"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.
AP Medical Writer Carla K. Johnson can be reached at http://www.twitter.com/CarlaKJohnson.
Copyright 2012 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.