Man With Bionic Leg Set to Climb 103 Stories

Zac Vawter is a 31-year old software engineer who tragically lost his right leg after a motorcycle accident. Like most amputees, he was outfitted with a typical prosthetic leg that helped him get around. It wasn't until he became a research subject at the Rehabilitation Institute of Chicago that he'd become a genuine bionic man set to make history on Sunday by climbing to the top of Chicago's Willis Tower, one of the world's tallest skyscrapers.

Vawter is outfitted with a bionic leg controlled by his thoughts. His neural-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.

Although "smart" prosthetic limbs have been around for a few years (the Institute launched the first bionic arm in 2005), this will be the first major test of a thought-controlled bionic leg in public. If all goes well, Vawter will climb 103 flights of stairs to the top of the Tower in about one hour.

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.

Vawter has traveled to Chicago every few months from his home outside of Seattle to prepare for the test. He and a team of scientists have spent hours adjusting the leg's movements. Electrodes placed on the skin of Vawter's thigh feed data to the bionic leg's microcomputer. The researchers can control the leg remotely or turn over the "steering" to Vawter.  In a recent test, he kicked a soccer ball, walked around the room and climbed stairs without a hiccup. The team  knew that Vawter and the leg were officially ready for a real challenge.

"One of the biggest differences for me is being able to take stairs step-over-step like everyone else," said Vawter. "With my standard prosthesis, I have to take every step with my good foot first and sort of lift or drag the prosthetic leg up. With the bionic leg, it's simple, I take stairs like I used to, and can even take two at a time."

Perhaps the most remarkable part of this story, however, is what happened three years ago-after Vawter's accident-well before the bionic leg had been developed.  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 to one day be able to use a bionic leg, even though the technology was still years in the offing.

The surgery is called "targeted muscle reinnervation" and it's like "rewiring the patient," said lead researcher Levi Hargrove of the Institute's Center for Bionic Medicine. "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."

Experts in the field from around the world will be eagerly watching Vawker's history-making climb. If he's successful, it will be a good sign that the technology will become commercially available within the next 10 years.