Bionic leg takes the next step [Telegraph-Herald (Dubuque, IA)]
(Telegraph-Herald (Dubuque, IA) Via Acquire Media NewsEdge) The act of walking might not seem like a feat of agility, balance, strength and brainpower. But lose a leg, as Zac Vawter did after a motorcycle accident in 2009, and you will appreciate the myriad calculations that go into putting one foot in front of the other.
Taking on the challenge, a team of software and biomedical engineers, neuroscientists, surgeons and prosthetists has designed a prosthetic limb that can reproduce a full repertoire of ambulatory tricks by communicating seamlessly with Vawter's brain.
A report published Wednesday in the New England Journal of Medicine describes how the team fit Vawter with a prosthetic leg that has learned - with the help of a computer and some electrodes - to read his intentions from a bundle of nerves that end above his missing knee.
For the roughly 1 million Americans who have lost a leg or part of one due to injury or disease, Vawter and his robotic leg offer the hope that future prosthetics might return the feel of a natural gait, kicking a soccer ball or climbing into a car without hoisting an inert artificial limb into the vehicle.
Vawter's prosthetic is a marvel of 21st-century engineering. But it is Vawter's ability to control the prosthetic with his thoughts that makes the latest case remarkable. If he wants his artificial toes to curl toward him, or his artificial ankle to shift so he can walk down a ramp, all he has to do is imagine such movements.
The work was done at the Rehabilitation Institute of Chicago under an $8 million grant from the Army. The armed forces hope to apply findings from such studies to the care of about 1,200 service personnel who have lost a lower limb in Iraq and Afghanistan.
"We want to restore full capabilities" to people who have lost a lower limb, said Levi J. Hargrove, lead author of the new report.
The report describes advances across a wide range of disciplines: in orthopedic and peripheral nerve surgery, neuroscience, and the application of pattern-recognition software to the field of prosthetics.
Weighing just over 10 pounds, the leg has two independent engines powering movement in the ankle and knee. And it bristles with sensors, including an accelerometer and gyroscope, each capable of detecting and measuring movement in three dimensions.
Most prosthetics in use today require the physical turn of a key to transition from one movement to another. But with the robotic leg, those transitions are effortless, Vawter said.
"With this leg, it just flows," said the 32-year-old software engineer, who spends most of his days using a typical prosthetic but travels to Chicago several times a year from his home in Yelm, Wash. "The control system is very intuitive. There isn't anything special I have to do to make it work right."
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