BiOM bionic ankle gives amputees natural movement

Essdras M Suarez/Globe Staff

Brian Frasure, BiOM’s director of clinical services, and Timothy McCarthy, its fomer CEO, hope to make the company’s prosthetics more broadly available. At $52,000, they aren’t cheap. But “neither is a hip replacement,” McCarthy says.

By Michael B. Farrell Globe Staff 

When Brian Frasure enters the room, it’s virtually impossible to tell that he’s an amputee.

“Most amputees walk with a limp, and that’s because of the prosthesis,” said Frasure, who lost the lower part of his left leg in college after miscalculating a leap onto a moving freight train.


Today, Frasure walks as if that accident never happened. He wears a bionic ankle made by BiOM, a small Bedford company performing some of the most cutting edge work in the field of artificial limbs.

The BiOM ankle is programmed to replicate all the natural functionality of the foot and ankle. It gives Frasure the sort of flexibility and movement he took for granted before his accident.

“It kind of felt like I had my calf muscles again,” Frasure said about the first time he wore the BiOM three years ago. 

Prosthetic technology has made tremendous gains in recent years. As a result of the Iraq and Afghanistan wars, the Pentagon invested millions of dollars to help spur those developments. One of the key figures driving much of that innovation is Hugh Herr, who leads the Biomechatronics research group at the Massachusetts Institute of Technology.

Herr is an amputee himself. He lost both of his lower legs after a mountain climbing accident in 1982 and has devoted much of his professional career to designing better ankles for amputees. In 2006, Herr created a company called iWalk to make a sophisticated bionic ankle that he developed with his group inside the MIT Media Lab.


Last year, iWalk changed its name to BiOM and aimed to expand the customer base for its ankle. So far, about half of the 1,000 people who have been fitted with the BiOM ankle are veterans wounded in Iraq or Afghanistan.

BiOM wants the Centers for Medicare and Medicaid Service to cover the cost of its bionic ankle so seniors and other Medicare patients can receive the benefits of bionic technology. For that to happen, BiOM must convince the government that its ankle will substantially improve lives and help reduce other medical costs.

At a price of $52,000, the ankle isn’t cheap. “Neither is a hip replacement,” argued Timothy McCarthy, the former chief executive of BiOM. “We will save them money over time.”

Because the BiOM ankle helps propel wearers forward as they walk, it does not produce some of the strain caused by a traditional prosthesis. Its sleek metal casing houses a complex array of sensors and microprocessors controlling a carbon spring that acts as the foot. And the ankle comes with enough computing power to be custom-programmed for every user.

“The beauty of what Hugh’s done is to replicate muscle tendon function,” said McCarthy. “That’s the mystery.”

Herr doesn’t intend to stop with the ankle. He wants to use the core technology to build bionic limbs and other joints.


A dramatic display of the BiOM’s potential came during a recent TED conference talk, at which Herr spoke about the promise of bionics. At the end of his talk, he was joined on stage by Adrianne Haslet-Davis, a ballroom dancer who lost the lower part of her left leg in the Boston Marathon bombings. Wearing a customized BiOM ankle, she danced in public for the first time since she lost her leg.

When Haslet-Davis performed a rhumba, the artificial foot responded in much the same way a natural foot and ankle would move during the dance. Those dance moves were the result of about 200 days of intense work inside Herr’s MIT lab.

The current BiOM ankles aren’t designed for dancing — or other strenuous activities beyond walking. But Herr envisions a future in which bionic technology can undo all physical disabilities.

Michael B Farrell can be reached at
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