitation Institute.
With leg amputees outnumbering people who've lost arms and hands, the
Chicago researchers are focusing more on lower limbs. Safety is
important. If a bionic hand fails, a person drops a glass of water. If a
bionic leg fails, a person falls down stairs.

The
Willis Tower climb will be the bionic leg's first test in the public
eye, said lead researcher Levi Hargrove of the institute's Center for
Bionic Medicine. The climb, called “SkyRise Chicago,” is a fundraiser
for the institute with about 2,700 people climbing. This is the first
time the climb has played a role in the facility's research.

To
prepare, Vawter and the scientists have spent hours adjusting the leg's
movements. On one recent day, 11 electrodes placed on the skin of
Vawter's thigh fed data to the bionic leg's microcomputer. The
researchers turned over the “steering” to Vawter.

He kicked a soccer ball, walked around the room and climbed stairs. The researchers beamed.

Vawter
likes the bionic leg. Compared to his regular prosthetic, it's more
responsive and more fluid. As an engineer, he enjoys learning how the
leg works.

It started with surgery in 2009.
When Vawter's leg was amputated, a surgeon repositioned the residual
spaghetti-like nerves that normally would carry signals to the lower leg
and sewed them to new spots on his hamstring. That would allow Vawter
one day to be able to use a bionic leg, even though the technology was
years away.

The surgery is called “targeted
muscle reinnervation” and it's like “rewiring the patient,” Hargrove
said. “And now when he just thinks about moving his ankle, his hamstring
moves and we're able to tell the prosthesis how to move appropriately.”

To
one generation it sounds like “The Six Million Dollar Man,” a 1970s TV
show featuring a rebuilt hero. A younger generation may think of Luke
Skywalker's bionic hand.

But Hargrove's
inspiration came not from fiction, but from his fellow Canadian Terry
Fox, who attempted a cross-country run on a regular artificial leg to
raise money for cancer research in 1980.

“I've
run marathons, and when you're in pain, you just think about Terry Fox
who did it with a wooden leg and made it halfway across Canada before
cancer returned,” Hargrove said.

Experts not
involved in the project say the Chicago research is on the leading edge.
Most artificial legs are passive. “They're basically fancy wooden
legs,” said Daniel Ferris of the University of Michigan. Others have
motorized or mechanical components but don't respond to the electrical
impulses caused by thought.

“This is a step
beyond the state of the art,” Ferris said. “If they can achieve it, it's
very noteworthy and suggests in the next 10 years or so there will be
good commercial devices out there.”

The $8
million project is funded by the U.S. Department of Defense and involves
Vanderbilt University, the Massachusetts Institute of Technology, the
University of Rhode Island and the University of New Brunswick.

Vawter
and the Chicago researchers recently took the elevator to the 103rd
floor of the Willis Tower to see the view after an afternoon of work in
the lab. Hargrove and Vawter bantered in the elevator in anticipation of
Sunday's event.

Hargrove: “Am I allowed to trash talk you?”

“It's fine,” Vawter shot back. “I'll just defer it all to the leg that you built.”

At
the top, Vawter stood on a glass balcony overlooking the city. The next
time he heads to the top, he and the bionic leg will take the stairs.

Copyright 2012 by The Associated Press. All rights reserved.

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