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August 08, 2011
Inspired by young wounded veterans, federally funded labs are creating artificial limbs that may soon blur the distinction between disabled and able-bodied athletes
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August 08, 2011

Prosthetics: Between Man And Machine

Inspired by young wounded veterans, federally funded labs are creating artificial limbs that may soon blur the distinction between disabled and able-bodied athletes

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For a disabled vet, Uncle Sam will pick up the tab for a cutting-edge prosthesis, which can cost more than $40,000. Civilian amputees aren't as fortunate. Many insurance companies limit benefits to one prosthetic per lifetime. "At what point does the technology get to be more accessible and not just about the chosen few?" says SUNY-Cortland sport management professor Ted Fay, who cofounded Northeastern's Disability in Sport Initiative. "Is it just about getting to the moon? Or about having technology filter down to help society?"

Hugh Herr was a world-class climber in 1982 when, stranded for more than three days on Mount Washington in New Hampshire, he suffered frostbite so severe that doctors had to amputate both legs below the knees. He now runs the Biomechatronics Group at MIT's Media Lab, where his mezzanine office overlooks a vast space so clogged with gadgets and fixtures that it resembles the floor of, well, a body shop. Ask him, and Herr will tell you his lab develops "wearable robotic devices" that require "extreme interfaces with the human body."

With $7.2 million in help from the VA, Herr has created a lower-leg prosthetic that essentially normalizes walking for below-the-knee amputees. The iWalk PowerFoot BiOM uses microprocessors, sensors, motors and springs to simulate the Achilles tendon, calf muscles and ankle, with the long-term goal of having each step return as much energy as a biological limb. In Herr's pipeline are devices that go beyond mere body-part replacement to unapologetic augmentation. One, an exoskeleton for runners, features two bows of fiberglass that run up from each toe to a kind of pelvic girdle housing a processor and a set of sensors. Herr hopes that each bow will return so much energy that the user can run with no more exertion than walking. The implications for the able-bodied—for a soldier lugging equipment over rough terrain, say, or a hiker who wants to take in 20 miles' worth of view with 10 miles of effort—are profound. "In the future there'll be a class of transportation devices in which limbs are augmented," says Herr. "And if you're an amputee born today, there's a good chance that, in your 20s or 30s, your athletic performance will be augmented [beyond that of a nonamputee] and your daily life at least normalized."

Herr's lab is hardly alone. Researchers in Sweden do pioneering work on osseointegration, in which prosthetics are bolted directly into the bone of the residual limb rather than attached over the stump by a traditional socket-and-liner system. The Cleveland Clinic is exploring ways to implant bone marrow cells on polymer scaffolding and thereby grow new bone—in a sense, nudging nature to create her own prosthetic. The DOD's Defense Advanced Research Projects Agency (DARPA), a.k.a. the Department of Mad Scientists, is developing two prosthetic arms; one requires surgery and the other does not. A DARPA-funded researcher has FDA approval to begin human trials of a neural-controlled mechanical prosthetic arm that can make more than 20 discrete movements and manipulate individual fingers to perform tasks such as picking up a tennis ball and buttoning a shirt. "I don't know if a bionic arm would hold up to the rigors of competition," says Fay, "but this isn't just incremental. These are giant leaps. We're about to embark on a great theological debate—the Natural Body School versus the Transhumanist School."

A preview of that debate emerged in 2008, when double amputee Oscar Pistorius petitioned to join able-bodied sprinters on South Africa's Olympic team. Born without fibulas, Pistorius became a below-the-knee amputee as an infant and developed into a world-class sprinter on Cheetah carbon-fiber blades. The IAAF, track's international governing body, at first ruled that Cheetahs—which are J-shaped to mimic a sprinter's use of the balls of his feet—returned too much energy with each stride and barred Pistorius from competing in the Beijing Olympics. Herr sat on a panel of experts that helped persuade the Court of Arbitration for Sport to overturn that ruling. Though Pistorius fell .7 of a second short of the Olympic qualifying time in the 400 meters, he went on to dominate the Paralympics, winning golds in three events. (His times in recent races, however, are good enough to qualify him for the world championships in South Korea later this month and for the 2012 Olympics.) A couple of Herr's colleagues on that panel have since dissented from its finding, which only illuminates the knife's edge on which the entire debate teeters.

Even as he defends Pistorius from charges of augmentation, Herr rhapsodizes about how prosthetic technology is on the verge of delivering that very thing. He envisions new sports such as race car cycling and powered running, climbing and swimming. "They'll be so exciting that regular old arms and legs will seem dull," Herr says. "If the Paralympics accept advances in technology, there'll come a time when the Paralympics will be more popular than the Olympics. There'll be these insane human-machine events."

Outside Herr's lab hangs an arresting poster of a glam Aimee Mullins, the former U.S. Paralympic track star. She's striking a pose in a revealing cocktail dress, with Herr kneeling to adjust one of her prosthetic feet, his own artificial limbs visible. "When technology starts to work, it affects people's psychology," he says. "It's sexy, cool and powerful."

As labs like Herr's begin to create limbs and devices that could be controlled in competition, the question arises, Where does the human being end and the robot begin? There's no agreed-upon standard. The Paralympics classification system, designed to make sure multiple amputees don't go up against those whose limbs are intact, is narrowly tailored and more art than science. "Everybody would love to have nice, easy metrics," says Fay, who has classified competitors at three Paralympics, "but we don't. And the more smart prosthetics we have, and the more we can do things like plant regenerative tissue, the more the classification system is exposed."

But both Herr and Fay believe that Transhumanism and Natural Bodyism must eventually be reconciled. If the technology exists to augment performance, surely those devices can be programmed so their assistance nets out within some agreed-upon range of fairness, much as current Paralympic rules require prosthetics to be proportional to residual limbs. Robotics could be set to match the capacity of remaining limbs. Or a device's effectiveness could be dampened the way golf clubs and baseball bats are, so it doesn't exceed a genomic standard. That way champions would still be determined by conditioning, skill and effort. "The only way through this thicket is with more science," Herr says. "Not just engineering, but a more integrated approach. Because in 10 or 15 years people we today regard as having disabilities won't be perceived that way." Indeed, Pistorius indicates how he regards his own condition by declining to park in handicapped spaces.

The thought of elective amputation or "technodoping" rightly sends chills up the spine. But as long as the greatest sprinter in the world could be someone who happens to have been born without fibulas, the sports establishment has some obligation to accommodate him. Since World War II the armed forces have been at the tip of all sorts of spears. They've served as instruments for social progress, from the desegregation of the armed forces in 1948 to this year's ending of "don't ask, don't tell." This time science, not politics, appears poised to collaborate with the military in carrying society over yet another threshold.

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