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New 'bionic' leg that moves like natural leg developed

August 19, 2011 - Washington

A new lower-limb prosthetic has been developed that allows amputees to walk without the leg-dragging gait characteristic of conventional artificial legs.

The device developed at Vanderbilt University uses the latest advances in computer, sensor, electric motor and battery technology to give it bionic capabilities: It is the first prosthetic with powered knee and ankle joints that operate in unison.

It comes equipped with sensors that monitor its user's motion. It has microprocessors programmed to use this data to predict what the person is trying to do and operate the device in ways that facilitate these movements.

"When it's working, it's totally different from my current prosthetic," said Craig Hutto, the 23-year-old amputee who has been testing the leg for several years.

"A passive leg is always a step behind me. The Vanderbilt leg is only a split-second behind," added Hutto.

The bionic leg is the result of a seven-year research effort at the Vanderbilt Center for Intelligent Mechatronics, directed by Michael Goldfarb, the H. Fort Flowers Professor of Mechanical Engineering.

"With our latest model, we have validated our hypothesis that the right technology was available to make a lower-limb prosthetic with powered knee and ankle joints," said Goldfarb.

"Our device illustrates the progress we are making at integrating man and machine," added Goldfarb.

The Vanderbilt prosthesis is designed for daily life. It makes it substantially easier for an amputee to walk, sit, stand, and go up and down stairs and ramps. Studies have shown that users equipped with the device naturally walk 25 percent faster on level surfaces than when they use passive lower-limb prosthetics. That is because it takes users 30 to 40 percent less of their own energy to operate.


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