The Boston Arm

Boston has a history of leading innovation in prosthetics.


Will-Powered: The Boston Arm was a joint project of MIT, Harvard, Mass General, and Liberty Mutual Insurance Company. Among the scientists who worked on the prototype, one was a missile engineer who was used to cramming technology into small, cylindrical spaces, said T. Walley Williams, one of the arm’s designers. A descendant of the arm is still built and sold at Liberating Technologies, in Holliston. (Photograph by Bruce Peterson)

In 1968, when Boston-based Liberty Mutual Insurance Company debuted its state-of-the-art prosthetic arm at Massachusetts General Hospital, newspapers across the country hailed the dawn of the cyborg. The “psychic robot limb” moved “just by thinking,” reporters gushed. In a way, they were right: A motor in the elbow whirred into action when sensors picked up tiny electrical charges in the wearer’s arm. They called it the Boston Arm, and it seemed to work like magic.

Boston—gifted with both world-class hospitals and top-flight universities—has remained a hub of prosthetics innovation for decades.

“In our economy we don’t have a copper mine or an oil well,” says Deborah Douglas, a curator at the MIT Museum, where prototypes of the original Boston Arm are on display. “We extract things from ideas, and that comes from this cross-fertilization of all these smart people in one place.”

For the victims of the Boston Marathon bombings, the prosthetics landscape is very different from what it was back in 1968. Mere miles from the blast site, engineers like MIT’s Hugh Herr are building cutting-edge limbs equipped with multiple computers, motors, and sensors.

But in crucial ways, the prosthetics industry isn’t like Boston’s other high-tech businesses. For one thing, the market for its products is small: Amputees make up less than one percent of the population, so research is driven by other incentives. In the 1960s, Liberty Mutual—then one of the biggest workers’-compensation insurers in the country—developed the Boston Arm because it was more efficient to send maimed policyholders back to work than it was to pay their long-term disability costs.

Today, the leading work in prosthetics is being driven by the Department of Defense, which funds research and development at local companies and universities. Disabled veterans get access to high-tech devices, enabling them to return to the workforce or, in some cases, to the battlefield.

Unlike other types of technology, prosthetics are competing with a prototype that’s hard to match: the human body. “You think an arm is an arm,” says Sandra Tanenbaum, the Ohio State University professor who studied the Boston Arm for her Ph.D. “But actually arms are lots of things, and you can only reproduce a given number of them in technology.”