And when three dozen military veterans participating in a clinical trial used the arm — also known as the "Luke" arm, after the Star Wars character — 90 percent were able to do things they couldn't do with a less-sophisticated artificial limb, like using a key, putting food in their mouths, or zipping up a pair of pants.

For the past eight years, in an old mill building in Manchester, N.H., a team of engineers has been developing what you might call the Tesla of artificial limbs. The DEKA Arm System , about the same size and weight of an adult's arm, can pick up an egg from a carton or a credit card from a desk.


You may have seen the Luke arm on "60 Minutes," a recent Katie Couric segment for Yahoo, or a TED Talk by DEKA founder Dean Kamen in 2007, the year I got an in-person demo of an early prototype. It won the approval of the US Food and Drug Administration in May.

But it just may be too sophisticated to reach the people it can help the most. Medicare and most private insurers are not yet persuaded of the merits of paying for the most advanced prosthetic you can get.

"We're looking at all this new technology," says Rose Bissonette, founder of the New England Amputee Association, "but it's hard for a lot of people just to get a basic prosthetic covered. It's a struggle."

Kamen, also the inventor of the Segway and iBot, a robotic wheelchair, says he was challenged by the Defense Department (which gave the project $40 million) to design a prosthetic arm that would restore as much of the natural limb's capabilities — from opening doors to tying shoes — as possible.


The movements of "Luke" are controlled in two different ways. One is by attaching sensors to remaining muscles on the wearer's body. When the sensors detect electrical activity in the muscles, they send that signal to the Luke arm, which can do things like change its grip or open or close the hand.

The other relies on wireless sensors affixed to the outside of each shoe. Those sensors, explains DEKA engineer Tom Doyon, "detect tilt, much like your smartphone does when you rotate it, basically allowing your foot to act like a joystick," telling the arm to move up, down, left, or right. The arm and attached hand have 800 components.

There is an immense difference in the interpersonal interaction with someone wearing the Luke arm compared to, say, someone using a metal hook. You want to reach out and shake hands with the five-fingered hand that DEKA has designed (it even has plastic fingernails). When someone is wearing a hook, you are not sure what to do.

When I spoke with Kamen late last month, he told me it wasn't yet clear how the Luke arm will reach the market. "The military wants them and they want them now," for injured soldiers, "and we've been looking for manufacturing partners. But you can't get people to agree to make stuff unless someone agrees to buy it."

Kamen says he hopes to get a purchase commitment from the Pentagon or Veterans Administration "that I can wave in front of these big guys, and we'll be off and running." By "big guys," he means large companies that already make medical devices or prosthetics. If he's unable to cajole another company to do that, "yes, we'll make them," he says. "It's my least favorite outcome."


As for the price of the arm, Kamen says it depends on volume: "If you want one, it's $10 million, but two is $5 million, and 100 would be much less." William Hanson, president of Liberating Technologies, a prosthetics maker in Holliston, estimates the price of a Luke arm at "well north of $100,000."

Hanson observes that if amputees are active duty members of the military, or were injured at work, they've got the best chances of getting a high-end artificial limb paid for. But Medicare and private insurers can be reluctant in most other cases.

"Our prosthetics are a fraction of the price of these new systems," Hanson says, "and we still have trouble getting reimbursed."

Other companies are running into the same issues. More than 2 million people have seen the video of Adrianne Haslet-Davis, a survivor of the Boston Marathon bombings, dancing on stage while wearing a prosthetic device from BiOM, a Bedford company founded in 2006 by an MIT professor. The company's $40,000 "powered" ankle (it has microchips, a motor, and battery inside) helps amputees walk with a more normal gait and less effort.

About 1,000 patients use the ankle, says chief executive Charles Carignan. But it is not routinely covered by government or private insurers. The Catch-22 is that to bring the price down, BiOM needs to make more ankles — which would require more people getting covered by insurance.


When someone has lost a limb, Medicare and private insurers would prefer to buy the Kia, not the Tesla, an electric car that sells for $70,000 and up. But Carignan contends that advanced prosthetics can keep people more mobile, healthier, and leading more productive lives. "Unfortunately," he says, "the technology to do that is more expensive, just like new drugs that can extend your life are more expensive."

Will the market support continued innovation in prosthetics, and enable these companies to keep investing in new products? For now, that's a question without an answer.

Scott Kirsner can be reached at kirsner@pobox.com. Follow him on Twitter @ScottKirsner and on betaboston.com.