Ossur: Design That Walks the Line

To offer a prosthetic foot with greater stability, Hilmar Janusson and his colleagues used innovative software and artificial intelligence

by Reena Jana

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Several years ago, Hilmar Janusson and his colleagues at Reykjavik (Iceland) prosthesis maker Ossur discovered what he calls "a well-kept secret" among below-the-knee amputees.

Applying a user-centered design approach, the research-and-development team at Ossur—supplier for South African runner Oscar Pistorius, the controversial, first-ever amputee Olympic Games hopeful—regularly collects patient anecdotes relayed by clinicians in various nations, including Germany, Belgium, and the U.S. And Janusson, Ossur's vice-president of R&D, spotted patterns in the feedback. Many amputees, Janusson and his team noticed, reported falling when wearing the very prosthetic feet that are meant to help them walk and move about.

But while other medical-device designers may have known about this problem, none came up with Ossur's sophisticated solution: to create a truly lifelike foot that can react in real time to an amputee's motion, similar to a biological appendage. And Janusson's solution was to involve a technology never before used in the field of consumer prosthetics: artificial intelligence.

"If you've ever walked around wearing ski boots, you'll get a sense of what it is like wearing a typical prosthetic foot every day," Janusson says, referring to the inflexible and uncomfortable footwear that alpine skiers wear to keep their ankles stable on the slopes, but which are notoriously difficult to walk in.

A Foot with a Brain

In the clinical reports that Ossur reviewed, many of the amputees wearing stiff traditional prosthetic feet admitted being frustrated. They reported being afraid to take a simple stroll or exercise, but continued immobility for fear of falling could potentially jeopardize their cardiovascular and muscular health, possibly leading to further medical issues such as heart disease.

Learning about this unfortunate secret helped Janusson and his engineering and design colleagues address the user need for a more comfortable, stable, and natural prosthetic foot—one that moved more like a human foot than a cumbersome peg leg. So Janusson, an Iceland native who holds a PhD in chemical science and engineering from Britain's Leeds University, led a team to design a foot that uses motion sensors and advanced software to provide fluid, natural movement. Made of aluminum, the Proprio features hardware that senses and measures ankle and leg motion more than 1,000 times per second, to gauge how fast and in what direction the user is walking.

Proprietary software analyzes the data and then instructs the foot to adjust to the user's movement, so the amputee can walk with ease. The foot also points downward when an amputee is sitting, a more natural, lifelike position not previously achievable in foot prosthetics.

Filling a Need

The advanced bionic foot was released in the fall of 2006, and this June it won a Medical Design Excellence Award, a top industry honor given by the publisher of trade publication Medical Device & Diagnostic Industry. The U.S. Defense Dept. and the Veteran's Administration are currently using the Proprio foot for wounded soldiers returning from Iraq and Afghanistan, as well as for other veterans with amputated feet.

Janusson sees diabetics as another market. Statistics from the Centers for Disease Control published on the American Diabetes Assn.'s Web site state that more than 60% of nontraumatic lower-limb amputations occur in people with the disease. Together, these markets and the introduction of its state-of-the-art, potentially revolutionary device, helped Ossur's worldwide sales in 2006 grow 57%, to $252 million, the highest growth rate in the company's 36-year history.

Integrating Biology and Mechanics

"What really differentiates Ossur from its other market participants is its innovative bionic product platform," writes Archana Swathy, a medical device research associate at Frost & Sullivan, a consultancy headquartered in San Jose, Calif., via e-mail.