During a break in rehearsals for Dancing with the Stars, Purdy, 34, whose legs were amputated below the knees when she was 19, displayed the special prosthetics molded to fit high heels.
"I wasn't able to get the hip motion with my everyday feet," she tells PEOPLE. "So I decided to try these other feet. I originally got these just thinking they were a little bit prettier and I could wear a taller heel and maybe for a tango."
When she attached them, "It freed my hips up so that I could move how I wanted to," she explains.
"Dirty Purdy" and partner Derek Hough have wowed the judges, consistently earning top scores – while keeping everything in perspective with a sense of humor.
"One of the good things is, you never hear her complain about her feet," says Hough. "Normally it's 'Oh my feet, they're killing me! My blisters are bleeding and I gotta to change my shoes! With Amy it's no complaints. Brilliant."