Bionic leg makes amputee faster on his feet

January 24, 2012 By Miles O'Brien and Ann Kellan

Craig Hutto considers himself part bionic man. In 2005, doctors amputated his leg after a shark attacked him during a fishing trip off the Florida Gulf Coast.

"I was 16 years old at the time," recalls Hutto. "My brother heard me yell: 'What was that?' He saw something take me under; he saw the back fin of the shark. There was so much and so much flesh gone that it was just irreparable."

The video will load shortly

Two years later and game for a challenge, Hutto became the test pilot for a unique and powerful new prosthetic leg being developed by mechanical engineer Michael Goldfarb and his team at Vanderbilt University. The effort was kick-started by a grant from the National Science Foundation (NSF).

"We were able to develop an early prototype that demonstrated that you could have a leg that was light enough and could deliver biomechanical levels of torque and power," says Goldfarb.

Version 1.0 evolved into a more streamlined version 2.0, which is computer controlled, with advanced range of motion in the joints. Version 2.0 was funded by the National Institute of and at the National Institutes of Health.

"This is a battery that powers everything," explains Goldfarb, holding up the latest version and pointing to the various components. "You have a motor that drives the knee joint, another motor that drives the . There is a whole computer board that essentially tells the motors what to do with the joints."

In Goldfarb's lab, Hutto straps on the prosthetic and "walks the walk" on a treadmill--each step recorded by an array of cameras to help engineers improve the mechanics, electronics and software.

Brian Lawson, a and member of Goldfarb's team, says what makes this prosthetic stand out is the on-board computer. "What I think makes people think that it's bionic is the computing capability that infers what the user is trying to do and works synergistically with the user to provide the torque at the right time."

The is designed to respond to cues from the wearer. For example, when Hutto goes from walking to climbing stairs, he gives a signal and the bionic leg responds. "I kind of kick my thigh back just a little bit," says Hutto, "and just that little movement tells it, 'Hey you're about to walk upstairs,' and it switches mode into the stair ascent."

To reduce the risk of injury, Goldfarb's team has intentionally programmed a slight delay into the leg's computer to make sure the wearer and the prosthetic stay in perfect step with each other, and to make walking easier. "The leg can move with you," says Goldfarb.

Hutto confirms it takes less effort to walk compared to the prosthetic he currently wears. "With my leg, it's harder because it's always a step behind. I'm having to use my hip to swing my leg through, whereas the Vanderbilt Powered Prosthetic, when it toes off, the power swings the leg through and so I'm not having to use my hip to swing it through."

Goldfarb says after years of work, they have sold their technology to a major prosthetic manufacturer. "We'll know in the next few years if these are going to come onto the market and really gain a lot of traction," he says.

Meanwhile, Hutto, inspired by the three nurses who saved him from bleeding to death, is studying to become a nurse and looking forward to one day walking tall on the that he helped make a reality.

Explore further: Bionic leg undergoing clinical trials

Related Stories

Bionic leg undergoing clinical trials

April 22, 2011
(Medical Xpress) -- A "bionic" leg designed for people who have lost a lower leg is undergoing clinical trials sponsored by the US Army. The researchers hope the leg will be able to learn the patient's nerve signal patterns ...

Ohio State surgeons rebuild pelvis of cancer patient

May 5, 2011
In a rare and medically remarkable operation, a multi-disciplinary team of surgeons at the Ohio State University Comprehensive Cancer Center – Arthur G. James Cancer Hospital and Richard J. Solove Research Institute ...

Recommended for you

Want to win at sports? Take a cue from these mighty mice

July 20, 2017
As student athletes hit training fields this summer to gain the competitive edge, a new study shows how the experiences of a tiny mouse can put them on the path to winning.

'Smart' robot technology could give stroke rehab a boost

July 19, 2017
Scientists say they have developed a "smart" robotic harness that might make it easier for people to learn to walk again after a stroke or spinal cord injury.

Engineered liver tissue expands after transplant

July 19, 2017
Many diseases, including cirrhosis and hepatitis, can lead to liver failure. More than 17,000 Americans suffering from these diseases are now waiting for liver transplants, but significantly fewer livers are available.

Lunatic Fringe gene plays key role in the renewable brain

July 19, 2017
The discovery that the brain can generate new cells - about 700 new neurons each day - has triggered investigations to uncover how this process is regulated. Researchers at Baylor College of Medicine and Jan and Dan Duncan ...

New animal models for hepatitis C could pave the way for a vaccine

July 19, 2017
They say that an ounce of prevention is worth a pound of cure. In the case of hepatitis C—a disease that affects nearly 71 million people worldwide, causing cirrhosis and liver cancer if left untreated—it might be worth ...

Omega-3 fatty acids fight inflammation via cannabinoids

July 18, 2017
Chemical compounds called cannabinoids are found in marijuana and also are produced naturally in the body from omega-3 fatty acids. A well-known cannabinoid in marijuana, tetrahydrocannabinol, is responsible for some of its ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.