Rosen considers himself a futurist. He thinks in terms of "engineering medicine," not medical engineering. In the 1980s, he tried to coax nerve fibers to grow through a computer chip. "A nerve is a cable with thousands and thousands of wires," he explains. A surgeon can stitch the cable together, but the individual wires are too small to sew—and, left on their own, they usually hook up wrong. "We wanted to create a micro-switchboard to help them reconnect," Rosen says. He didn't succeed in teaching nerves to talk to hardware, but his basic idea was sound. Recently, a company called Cyberkinetics (with which Rosen has no connection) developed a robotic arm that patients with spinal-cord injuries can move just by thinking about it.

Rosen's early experiments with "wetware"—an interface between software and living tissue—led him into virtual reality. He has helped develop simulators (based on real patients' CAT scans) that allow a surgeon to practice difficult techniques, such as fixing an abdominal aortic aneurysm through a catheter. He is also collaborating on a robot to be used to defuse bombs and clean up hazardous waste. What's the connection between a "hazbot" and virtual surgery? The software for the hand controls: the hazbot will need to have very delicate hands to be able to pick up a bomb without detonating it. Likewise, says Rosen, "when I'm operating on a virtual head, I need a really good haptic device, a simulation with really good feedback, so that I can tell how much force I'm applying. No surgical simulation has that yet."

In 1993, Rosen served on a National Academy of Sciences committee that forecast virtual reality's effects on health care. His insights on human-machine interfaces brought him to the attention of the Department of Defense (DoD), which has since sought his views on virtual reality, future warfare, bioterrorism, and polytrauma. "As a plastic surgeon," says Rosen, "you're often presented with problems that have no solution, with people . . . who have so many damaged parts that there's little or no way to solve their problems. That's what we mean by catastrophic polytrauma." For example, he can fashion a new nose but can't restore a soldier's sense of smell. He can reconstruct an eye socket but can't restore sight. Nor can surgery alone bring hope to a soldier missing a face, arms, and legs.

In 2004, Rosen was asked to give a grand

Rosen's plastic surgery practice gets him thinking about the relationship between soul and skin.

rounds on polytrauma at Walter Reed Army Medical Center in Washington, D.C. Could he, as a futurist, envision a system that would allow such patients to live independent lives? And not in 10 or 20 years, but tomorrow?

Two years later, in December 2006, 100 experts in medicine, engineering, and robotics met at a polytrauma conference that Rosen organized at Dartmouth. "They certainly sacrificed for the country, for freedom, for all the things we believe in," Rosen says of the soldiers whose plight prompted the gathering. "Why shouldn't we do as much as possible?" At least 300 soldiers suffering from massive multiple injuries, most of them wounded in Iraq, remain hospitalized today.

Thinking futuristically, Rosen believes the answer to polytrauma is regeneration. "A salamander can regenerate an arm in 42 days. So somewhere in your genome that ability still exists, to regenerate a whole limb. We just have to find it and turn it on," he says. "We'll be doing that in 20 to 50 years—or sooner."

Actually, he'd prefer to prevent polytrauma. He can envision a virtual reality simulator of a soldier's entire career—training, battle, injury, treatment. "You'd decide all along the line how to maximize performance and inhibit injury," he explains. For instance, the simulator could lead to innovations in armor. "The better you know the weapons," Rosen says, "the better you understand the whole relationship between medicine and war."

The short-term solution, he believes, is to replace the missing parts with machines. "Ambroise Paré did that already in the 16th century," Rosen says. "He made a prosthetic arm out of armor—shining armor—with springs in it, and attached it with leather straps. But what do you do if you're a soldier who's missing one arm and two legs? You get an exoskeleton. It provides a frame you can be in."

Engineers in Utah, with DoD funding, have in fact created a wearable exoskeleton that senses and enhances the wearer's movements. The wearer simply runs or jumps or picks up a wounded comrade, and the robotic exoskeleton increases the person's speed and strength to superhuman levels. Rosen, who wasn't involved in the device's initial design, wants to push the concept further. As a member of the Defense Science Board, he is now lobbying for the DoD to adapt this prototype "bodybot," originally meant for battlefield situations, so that it can also help the limbless walk and the blind see.

But will people accept someone encased in an exoskeleton as human? "First people have to believe that the solution works," says Rosen. "Then the users have to believe it's a positive thing, not a negative thing"—the same problem faced by Civil War amputees. "You also have to consider economics. It can cost $75,000 for one robotic arm. Can you imagine the cost of the whole suit? So we can't, economically, apply this technology just to soldiers," Rosen says. "But we could adapt it for children with cerebral palsy. We could also adapt it for fragile elderly people so that they can continue to be independent. It would be cost-effective if we had a connected health-care system that considered the whole issue of independence for an older person and the expense of long-term care." (Rosen discusses more of his ideas in a multimedia Q&A.)

The idea of restructuring the U.S. health-care system, while making a whole-body prosthesis practical and socially acceptable, might seem more like science fiction than medicine. But Rosen approaches the task with the same tenacious optimism as when he travels to an African village to operate on a child without a face.

"It's just an attitude," he explains. "Someone says to me, 'You can't get there.' I say, 'Well, maybe you can't, but I can.'"