Preventing falls in wounded warriors
A Mayo Clinic expert in the biomechanics of human movement initiated a multicenter team to develop a novel rehabilitation method that helps prevent falls in servicemen and women with leg amputations and is transferable to the civilian population. The U.S. Department of Defense has granted $2.4 million for the collaborative study.
Nearly 170,000 people in the United States have lost a leg because of a disease or accident, or in the case of men and women who have served in the Armed Forces, to battle-related trauma. Advances in prosthetic leg technology have produced bionic legs that encourage a more symmetrical gait and improved balance and require less energy for walking.
However, people still stumble or trip. In fact, people with a prosthetic limb fall at almost twice the rate of older adults, often resulting in complicated injuries and lifestyle limitations. Studies have shown that during a twelve-month period more than 60 percent of above-knee amputees fall — a statistic that Mayo Clinic biomechanical engineer Kenton R. Kaufman, Ph.D., P.E., is working to change.
"They have great motor control, but they are not confident that the prosthesis will be there when they need it," Dr. Kaufman says. "Our goal is to teach them how to use their prosthesis efficiently, increase their confidence and reduce the frequency of their falls."
Dr. Kaufman, who directs the Motion Analysis Laboratory at Mayo Clinic, is passionate about helping wounded veterans and wants to improve their lives and those of all people with lower limb prostheses by focusing on rehabilitative training methods for those who have lost their legs in battle. The technologies and techniques developed for the military can easily be transferred to civilian need as well.
To do this, he launched a collaboration that resulted in a consortium of researchers and a $2.4 million Applied Research and Advanced Technology Development Award from the U.S. Department of Defense Medical Research and Development Program.
An international reputation in the analysis of human movement
Dr. Kaufman has earned an international reputation in the development and application of innovative techniques for dynamic assessment of musculoskeletal function and modeling in humans. Assessing a musculoskeletal problem while a patient moves is much more effective than examining a single, static image. Dr. Kaufman has developed electrical and mechanical systems to improve mobility for all kinds of human motion, such as gait, wheelchair propulsion, use of braces and prostheses, and dynamic balance. His lab at Mayo Clinic is equipped with a variety of surface conditions in which researchers can more accurately assess needs and develop individual treatment plans for patients with a variety of neuromusculoskeletal problems.
Dr. Kaufman is also an expert in orthotics and has a patent for a microprocessor-controlled knee brace that is available commercially. The brace has had wide application among both wounded veterans and nonmilitary patients alike, but it triggered his eagerness to direct many of his research projects toward helping veterans. His research has also helped decrease overuse injuries in military recruits and is responsible for a combat boot worn by U.S. Marine Corps troops.
His current projects include a study to try to understand why people get shoulder pain, with particular focus on the loads wheelchair users put on their shoulders. Another project involves tele-rehabilitation — an innovative use of modern technology that has physical therapists using Skype to watch patients perform recommended exercises in their home to ensure that they are doing them correctly.
Developing a protocol with the U.S. Navy
The fall prevention study would not be possible without the expertise and technology provided by the U.S. Navy. The clinical investigation is being carried out at the Naval Medical Center San Diego and the Naval Health Research Center in San Diego. Marilynn Wyatt, P.T., M.A., director of the Gait Analysis Laboratory at the Naval Medical Center and a former colleague of Dr. Kaufman's, is leading the clinical team performing the evaluation and training trials. Pinata Sessoms, Ph.D., is a biomedical engineer who analyzes the performance of study volunteers by operating the Navy's highly sophisticated Computer Assisted Rehabilitation Environment at Naval Health Research Center.
As the team began developing the protocol for the study, researchers were excited to learn about a successful technique for fall prevention in older adults at the University of Illinois at Chicago. Mark Grabiner, Ph.D., directs the Clinical Biomechanics and Rehabilitation Laboratory there.
"The library of human motion is highly complex because it involves the coordination of multiple joints that are operated by many muscles," Dr. Grabiner explains. "However, the brain has an amazing ability to figure out the ideal way to respond to whatever motion is required. If a previously learned action, like riding a bike, is required after a long period of neglect, the brain does not take long to reproduce it."
The traditional approach to improving motor skills is to deconstruct motor patterns into their separate components and practice changes in sequence. Dr. Grabiner's hypothesis for improving falls in older adults is to train the task as a whole.
"The approach is elegant in its simplicity," Dr. Grabiner says. "We supply a safe place where they are not afraid to fall, then trip them and let the brain figure it out."
Dr. Grabiner is conducting a prospective, randomized trial in which he has been able to cut the fall rate of older adults in half with just four one-hour visits over a two-week period — results that made the team eager to collaborate with him. Nevertheless, gait problems differ significantly between older adults and younger, stronger and more active people who have undergone leg amputations. Having to control a prosthetic leg makes motion much more complicated.
"Dr. Grabiner's premise is that the elderly have simply forgotten how to take evasive maneuvers to prevent a fall," Dr. Kaufman says. "Wounded warriors tend to rely on their sound limb, so our work has been to modify his technique in order to develop a prosthetic rehabilitation algorithm."
Taking advantage of the Navy's cutting-edge facilities
Patients are tested before and after the rehabilitation program in the Navy's Computer Assisted Rehabilitation Environment system. It consists of a platform containing a 6-foot long, split-belt treadmill that has an independent integrated force plate under each belt. Dr. Sessoms can program it to pitch or roll in any direction, independently or simultaneously.
Patients are surrounded by an 8-foot tall, 180-degree screen displaying images synchronized with the movement of both the platform and the patient. Twelve motion-capture cameras pick up every movement. The patient is fully immersed in a virtual reality environment, with visual, auditory, vestibular and tactile sensory inputs.
To evaluate the functional characteristics of each patient's gait and balance, 34 reflective markers are placed in strategic positions on the patient's skin. Tests include walking and tripping attempts with a protective harness. The data is transmitted to a computer and analyzed to determine the effectiveness of the training program.
The rehabilitation itself takes place in the gait lab at the Naval Medical Center San Diego's Comprehensive Combat and Complex Casualty Care (C5) facility. The facility manages the care of severely wounded veterans from medical evacuation through inpatient care to outpatient rehabilitation. The gait lab also performs computerized motion analyses with reflective markers attached to anatomical landmarks on the patient's body.
"Often, the patients do not depend fully on their prosthetic leg during the first training session and depend on the harness for support," Dr. Kaufman notes. "After six sessions, when they have re-educated their motor control system to respond properly, most are able to withstand the postural disturbances and don't fall or require support, even at twice the speed."
Study volunteers attend six training sessions over a two-week period. They are followed with re-evaluations at three and six months after training. During the six-month period, they also document any stumbles and falls.
Justifying a prosthetics advance
In 1999, Ottobock Healthcare released its prosthetic C-leg. Until then, the standard prosthesis for active people with amputations above the knee was a mechanical knee developed in 1958. The C-leg has a microprocessor on board that makes hydraulic adjustments in response to the patient's movements. However, it was much more expensive that the existing mechanical leg and insurance companies typically needed justification of its worth before they would agree to cover it. It was Dr. Kaufman's expertise that Ottobock sought in 2000 to investigate whether or not its new prosthesis was more effective than the existing mechanical leg.
"We conducted a series of studies and showed that people who changed from the mechanical to the microprocessor technology had better gait, balance and gait symmetry," Dr. Kaufman says. Those findings were later published in the journals Gait & Posture and Clinical Biomechanics.
"People with lower extremity amputations curtail their activity because walking with the mechanical knee is exhausting, and they're also afraid of falling," Dr. Kaufman says. "In our study, they voluntarily increased their daily energy expenditure by about 8 percent when switching to the microprocessor-controlled knee." The findings were published in the Archives of Physical Medicine and Rehabilitation in July 2008.
As a consequence of his research, Blue Cross Blue Shield organizations across the country, which had considered the C-leg an experimental device until then, changed their policies and agreed to cover it. Dr. Kaufman modestly credits personal testimonials of amputees as having a greater effect on insurance coverage than his research report did.
"There was a Vietnam vet with the impressive story of having fallen 500 times in 30 years with the mechanical leg," Dr. Kaufman recounts. "His falls had caused injuries that required expensive surgeries. He became much more active with the C-leg, recalls only falling twice in three years and lost 40 pounds. That brought his high cholesterol and blood pressure under control, and they no longer had to pay for medications to control them. It was a good feeling to know that the science supported his testimony."
Additional Mayo Clinic efforts help wounded veterans
Under the umbrella of another consortium funded by the Department of Defense (DOD), Mayo Clinic orthopedic surgeon Michael J. Yaszemski, M.D., Ph.D., is using regenerative medicine to develop new products and therapies for the Armed Forces Institute of Regenerative Medicine. Dr. Yaszemski, who also serves as a brigadier general in the U.S. Air Force Reserve, has deployed to Iraq as deputy commander of the Air Force Theater Hospital in Balad. Other Mayo Clinic investigators involved in the consortium are orthopedic surgeons Allen T. Bishop, M.D., and Alexander Y. Shin, M.D., neurologic surgeon Robert J. Spinner, M.D., and neurologist Anthony J. Windebank, M.D.
Dr. Kaufman is also director of scientific cores for a DOD-funded consortium called Bridging Advanced Developments for Exceptional Rehabilitation. This consortium seeks to have wounded veterans reach their optimal level of function with evidence-based orthopedic rehabilitation developed by collaboration between military and civilian treatment facilities, the Veterans Affairs, and the scientific community.
If the training protocol produces the enhanced functional capability or accelerated rehabilitation that the consortium desires, they will deploy the clinical consortium systemwide throughout the military and Veterans Affairs. In addition, all of the teaching and rehabilitation techniques are transferable to the civilian population.
"So far all participants have uniformly hated the training — it's tough," Dr. Kaufman concedes. "But they are quick to add that it has helped them because rather than being taught how to fall, our training teaches them how not to fall."
— Volume 8, Issue 2