When VA began examining an experimental prosthetic arm with reputedly far greater capabilities than anything now available Downs volunteered as a subject, but he was not expecting anything remarkable. "I was skeptical at first," he said. "I couldn't believe it would work as well as they said it would."
Instead, Downs found himself brought to tears when the prosthetic arm allowed him to smoothly bring a water bottle to his mouth and drink.
"For the first time in 41 years I was able to grasp with my left hand," Downs said. "I wasn't expecting that. I'm so used to being an amputee, it was an emotional thing."
Last week, VA announced the start of a three-year clinical trial that represents the first large-scale testing of the arm, a critical step before it can be made widely available. The first patient was fitted with an arm in April.
If the trial is successful, the robotic arm could restore a measure of freedom for some injured veterans of the wars in Iraq and Afghanistan, a significantly higher proportion of whom have lost arms than in previous conflicts. "When you lose upper extremity, you lose your independence," Downs said.
The device was developed by Deka Research and Development, the New Hampshire company whose founder, Dean Kamen, invented the Segway and various medical devices. Deka undertook the project 30 months ago as part of a $100 million program to revolutionize prosthetics sponsored by the Pentagon's Defense Advanced Research Projects Agency (DARPA).
The robotic arm, nicknamed the "Luke arm" after the artificial arm worn by Luke Skywalker in the "Star Wars" films, allows those who have lost a limb up to their shoulder joint to perform movements while reaching over their head, a previously impossible maneuver for people with a prosthetic arm.
"It's actually light years closer to a real arm," said Joel Kupersmith, VA's chief research and development officer.
About 22 percent of the 820 American troops injured in Iraq or Afghanistan who have suffered major amputation have lost arms, while the comparable figure in Vietnam was only about 4 percent, according to Downs.
The reason is ever-improving medical treatment in the field and speedy evacuations that has saved the lives of many grievously injured troops in Iraq and Afghanistan. "In Vietnam, the blast that would blow off your arm was usually able to damage your torso so much it would kill you," Downs said.
The technology developed for upper-extremity prosthetic devices has trailed far behind that used for artificial legs. "Work on arms is more difficult," Kupersmith said. "The movement is more refined."
The DARPA project has been aimed at bringing arm prosthetics into the 21st century. "DARPA has undertaken the monumental task of fulfilling our pact to our soldiers by embarking on an effort to provide fully integrated limb replacements that enable individuals with upper body limb loss to perform tasks with the strength and dexterity of the natural limb," Army Col. Geoffrey Ling, manager of the prosthetics program for DARPA, said in a news release.
The VA study is being conducted in conjunction with DARPA under the direction of Linda Resnik at the VA Medical Center in Providence, R.I. Veterans fitted with the arm will provide feedback to help engineers refine the prototype in preparation for commercializing the arm and making it available through the VA health-care system.
Users control the arm via an array of sensors embedded in a shoe, maneuvering it by putting pressure on different parts of the foot. Wires relay the signals to the arm, but future versions will be wireless.
The arm can also be adapted to work with other control systems, including myoelectric switches, which are wired to residual nerves and muscles in the upper body and can respond to movement impulses from the brain, shoulder joysticks or other inputs.
Downs sometimes visits Walter Reed Army Medical Center to encourage soldiers who have lost arms, but he said he has tried not to oversell the Deka arm's potential. "It's important not to get expectations too high when things are at this stage," he said.
Still, interest in the arm is growing. It was featured in a recent "60 Minutes" episode on CBS, and last week at the VA hospital in New York City, Downs participated in a briefing during which a veteran demonstrated the arm to Britain's Prince Harry.
"The soldiers do ask me about it, what I think about it," Downs said. "They're anxious to try it."