'Bionic leg' controlled by the mind

By Jodi Mohrmann - Managing Editor of special projects
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SEATTLE, Wash. - There are 2 million people with amputations in the U.S. For many of these patients, prosthetic devices offer greater mobility. Now, researchers are testing a new generation of prosthetics that are like nothing you've seen.

Zac Vawter's amputated leg doesn't slow him down.

"I lost my leg in a motorcycle accident," Vawter said.

He received a prosthetic. It helps him get around, but has its limitations.

"If I were to sit down and leave the knee locked, it would stay locked," Vawter explained.

But this thought-controlled myoelectric leg does what Vawter's prosthetic can't. Before he could use it, Orthopedic Surgeon Dr. Doug Smith took nerves from his lower leg and redirected them to his hamstring muscle.

"Instead of firing when you think about bending your knee, it would fire when you think about raising your ankle," sakd Smith with Harborview/UW Medicine.

When Vawter wants to move the leg, the brain signal travels down his spinal cord, through the nerves; electrodes in the prosthetic pick up signals from the muscles. 

"You can have a prosthetic device that actually works according to your thought," Smith said.

The device is still being studied, so Vawter can't take it home, but he looks forward to the day he can.

"Stairs with that leg, the ‘bionic leg,' is really phenomenal," he said.

Until now, only thought-controlled arms were available. Although the cost of the "bionic leg" hasn't been determined, researchers say a version could be available for consumer use within three to five years.

Additional Information:

Prosthesis is an apparatus that is used to restore the function of a limb with a prosthetic replacement. A prosthetic replacement can reinstate the use of the legs, arms, joints, eyes, and hands. When a person needs a prosthetic limb usually it is because of a tragic accident or disease. When a person has to have an amputation, they are losing the function of that body part. Thankfully, doctors have created prosthetic body parts to replace the function of their biological body part.  (Source: http://www.nlm.nih.gov/medlineplus/ency/article/002286.htm)

BENEFITS: Those who have undergone the process of having a prosthetic limb have been known to have more energy. Those who decided to continue to use crutches and a wheelchair did not have the same amount of energy that prosthetic limb recipients had. Patients who have prosthetic limbs also have more mobility. Those who have prosthetic legs have the ability to go up and down the stairs and reach places that are not wheelchair accessible. Prosthetic limbs also offer a sense of independence that others do not have. (Source: http://www.livestrong.com/article/36509-advantages-prosthetic-legs/)

MODERN PROSTHETIC LIMBS: Prosthetic limbs have advanced throughout the years. They have grown to be lighter, more realistic, and stronger than older prosthetics. They are also easier to grip and walk in, and they provide more comfort. Although prosthetic limbs have evolved from earlier days, each prosthetic is tailored and specific to the person receiving it. (Source: http://science.howstuffworks.com/prosthetic-limb2.htm)

"BIONIC LEG": The latest technology for prosthetics is the "bionic leg."  Scientists have designed a bionic prosthetic leg that can reproduce a full range of ambulatory movements by communicating with the brain of the person wearing it.  The prospects for such connections between a patient's prosthetic and their peripheral nerves are generally dim.  In most amputations, the nerves in the thigh are left to die.   A neurosurgeon at UW Medicine, Dr. Todd Kuiken, pioneered a practice called "reinervation" of nerves severed by amputation.  Dr. Doug Smith was trained to conduct the operations.  He rewired the severed nerves to control some of the muscles in Zac's thigh that would be used less frequently in the absence of his lower leg.  Within just a few months of the amputation, those nerves had recovered from the shock of the injury and began to regenerate and carry electrical impulses.  When Zac thought about flexing his fight foot in a specific way, the rerouted nerve endings would consistently cause a distinctive contraction in his hamstring.  When compared with prosthetics that were not able to "read" the intent of their wearers, the robotic leg programmed to follow Zac's commands reduced the kinds of errors that cause unnatural movements, discomfort and falls by as much as 44 percent, according to The New England Journal of Medicine.  (Source: http://www.orthop.washington.edu/?q=bionic-leg-is-controlled-by-brain-power-article-in-la-times-featuring-dr-douglas-smith.html)

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