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PROSTHETICS: BETWEEN MAN AND MACHINE

Aug. 08, 2011
Aug. 08, 2011

Table of Contents
Aug. 8, 2011

LEADING OFF
Inside: THE WEEK IN SPORTS
SPORTS MEDICINE
Departments

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

Examine what military tacticians call the tip of the spear—the leading force in combat—and you're liable to find 1st Lieut. Melissa Stockwell, U.S. Army (ret.). It's a role she has embraced since April 2004, when a roadside bomb in Baghdad blasted off all but six inches of her left leg and made her the first female American amputee of the Iraq war. Four years later, as a swimmer, she became the first veteran of that conflict to qualify for the Paralympic Games. Now, having just passed her board exams to become a certified prosthetist, she figures to be a very busy woman, spearheading yet another movement.

This is an article from the Aug. 8, 2011 issue

Stockwell leads a generation of disabled veterans of the Afghanistan and Iraq wars who are becoming elite athletes. The combined number of vets on the U.S. teams at the 2008 Summer and '10 Winter Paralympics jumped to 21 from a total of seven at the previous Games, in Athens and Turin. At next year's London Paralympics, U.S. officials estimate that 20% of Team USA will be composed of veterans. That infusion has helped the U.S. creep up in the medal count, from fifth to fourth to third, over the last three Summer Paralympics.

Stockwell's cohort stands poised to deliver more than medals, however. It's the vanguard of a revolution in attitudes toward people with disabilities. "My prosthetic is definitely a badge of honor," says Stockwell. "I'll walk around in shorts and flip-flops." At the same time, tens of millions of dollars from the departments of Defense and Veterans Affairs are funding advances in prosthetic technology so profound that they raise essential questions about what it means to be human.

To meet the growing demand from wounded warriors, the U.S. Olympic Committee is disbursing $7.5 million donated by the VA to help not only veterans but also active-duty soldiers. Since 2004 U.S. Paralympics has been hosting military sports camps to enhance the rehabilitation of veterans and active service members with disabilities. Meanwhile the USOC and the DOD are ramping up events such as the Warrior Games, which were staged for the second time, in May, in Colorado Springs, with 200 physically impaired vets and soldiers competing in seven sports.

People who work with them agree that soldiers are athletes to begin with, and injured ones are like any jock aching to get off the DL. "It's amazing how many say to me, 'I'm going to be your best patient,'" says Peter Harsch, director of prosthetics at the San Diego Naval Medical Center. "Their driving force is, Number 1, to get back to their division or squad. But then, this is a military where everyone had a choice whether to go into it." (As many as 18% of amputees return to active duty, most of them to noncombat jobs.)

When Stockwell arrived at Walter Reed Army Medical Center in Washington, D.C., her very survival still hung in the balance. After 15 operations, 20 blood transfusions and a series of infections, she was turned over to Walter Reed's therapists. "I looked around and saw people missing two, three and four limbs, people with traumatic brain injury and lost eyesight," says Stockwell, who had been a rower and diver at Colorado. "It motivates and inspires." After one year at Walter Reed and two more dedicated to swimming, she was still a long shot at the 2008 U.S. Paralympic trials, yet she lopped a staggering 17 seconds off her previous best in the 400-meter freestyle to make the team. (She did not medal in Beijing but carried the U.S. flag at the closing ceremonies.) Now a paratriathlete, Stockwell won gold in the severe leg impairment category last September at the world championships in Budapest. "I've done more with one leg," she says, "than I ever would have done with two."

That's a tribute not only to Stockwell's grit but also to Walter Reed. There, 30 physical and occupational therapists at the Military Advanced Training Center (MATC) use state-of-the-art equipment such as the Computer Assisted Rehabilitation Environment (CAREN)—a virtual-reality room that simulates real-world conditions and that Harvey Naranjo, coordinator of the MATC's adaptive sports program, likens to "a Wii on crack"—and a diagnostic studio in which 35 cameras and six force-measuring plates feed data to computers that instantly detect when a prosthesis needs the slightest adjustment. More than anything else, the MATC, which is scheduled to move this month to Bethesda, Md., is a hothouse where wounded warriors challenge one another to reclaim as much as possible from the lives they once knew.

As soon as patients build up enough strength and coordination, the therapists introduce competitive sports. "With this type of population you can only do cones and weights for so long," says Naranjo. "The discipline to get up in the morning and work out is already embedded. Prior to their injuries they were all physically fit, so they'll recover quickly if you get them going fast."

Naranjo's unit prides itself on sending athletes to iconic marathons for the able-bodied such as the New York City Marathon and New Mexico's Bataan Memorial Death March. In May 2010 a Walter Reed team, Missing Parts in Action, competed in Washington State's Ski to Sea, a 100-mile relay race comprising seven sports: cross-country skiing, downhill skiing or snowboarding, running, road biking, canoeing, mountain biking and sea kayaking.

In February, only two weeks after Walter Reed sent a group of adaptive snowboarders to try para--snowboard cross at Utah Olympic Park in Park City, one of them—former Army Capt. Nathan Wayne Waldon, an above-the-knee amputee—placed 18th at the World Snowboard Federation World Cup, which stages a special competition for para-athletes. Adaptive snowboarding might be a medal sport at the 2014 Paralympic Winter Games, and Waldon hopes his busy nonathletic life (he works in program management for General Dynamics and takes graduate business courses at night at Georgetown) will permit him to participate. "All they want to do is get better, to go out and kick some butt, and we give them the tools to do it," Naranjo says. "In previous wars, it was, Here's your prosthesis, have a good life. These guys have pushed the technology. Things I thought were incredible 10 years ago are nothing compared to what I'm seeing now."

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.

"ALL THEY WANT TO DO IS GET BETTER, TO GO OUT AND KICK SOME BUTT, AND WE GIVE THEM THE TOOLS TO DO IT," NARANJO SAYS OF WOUNDED WARRIORS.

MYTH BUSTER

NO. 2: DRINK A LOT OF WATER

Traditional guidelines suggest that athletes who lose more than 2% of their bodyweight in competition are dehydrated, but scientists have found that elite marathoners lose up to 10%. "It's just not possible to become dehydrated to the point of risk or even impaired performance unless you are denied access to fluids for many hours or even days," says Ross Tucker, a South African exercise physiologist. The safest way to drink during activity is ad libitum—whenever you feel like it.

NEW AND IMPROVED

This light, durable prosthetic of the future, based largely on the SPARKy leg developed by researchers at Arizona State, will be closer than ever to a human limb and contains elements that will someday enhance athletic prostheses

1 THIGH HIGH

Above-the-knee amputees need more engineered aid than their below-the-knee counterparts, so they often compete in a different Paralympic class.

2 OSSEOINTEGRATION

Prosthetic limbs that connect directly to the bone—replacing the current socket-and-liner standard—could be the wave of the future for Paralympic athletes.

3 MATERIAL DIFFERENCE

A forward shaft simulates the lower leg, and posterior shafts provide some stability. Carbon composites are lighter than intact limbs and can return up to 93% of energy stored with each stride.

4 RATE OF RETURN

A flexible blade works with motorized springs in the ankle, though the hips must generate much more energy than those of able-bodied athletes.

ILLUSTRATIONILLUSTRATION BY BRYAN CHRISTIEPHOTOSIMON BRUTYTHE ATHLETE Stockwell, who swam for the U.S. at the 2008 Paralympics only four years after becoming the first U.S. female amputee of the Iraq war—she lost her leg in a bomb blast in Baghdad—will compete in the paratriathlon nationals in New York City on Sunday.PHOTOSIMON BRUTYTHE VISIONARY Herr says he develops "wearable robotic devices" that can not only replace body parts but also augment athletic performance, which will someday lead to a new range of sports "so exciting that regular old arms and legs will seem dull."