Zac Vawter, a 31-year-old amputee, aims to make medical history Sunday
when he attempts to climb 103 stories to the top of the Willis Tower with his
state-of-the-art bionic leg.
Researchers at the Rehabilitation Institute of Chicago equipped Vawter
with the prosthetic limb after he lost his right leg in a motorcycle accident
in 2009. Their innovative design allows him to control the leg with his
thoughts, a groundbreaking medical achievement that’s been years in the making.
“The first time that we went up and down stairs was a little clunky and not
particularly smooth,” said Vawter, a software engineer from Yelm, Wash. “Now
I’m comfortable taking a hand off of the railing.”
The climb, called “SkyRise Chicago,” will be the bionic limb’s first
public appearance and its most grueling test, said lead researcher Levi
Hargrove. Vawter said his goal was to make it the top in one hour. With about
2,700 people registered to climb alongside him, the event is serving as a
fundraiser for the institute.
Hargrove said the leg worked by responding to electrical impulses from
the muscles in Vawter’s upper leg, including his rewired hamstring. That’s
where the surgeon who amputated his leg reattached the dangling nerves that
previously carried signals past his knee. The procedure, known as targeted
muscle reinnervation, allowed Hargrove and his team at the institute’s Center
for Bionic Medicine to tap into the preserved neural signals to control the
prosthetic limb. “He just thinks about moving his ankle,” Hargrove said as an
example. “He thinks about doing those movements and the signals travel down the
nerves and are redirected onto hamstring muscle. The body doesn’t know that the
ankle is not contracting. It is very intuitive for him.”
That the U.S. Department of Defense is funding the five-year, $8-million
research project hints at the bionic leg’s potential. Hargrove said injured
veterans who lost legs in combat had much to gain from the new technology. But
while bionic arms have been available for several years, their lower-limb
equivalents won’t be on the market for at least a few more. After the climb,
Vawter has to return the leg to researchers who will work to fine tune its
steering.
Hargrove said safety was his top concern and the largest hurdle to
overcome before the leg could be sold commercially. A malfunctioning leg could
cause its wearer to stumble, or worse — fall down a flight of stairs. “We have
to make sure our system is really safe and robust to prevent those sorts of
injuries,” Hargrove said. “It’ll be a few years.”
Source: Chicago Tribune
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