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Army Staff Sgt, Felix Chavez navigates the gait lab at the Center for the Intrepid.

Army Staff Sgt, Felix Chavez navigates the gait lab at the Center for the Intrepid. (Leo Shane III / S&S)

EDITOR'S NOTE: This is Day Two of a two-day series about the Center for the Intrepid at Fort Sam Houston, Texas. See the first day's stories here.

Researchers and trainers at the Center for the Intrepid repeat the mantra that everything they do is designed to help amputees reach their full potential.

Now, they have to figure out what that means.

The center’s first-floor research labs, in full operation for just the last few months, are perhaps the most important features in the long-term treatment of amputees and limb-salvage patients.

They include a cavernous gait lab — a high-tech obstacle course to record subjects’ every step — and a 21-foot virtual reality dome. Both are unique diagnostic tools, designed to give prosthetics experts and trainers new ways to evaluate and improve patients’ movements.

“It’s a whole new way to see differences between how amputees walk,” Lt. Col. Rachel Evans, research director for the center on Fort Sam Houston near San Antonio.

The gait lab

The gait lab uses marble-sized sensors taped to patients’ joints with motion-capture cameras to create a digital video of their pace, balance, twists and stumbles — the same technology used in many current sports video games, to capture athletes authentic movements.

Pressure-sensitive pads record how much force their steps push back into their bodies and how much torque the replacement limbs can handle. Different terrains and inclines test the same issues from new angles.

Evans said researchers can use those results to show patients how to avoid back pain and balance problems, and even teach them to run faster. The results will help therapists see likely mistakes for future patients, allowing them to correct those issues earlier in the recovery process.

Environment simulator

The $1.5 million virtual reality dome incorporates some of the same technology but keeps patients on a single treadmill to record their moves.

As images of city streets or a park scene are projected on the 360-degree screens surrounding the patient, computers monitor the walker’s reactions to gentle slopes, sudden noises and even surprise images coming across their path.

“It’s a way to view them in a realistic environment but also let them feel safe,” said Benjamin Darter, research therapist for the center. “It also allows us to integrate the research side with the clinical, seeing how they react and having rehabilitation intervention right away if needed.”

For some patients, that could mean learning how to take longer strides or how to lift their mechanical legs higher off the ground, he said. For others, it could mean learning how to walk through a crowded city street without bumping into others or getting claustrophobic.

Next steps

But before the labs can be put to full use, researchers have to figure out how to walk.

“We still really don’t know what ‘normal’ is, or what it should be for different sizes and shapes,” Evans said.

Staff in the labs have spent the last 10 months compiling complex information on how everyday people step and lean, slowly establishing a baseline off which to judge the movements of patients with prosthetics. Shorter patients might get more efficiency with certain hip moves. Heavier ones might need slower steps. The results are sent upstairs to the prosthetics labs, where the information is used in the latest designs.

That work is nearing completion, officials said, and the next step will be bringing wounded troops into the labs.

Some of the initial work will be to diagnose patients’ progress, but researchers also will see how they react to the feedback, testing assumptions about limb comfort and efficiency.

“These are young men and women in top physical condition,” Evans said. “This population is going to do more than get up and walk to the TV to change the channel. They’re going to try to win gold medals.

“So we need to learn how to help them do that.”

See the Day 1 stories here.

See a photo gallery here.

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