Amputees put Power Knee to test



Amputees put Power Knee to test


TAMPA - One man was an Army Ranger chasing after Manuel Noriega in Panama when he was shot five times and lost his right leg.

Another lost his left leg to bone cancer. A third had his leg amputated above the knee after he got stuck on a conveyor belt at a chicken feed plant.

The amputees have different stories, but this in common: They are among a few dozen people in the world who use a cutting-edge, electric-powered artificial limb that employs Bluetooth technology to help the leg mimic natural movement.

And they were all recently at the University of South Florida, helping researchers try to determine if the artificial knee mimics real leg movement well enough to warrant broader use.

The Ossur Power Knee, manufactured in Iceland, propels users forward when walking and lifts them out of chairs and up stairs.

University of South Florida assistant professor Jason Highsmith is studying how well the knee synchronizes movement with the remaining leg.

Backed by a $1 million grant from the Department of Education, he'll see if the knee mimics the shortening action of the quadriceps muscles that typically lift a sound leg. Ease of movement for above-the-knee amputees could lead to mass production of the high-powered prosthetic, which is now used by just 40 people worldwide.

Usually, amputees shift to their able-bodied sides when rising. Over time those muscles compensate, becoming more developed while the side not being used atrophies, Highsmith said.

"They are muscularly imbalanced," he said. "The idea is that by adding some of that power back into the prosthesis, we can balance the muscles and spare the joints."

It works like this: Pressure sensors in the shoe of the able-bodied side send signals to the prosthetic knee by Bluetooth technology that is strapped to the ankle.

Jim Beeson, 57, has been wearing the knee for a year. He lost his leg in a work accident at a steel company in 1985. But he couldn't get comfortable with prosthetics, so he used a wheelchair for 12 years.

A year ago, he told his doctor he wanted to walk again.

She told him about the Power Knee. Now a police officer, he couldn't be happier.

"I go fishing with my grandchildren, shopping with the wife, whereas before, I just stayed home," he said.

At USF last week , the amputees stood on scales to measure pressure as they stood while attached to sensors monitoring muscle contraction and joint motion. They sat and stood, again and again.

The artificial knees need some adjustment to get them to move naturally.

Sometimes the knee propelled the foot too far, causing it to kick out when a user sat down. Other times, it has been known to lift too forcefully as the person tries to stand.

Once finished, Simon Bouchard detached his artificial foot with a tool he doesn't leave home without, and set it at a sharper angle. Bouchard, 30, lost his leg to cancer in 2002.

Bouchard, who lives in Quebec, says he was the first person to use the knee in 2004.

"Other legs in the market use your energy, but this one has its own power. It's important to show what it can do because one day insurance will pay for this."

It's not perfect yet, said Bill Dunham, 39, from Arkansas.

At 10 pounds, it's heavier than the 3.5-pound C-leg he prefers to wear. Also, the Power Knee's battery doesn't last all day, Dunham said.

He spun his leg upside down to show the stamp: human bionic, which Webster defines as performance enhanced by electronic or electromechanical devices.

Experts say technology to improve life for amputees is growing as improved medical care brings more people back from Iraq without limbs.

The Power Knee costs about $120,000, compared with $20,000 for standard prostheses, said Highsmith, who also designed and built a prosthetic hand for kayakers from a steel pipe last year.

He plans to publish the results of the knee study early in 2008 in a scientific journal.

"Unfortunately these people often become sedentary," Highsmith said. "This may keep them up and moving longer."
That is incredible to hear about. I am certain that when the manufacturing capacity for such devices is improved that the cost will come down along with it.
That is incredible to hear about. I am certain that when the manufacturing capacity for such devices is improved that the cost will come down along with it.

I hope so, that is bloody expensive.
Great product though!