In this month's New England Journal of Medicine, researchers from the Center for Bionic Medicine at the Rehabilitation Institute of Chicago revealed their success with a robotic prosthetic leg that "learns" to operate based on feedback from the brain of the person it is attached to. The bionic leg could make it possible for people with above-knee amputations to walk, climb stairs, and move the leg while seated, much like a natural leg.

The bionic leg, the result of work under an $8 million research grant from the Department of Defense, uses sensors to pick up electromyographic (EMG) impulses from nerves in the remaining thigh muscle tissue in the patient's leg. The researchers were able to give the patient the ability to control the leg's actions by thinking about moving the leg.

"EMG signals were decoded with a pattern-recognition algorithm and combined with data from sensors on the prosthesis to interpret the patient's intended movements," the team, headed by RIC lead scientist Levi Hargrove, wrote in the article. "This provided robust and intuitive control of ambulation—with seamless transitions between walking on level ground, stairs, and ramps—and of the ability to reposition the leg while the patient was seated."

The patient, Zac Vawter, lost his leg in a motorcycle accident in 2009. He told a reporter from a CBS Chicago affiliate that the leg was "intuitive. It puts energy into me walking and moving around.”

Hargrove told Military Times that the researchers hope to "make this robust enough to send home with people for trial in three to five years. After that, if it gets more funding, [we hope] to have veterans at Walter Reed or San Antonio testing them.”