Novel fall-prevention training for war-wounded amputees

Falls are a well-recognized hazard for the elderly. But it is less well known that people who have undergone a limb amputation, particularly above-knee amputations, face an even greater challenge maintaining their balance.

Data show that during a 12-month period, about 30 percent of the members in an elderly population fall. This compares with an annual fall rate of 50 to 60 percent for amputees.

Mayo Clinic orthopedic researchers are striving to improve ambulation by reducing the fall hazard facing U.S. military service members who have undergone unilateral limb amputation. To do this, they are collaborating with a consortium of researchers in a new $2.4 million Applied Research and Advanced Technology Development Award from the Defense Department.

The grant is intended to improve training methods for rehabilitating this group of wounded warriors using advanced technology and novel techniques.

Power and passion for the cause

The program harnesses two key Mayo orthopedic resources. One is its research prowess in biomechanics, gait analysis and prosthesis development. The other is its specialists' passion for serving wounded warriors.

Kenton R. Kaufman, Ph.D., is head of Mayo's Motion Analysis Laboratory and the Mayo specialist on the grant team. Because his previous work developing a microprocessor-controlled knee orthosis had wide application among wounded warriors, Dr. Kaufman developed a deep commitment to improving their rehabilitation.

"I'm very passionate about working with wounded warriors, so this opportunity to participate in this research program is really gratifying," he says.

Creative collaboration

In addition to Dr. Kaufman's command of gait analysis and prosthesis development, Mark D. Grabiner, Ph.D., from the University of Illinois at Chicago, brings expertise from his specialized training method working with the elderly to prevent falling.

Marilynn Wyatt, M.A., P.T., director of the Biomechanics Laboratory at the Naval Medical Center San Diego, adds her expertise in rehabilitation training and conducting studies performed in the state-of-the-art Naval Medical Center's C5 facility (Center for Comprehensive and Complex Casualty Care).

The fall-prevention training is performed in the C5 motion analysis laboratory using a computerized system that allows the researchers to create controlled falls while the amputee walks on a customized treadmill at various paces wearing a safety harness.

The functional evaluations are being performed by Pinata Sessoms, Ph.D., in a state-of-the-art performance analysis system called the Computer Assisted Rehabilitation Environment (CAREN) at the Naval Health Research Center in San Diego. The CAREN system is a fully immersive virtual reality environment for research subjects, including visual, auditory, vestibular and tactile sensory inputs.

Analyzing balance of war-wounded amputees in a new Mayo Clinic collaborative study to prevent falls

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Studying loss of balance in amputees in a fully immersive virtual reality research environment

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Each research subject's body is tagged with 34 retroreflective markers that 12 infrared cameras detect and read. As the research subject walks, researchers introduce "postural disturbances," which create a situation where the amputee might fall into a protective harness, in order to quantify the amputee's response.

All movement data are captured and transmitted to a computer for visualization and analysis so researchers can study the research subject's response to the postural perturbations. From this information, researchers can determine a training program's effectiveness.

First phase under way

The grant is in its first phase, and researchers will begin collecting data later this year from 30 unilateral amputees.

Since the grant was written, the amputee population is changing. The number of bilateral amputees has risen due to casualties in Afghanistan. Compared with Iraq battle conditions, soldiers in Afghanistan are less protected, and therefore more vulnerable to war injuries.

Explains Dr. Kaufman: "In Iraq, soldiers were in armored vehicles, so when an IED exploded, they were protected. Now in Afghanistan they are on foot patrol due to rugged environments. From 2009 to 2010 the number of amputees has almost doubled, but the number of individuals with multiple limb amputations has tripled. Those are very sad facts, and that's why we are committed to trying to improve the lives of these wounded warriors."

The views expressed in this article are those of the authors and do not necessarily reflect the official policy or position of the Department of the Navy, Department of Defense or U.S. government.