Bionic prosthetics egging amputees to lose more

Amputations below the knee are helping patients to acquire robotic and fleshlike prosthetics

Five years ago, on a muggy August morning in Hicksville, N.Y., Ann Kornhauser was out walking her golden retriever when bones in her left foot suddenly cracked. Kornhauser, then in her late 50s, soon learned why: Doctors discovered a rare tumor in her foot.

They amputated half of it. The prosthetic foot she received afterwards left her in constant pain; she often cried in her car after trips to the grocery store because she dreaded carrying the bags into the house. Her prosthetist offered a solution. Artificial limbs had greatly improved, he said, and she could benefit from one of the new high-tech models – but it would fit only if her left leg was amputated below the knee.

The idea of losing the rest of her leg, which was healthy enough, seemed preposterous and frightening. But after two years of discomfort, Kornhauser decided to do it. “All my family said was, ‘You’re going to be sitting there without a leg.’ But they didn’t know what I knew,” she said. “I knew it was going to look like a leg and that people ran marathons on them. I knew that I would have a life.”

During a recent interview, the cheerful 63-year-old grandmother pulled up her gray slacks to reveal a prosthetic leg with a fleshlike surface and pedicured toes. Despite its realistic appearance, the leg, with a custom silicone skin and an ankle that can be adjusted for various heel heights, is a marvel of microprocessors, including motion sensors. “I was able to walk again,” she said. “And it looks real.”

Approximately 2 million people in the United States are living with amputations, according to the Amputee Coalition, a national advocacy group. But as artificial limbs are infused with increasingly sophisticated technology, many amputees are making a once-unthinkable choice. Instead of doing everything possible to preserve and live with whatever is left of their limbs, some are opting to amputate more extensively to regain something more akin to normal function. Occasionally this choice is made by someone with a missing hand or arm. But more common are amputations below the knee, which permit patients like Kornhauser to take advantage of robotic and fleshlike prosthetics.

Bionic, or lifelike, prosthetics with custom skins, motors and microchips that replicate natural human motions are edging older models out of the market. The South African runner Oscar Pistorius, a double amputee, has even been accused of having an unfair advantage over competitors because he runs on J-shaped carbon fiber blades.

Amputees “are realising they can do everything that they did before,” said Amy Palmiero-Winters, 39, a celebrated ultramarathon runner who lost her left leg in a motorcycle accident when she was 24. She now works at ‘A Step Ahead,’ a Long Island prosthetics clinic. “They look at people today and see the different things that they’re doing and how it’s more out in the open and accepted.”

Machine beauty

While the loss of a limb remains a medical trauma, many amputees have come to embrace their bionic enhancements. Many “have little desire for the artificial limb to look human,” said Hugh Herr, who heads the biomechatronics research group at the Media Lab at the Massachusetts Institute of Technology, which is developing wearable robotic devices. “They want it to look interesting and have a machine beauty.”

One day in the summer of 2003, David Rozelle, an Army captain, lay in a hospital outside Baghdad, his right foot mangled by a land mine. Doctors amputated it just above his ankle. With an artificial foot, Rozelle , who lives near Boulder, Colo., managed to regain part of his old life. He competed in triathlons and returned to duty in Iraq; he is now a major. But two and a half years after his amputation, he told his surgeon that he wanted 9 inches of his leg removed so that he could benefit from a new below-the-knee prosthesis. His doctor was aghast.

“The medical community is focused completely on salvaging limbs,” said Rozelle, 39.

“There’s actually a disadvantage to having extra limb length, because you can’t fit correctly into prosthetic devices.” He had the operation and now owns several models of sophisticated robotic legs, which he uses for everyday activities and for his favourite sports, like skiing. Many amputees opting for more extensive surgery are athletes like Rozelle hoping to regain active lives.

At 21, Tom White was run over by a truck while riding his motorcycle. His left foot was amputated and then reattached, something he said he ‘begged’ his doctors to do. After 19 operations and two years on crutches, he walked with a limp but went on backpacking trips, ran marathons and generally tried to keep in shape and stay happy.

But as the years went by, the discomfort grew worse. White had his left leg amputated just below the knee to get a sleek carbon-fiber foot. Three years later, he has started training for races again. “I made the decision to have an elective amputation so that I could have a chance to get back to my life,” he said. “It just dawned on me – the technology is amazing, and I would be better off.”

The technology in the newer prosthetics is moving rapidly ahead. Herr, the MIT professor, has founded a startup called iWalk devoted to making next-generation prosthetics. The company’s first product, a bionic foot and ankle, resulted from careful modelling of the muscles, tendons and spinal reflexes used in human walking. The foot can sense the actions of the wearer and the terrain on which the person is walking and adjust accordingly. Its microprocessors help coordinate reflexlike responses to the user’s motions, and its robotics simulate the action of missing calf muscles and Achilles tendons.

According to Herr, an amputee using the foot uses the same amount of energy while walking as someone with biological limbs – a first for a prosthesis. But it is not cheap – about $70,000. While insurers will pay for basic protheses, they generally do not pay for high-end artificial limbs like these.

And these devices are likely to become more sophisticated. At Johns Hopkins University, researchers financed by the Defence Advanced Research Projects Agency have been working to create new prosthetics for soldiers with upper extremity amputations. Until recently, most of them wore only a basic hook.

The goal is to build artificial limbs that resemble human arms in dexterity, strength, size and weight – and that veterans one day may control with their brains. The scientists plan to insert a small array of electrodes into the cortex, the brain’s top layer, or into peripheral nerves. The hope is that by capturing these nerve signals and transmitting them to an artificial limb, thought can be turned into motion. Hopkins researchers are even planning to test a limb that might allow amputees to feel pressure, heat and cold.

Intelligent artificial limbs like these are still years away, and it will be a long time before the Bionic Man or Woman is a reality. But the improving technology already has provided amputees with one invaluable benefit. “I don’t feel ugly anymore,” White said. “I feel like a normal guy.”