FDA mulls ‘Avatar’ tech for evaluating prosthetics

A computer reads reflective markers (shown here) attached to a test subject as she undergoes a dexterity test. (Courtesy of the FDA)

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Could the technology used to help actors portray monsters in films like “Avatar” and “The Hobbit” help the Food and Drug Administration, and manufacturers, better evaluate artificial limbs?

A group of FDA researchers say they’re working to find the answer. They’re integrating 3-D motion capture technology into a classic test that gages dexterity in the hopes they can measure what extra body movements prosthetics users must make to compensate for the limitations of their devices.

Eugene Civillico, a neuroscientist in FDA’s Functional Performance and Device Lab, said the research could eventually help manufacturers find ways to make better prosthetics — critical work as more troops return from conflicts abroad with missing limbs. According to a report from the Congressional Research Service this summer, there have been more than 1,600 major amputations (referring to the loss of a limb or a similar trauma) in the War on Terror since 9/11.

“It’s very, very important to be able to help these patient populations,” Civillico told FedScoop.

Clinicians have typically used the “box and blocks” test, which measures how quickly a test subject can move blocks from one bin to another, to help judge dexterity. But those results don’t always tell the whole story, said FDA research fellow Kimberly Kontson.

“There are some prosthetic users that have become quite proficient in using some of these simpler prosthetic devices, such as body-powered hooks,” Konston said. “They can actually perform this task just as well as somebody without a disability. But if you watch them do it, they’re going to be shrugging their shoulders and twisting their torsos and shifting their head to achieve this task.”

To take that into account, researchers are fitting test subjects with small reflective markers that allow a computer to track the subjects’ upper body movements in real time. To simulate restricted movement — like what a patient might experience while using a prosthetic — the team is binding the fingers or bracing the wrists of able-bodied test subjects.

“What our lab is trying to do is develop a framework to incorporate this movement quality” into the evaluation of the performance of prosthetics with amputees, Konston said. She added that in addition to the 3-D tech, the team is also evaluating the prospects of measuring subjects’ brain waves to record what kind of mental workload it takes to complete the task, and they’re using a special platform to judge changes in weight distribution.

The 3-D technology itself is nothing new, Civillico said: Motion capture has been around since the 1980s, but once movie studios started using it in films like “Avatar,” the technology rapidly advanced. He said other labs are also researching the use of this technology in prosthetics.

In the months ahead, the FDA lab wants to start conducting similar tests on patients who use prosthetics. Ideally, Civillico said, his lab’s research would help industry conduct better tests of their own and help FDA examiners better evaluate applications.

“What we really hope is that the ideas we come up with here have an impact on sponsors who create medical products submissions and they’ll use the ideas we put out into the world to make their products better — and that our colleagues in premarket review offices will use our ideas to ask the right questions,” he said.

A manufacturer can submit any data to FDA that it believes supports its claims during a review. Some artificial limits that use “novel technology” may require a premarket review, but most don’t. They are, however, subject to general controls for low-risk devices.

The FDA lab’s 3-D motion capture research “sounds very much consistent with what might be done by an academic researcher or a clinical researchers out there in the field,” said Jason Highsmith — the president of the American Academy of Orthotists and Prosthetists, deputy chief of research and surveillance for the Extremity Trauma and Amputation Center of Excellence (EACE) under the departments of Defense and Veterans Affairs, and a researcher the University of South Florida. He’s also heard of manufacturers using similar technologies.

At the EACE, Highsmith oversees research that evaluates how well prosthetic devices are working for vets and warfighters. Patients often select the prosthetic that works best for them, he said. But 3-D motion capture can illuminate why a patient likes or doesn’t like a given device.

“It’s complicated, time consuming, and it’s usually an expensive endeavor,” he said of motion capture. “But it certainly, for us, has helped with sort of the mechanistic understanding for why patients prefer a certain device over another.”

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Department of Health and Human Services (HHS), Departments, Food and Drug Administration, veterans
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