Bionic knee from MIT researchers gives amputees new motion

Thomas Gee, a former gymnast, used to do handstands, perform wheelies on his skateboard, and run around with his three young children. But in 2001, a marble-sized bump on his left leg swelled to the size of a football. Gee was diagnosed with soft tissue sarcoma, a form of cancer that required the amputation of his leg above the knee.

After his surgery, Gee remained active but switched to walking instead of running with his kids. His prosthetic leg had a suction fit and a hydraulic knee, but it was far from satisfactory.

“I would fall at least once a month,” Gee said. “When you step on an uneven surface and the toe triggers the knee, all of a sudden there’s no resistance anymore, and you just go right straight down.”