Bionic arm allows amputees to move limb with thoughts

Defense Department to offer advanced prosthesis to injured soldiers

September 14, 2006|By Ronald Kotulak | Ronald Kotulak,CHICAGO TRIBUNE

Ex-Marine Claudia Mitchell didn't lose her left arm in battle, but she is the first woman to be fitted with a thought-controlled bionic arm that the U.S. Defense Department plans to begin offering this year to soldiers who have lost limbs in Iraq and Afghanistan.

A resident of Ellicott City, she lost her arm in a motorcycle accident two years ago. Now, Mitchell is slated to help military amputees adjust to new bionic arms like hers, developed at the Rehabilitation Institute of Chicago.

If the other amputees do as well as Mitchell, who can move her elbow and wrist at the same time -- something not possible before with any motorized prosthesis -- they will be able to perform activities more proficiently.

Mitchell, 26, says she simply has to think to move her arm -- a far cry, she said, from her first replacement limb, which was so hard to work that she gave up in tearful frustration.

"I can flex my elbow, extend my elbow, open and close my hand with the mere thought of doing it," she said of her new arm Tuesday while in Chicago to help RIC researchers test an even more advanced thought-controlled prototype. Yesterday, the team was in Washington to show off the experimental model to military brass.

"I can carry a tray," Mitchell said. "I can open a jar. I can hold my Dagwood sandwich. I can hold fruit and vegetables while I cut them up. I can peel a banana.

"This makes daily life much easier, especially in the kitchen. ... That's where I found the most difficulty in doing things with one hand. So I am much more adept in the kitchen now, which my family is pretty excited about."

Mitchell is the fourth person to be successfully fitted with RIC's bionic arm, which weighs about 6 pounds and costs between $60,000 and $75,000. She says she typically wears the arm two to eight hours a day.

The arm works by surgically moving the four main nerves that used to connect the brain to the missing limb so they communicate with the computerized arm instead, a breakthrough pioneered by Dr. Todd Kuiken, director of RIC's Neural Engineering Center for Artificial Limbs and Center for Bionic Medicine.

To do this, the nerves are rerouted from the stump to muscles in the chest. The nerves still carry the electric signals from the brain that formerly activated the arm, and by placing sensors over the nerves these signals can be used to operate the artificial prosthesis, which is equipped with three motors and a small computer.

"This arm feels very natural as far as the way I can flex and open and close my hand," said Mitchell, who served in the Marines for four years and is now on inactive ready reserve. "The first prosthesis I had, my frustration was out the roof. I would cry. It was extremely frustrating to the point where I wouldn't wear my arm. With this arm all I have to do is think. I think I want my arm to go down, it goes down. I want my arm to go up and here I go."

Kuiken, who developed the bionic arm primarily with funding from the National Institutes of Health, said the work is moving into a new phase as part of an initiative by the Defense Advance Research Projects Agency, or DARPA, to revolutionize prosthetic devices for amputee soldiers.

Kuiken said he is working with doctors at Walter Reed and Brooke Army medical centers, where amputees are taken to recover. "We're hoping to be able to apply this technology to U.S. service men and women this year," he said. "We aren't doing a real great job with upper-limb prostheses. Our challenge is to restore function for people who have suffered limb loss."

This year DARPA awarded nearly $50 million to two teams of researchers with the goal of providing the most advanced medical and rehabilitative technologies for military personnel injured in the line of duty. RIC scientists are working with both teams.

One of the teams, led by the Applied Physics Laboratory of the Johns Hopkins University, will work on a bionic arm that can operate like a biological one, including the ability to feel objects and manipulate them with precise movements. The second team, headed by DEKA Research and Development Corp. in Manchester, N.H., will concentrate on providing near-human strength to the artificial arm.

The possibility of making a bionic arm that can feel came to light with Jesse Sullivan, a double amputee from Tennessee who was the first person to receive RIC's thought-controlled prosthesis. Kuiken and his team were startled to discover that touching the skin over the chest muscles where the arm nerves had been transplanted gave Sullivan the feeling that a part of his hand was being touched.

Working with Dr. Gregory Dumanian, a Northwestern Memorial Hospital plastic surgeon, Kuiken carefully rerouted Mitchell's arm nerves to an area on her chest about the diameter of a baseball. When the area is touched, she gets the sensation that precise areas of her missing hand are being touched.

Ronald Kotulak writes for the Chicago Tribune.

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