As test pilot, MTSU student works out bugs in robotic leg
2:55 AM, Aug. 14, 2011
Craig Hutto’s leg was mangled by a 6-foot-long bull shark with a stubborn streak.
Not long before the attack, he’d heard about a Louisiana girl who died from a shark attack just 100 miles away from Cape San Blas, Fla., where Hutto, then 16, and his family were vacationing. But he just wanted to go fishing, so he was standing in murky water when he felt the first bump, then the agonizing bite. The shark seemed impervious as Hutto’s brother pounded away at its nose with a rod and reel.
Hours later, Hutto lay in a Panama City hospital bed, pleading that his mangled right leg be saved. No leg meant no varsity basketball. No spring baseball. No independence.
But doctors ultimately ruled in favor of life over his lifeless limb, amputating five inches above the knee.
Six years later, Hutto’s life is different from the one he planned. But he feels closer to his family. He’s a few months shy of his bachelor’s degree in nursing from Middle Tennessee State University — a path he never would have taken without that shark’s intervention. And he’s serving as test pilot for a robotic leg being developed at Vanderbilt University, his effort to make life better for the nation’s rising number of amputees.
“I was planning on doing computer science when I went to college,” he said. “Then this happened to me, and I realized these people saved my life and I have to do something to pay them back.”
As a lab assistant at Vanderbilt, Hutto, now 23, works with professor of mechanical engineering Michael Goldfarb and his team of researchers. The leg he’s testing is the first of its kind. It makes it easier for Hutto to walk up slopes and stairs because a computer chip activates an electronic calf muscle.
The leg also makes it easier for Hutto to stay standing because it responds to sudden shifts in motion the way non-mechanized prostheses don’t.
“When it goes on the market, I can tell myself I experienced the falls and mishaps to get it where it is today,” he said.
The robotic leg weighs about 9 pounds and features programmable software that responds to Hutto’s movement. It can tell when he’s trying to sit or stand, or when he needs extra help to walk up stairs. He has been testing the leg for four years, weighs in on the leg’s functionality and gives researchers feedback on any issues that may arise.
Hutto also reviews other studies and literature about prostheses for the team.
Up to the challenge
Vanderbilt researchers estimate there are 620,000 people in the United States with a major lower limb amputation, and about half are above the knee, similar to Hutto’s. Because of the prevalence of diabetes, that number is projected to double in the next 30 years, Goldfarb said.
He’s been working on the robotic leg since 2005, but his team is months from a finished product. It’s licensed to a company and should be on the market within a few years.
Goldfarb said it will be one of the most sophisticated devices on the market.
“We want to develop technology that improves quality of life for disabled persons,” he said. “No one had ever done this before, so it was unclear whether or not you could build a leg that had enough power and was light enough to replace the biomechanics of the knee and ankle.”
With his regular prosthetic leg, Hutto must exert about 60 percent more energy than a healthy person to walk. Goldfarb said the new leg will decrease the metabolic effort its user needs to walk, increase the rate he can walk, and lessen falls and injury.
Studies show that amputees fall at the same rate as elderly people because of the lack of reflexes and must seek medical attention as a result.
“We wanted someone that would not mind the physical challenge and was tolerant of a lot of bugs in the system,” Goldfarb said. “It’s so interactive that you have to be an amputee to test it. He’s uncovered countless number of bugs and had to have a lot of patience. Craig is really like a test pilot.”
Saved for purpose
Hutto’s outlook is much brighter now than on June 27, 2005, when a shark’s teeth changed his life. Within three months, he went from a wheelchair to crutches to a prosthetic leg. His junior year, he sat on the sideline through every basketball practice and game.
Before he left the hospital, depression began to set in. The advice of his brother Brian, who had grabbed Hutto and swum to shore while the shark was still gnawing at his leg, made the difference.
“He told me I needed to quit being a baby and that I had gone through the worst and needed to move on,” Hutto said. “That’s when I realized I couldn’t change anything. I know people don’t mean it, but I get mad when they feel sorry for me because it makes me think what I used to be like.”
There are still challenges. He has a slight limp and must examine his leg daily because the slightest sore left unattended could ultimately prevent him from walking. He has 90 percent functionality in his hands. And two fingers are still numb after the shark bit at his hands as Hutto struggled to pry it from his leg.
“I hated this (prosthetic) leg at first, mainly because I’d never felt something like that before,” he said.
“I just had this big weight hanging off my body, and I couldn’t see how I was going to be able to walk with this.
“Now, I refuse not to wear my leg even one day because that’s just a sense of my mobility gone out the door.”
He doesn’t get into the water much because it means shedding the leg, but he doesn’t fear the ocean.
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