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Researchers Develop Artificial Legs That Mimic Real Ones


When we walk, most of us don't give the process a second thought. Tiny electrical signals contract the leg muscles to help the joints move. All of it is controlled by our brains.

Researchers have been working on developing artificial legs that mimic this natural leg movement.

Terry Karpowicz, who is testing one such robotic leg at the Rehabilitation Institute of Chicago, said it "allows me the opportunity to flow down the stairs and not really think about the process of what the next step is.”

The motorized limb harnesses electromyographic (EMG) signals generated by the upper leg muscles.

“We pick them up with tiny antennas called electrodes," said Levi Hargrove of the Rehabilitation Institute, who led the research that produced the device. "When the electrodes touch the skin you can detect the EMG signals, and we pick those signals up and decode them.”

The knee and ankle are thus motorized to replicate normal movement. “With this prosthetic leg, the power pushes you along," Hargrove said. "It can push you up and out of a seat. It can push you up stairs or slopes.”

At the University of Linz in Austria, professor Hubert Egger has just unveiled the first prosthetic leg that can send feelings to the brain like a real leg. Surgeons rewired an amputee's remaining nerve endings from his foot to tissue in the thigh.

Sensors are fitted to the sole of the prosthetic foot and linked to artificial stimulators connected to the stump. The device also allows the person wearing it to feel the ground.

Program participant Wolfgang Rangger said that with this artificial leg, he can tell what kind of surface he's walking on, and in winter, he no longer slips on ice.

Egger is trying to find a way to reduce the cost of his prosthesis so more people can benefit, including those in developing countries.

The participants in both programs expressed a renewed sense of wholeness. Hailey Danisewicz, who took part in the Chicago study, said that "this is the closest I've gotten to having two legs again. What we're working on in this lab is eventually going to change the lives of amputees everywhere. I mean, it's great."

The study conducted at the Rehabilitation Institute of Chicago was published in the Journal of the American Medical Association.

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