Despite losing most of his right leg in a motorcycle accident, Zac Vawter (31) intends to climb all 103 flights of stairs at Chicago's Willis Tower this Sunday. He's been helping researchers at the Rehabilitation Institute of Chicago (RIC) test a cutting-edge bionic leg that is controlled by his own nerve impulses. He can walk, kick a ball, and climb stairs by simply thinking of what he wants his leg to do.
