Prosthetic arm with realistic sensation makes ‘life a better place’

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March 14 (UPI) — Researchers at the Cleveland Clinic have developed a prosthetic arm with more natural movement sensation.

With the new prosthetic, patients who had previously undergone targeted nerve reinnervation can direct amputated nerves to remaining muscles. They can “feel” their palm, back of the hand and even felt each finger, according to researchers.

One test participant, 49-year-old-of Amanda Kitts of Bonita Springs, Fla., whose arm was amputated above the elbow in 2006 after a car accident, told UPI it was “amazing.”

She said Dr. Paul Marasco, who leads a research team at the Laboratory for Bionic Integration in Cleveland Clinic’s Lerner Research Institute, has “made my life a better place.” His research was published online Wednesday in Science.

“By restoring the intuitive feeling of limb movement — the sensation of opening and closing your hand — we are able to blur the lines between what the patients’ brains perceived as ‘self’ versus ‘machine,’ ” Marasco said in a press release. “These findings have important implications for improving human-machine interactions and bring us closer than ever before to providing people with amputation with complete restoration of natural arm function.”

Small but powerful robots vibrate specific muscles to “turn on” patients’ sensation of movement, allowing them to feel their fingers and hands moving, researchers say. With the ability to feel their missing hand, the patients were able to complete complex grip patterns and perform specific tasks nearly as well as able-bodied people.

“I have been going with Paul for about four years,” Kitts said. “And it kind of had a wow moment a couple of years ago. I actually could tell blindfolded where he would touch different parts of the arm and feel like it actually was my hand.”

This is a large improvement from five years ago when she first started feeling sensation with an older prosthetic — including the ability to tell the difference between fingers.

“It feels more realistic,” she said about the newest model. “It feels like it is more part of the body. You can tell when the hand is closed. It makes the whole arm come together. I don’t even have to hook it up to a computer or anything. It’s all in itself. That is fantastic.”

Her spirits are dramatically different than 2006 when she was hit head-on by a Ford F-350 truck in Knoxville, Tenn. Her arm was nearly torn off — the only major injury she sustained — but was later amputated above the elbow.

“I was depressed and in a bad state for a couple years,” said Kitts, who moved to Bonita Springs a few years ago with her husband and son. “These studies have really helped me.”

Six weeks after the accident, she went to the Rehab Institute of Chicago to be fitted for her first prosthetic arm, a basic model without movement.

Cleveland Clinic researchers wanted to replicate how the brain constantly receives feedback regarding the movement’s progress in an unconscious sense that prevents errors in movement. The body can necessary adjustments.

“When you make a movement and then you feel it occur, you intrinsically know that you are the author of that movement and that you have a sense of control or ‘agency’ over your actions,” Marasco said. “People who have had an amputation lose that feeling of control, which leaves them feeling frustrated and disconnected from their prosthetic limbs. The illusions we generate restore the sensation of movement and reestablish their sense of agency over their prosthetics. This helps people with amputation to feel more in control.”

The research team is currently exploring ways to expand use of the technology to patients who have lost a leg, or for those with conditions that impede movement, such as a stroke.

“The ultimate goal of our research is to use movement sensation to streamline the relationship between patients and their technology, to better integrate their prosthetics as a natural part of themselves,” Marasco said.