By Deborah Conn

The most newsworthy research is not necessarily the most compelling. Glamorous innovations grab headlines, but smaller, more specific projects can have the most impact on a practitioner’s day-to-day clinical work.

As a result, some researchers advocate focusing on “here and now” projects. Steven A. Gard, director of the Northwestern University Prosthetics Research Laboratory and Rehabilitation Engineering Research Program, puts it this way: “What do orthotists and prosthetists want? What do their patients comment on?  Those are the needs we want to address.”

The O&P Almanac asked Gard and other investigators focused on short-term, practical research to describe their work and its possible impact on the daily practice of O&P.

Do prosthetic ankle joints help gait?
Gard recently completed a study funded by the National Institutes of Health that investigated how prosthetic ankle joints affect ambulation in people with bilateral below-knee amputations. “It seems like competition among manufacturers is fierce as they continue to come out with new foot and ankle components,” he says. “We wanted to determine whether [ankle components] do in fact improve gait, and we chose bilateral amputees because they are less able to compensate using the sound leg.”

The study involved objective measurements as well as more subjective questionnaires. Nineteen subjects, all amputees for at least two years, were fitted with the Seattle Lightfoot 2™ as a baseline foot. After two weeks, their gait was tested; then they were fitted with either the Otto Bock Rotator™ or the Endolite Multiflex Ankle Unit™, which they wore for another two weeks.

“We tested them, switched the units, and tested them again in two weeks,” explains Gard. “Then we fit them with both sets of components together, one on each leg, and tested them again after [another] two weeks.”

As is often the case, says Gard, the results were not scientifically profound. “We observed that the ankle units increased ankle motion, as expected, but walking speed, step length, and cadence were not significantly affected in the lab setting.

“Nevertheless, subjects reported that their gait was smoother, it was easier to climb stairs, and turning was easier. At least one subject felt the motion better replicated what he had prior to the amputations.”

Gard concluded that he probably would not recommend ankle units for every patient. “But I think for active individuals, ankle units would be useful,” he says.

Gard also pointed out that the study establishes some important basic information on gait. “Until now, we have had no studies documenting the typical gait of persons with bilateral below-knee amputations,” says Gard. “Now prosthetists can evaluate the gait of patients with bilateral BK amputations and determine whether they are typical or not. It may not affect treatment, but it will help them know what to expect in the rehab situation.” Gard has published two papers so far: one on the typical gait he found, and one comparing the gait of amputees due to trauma vs. amputees due to vascular disease.

Are C-Legs™ good for older patients?
Brian Hafner, Ph.D., is the research director for Prosthetics Research Study (PRS), a Seattle-based nonprofit.
One of its recent projects focused on the use of the microprocessor-controlled Otto Bock C-Leg™ by older, less-active individuals.  

“C-Legs are typically reserved for the most active individuals,” he explains. “We may have overlooked the possibility that older, more unsteady individuals could also benefit from advances in technology.”

According to Hafner, the results of the study indicate that there are indeed benefits for less vigorous, older people. Once users transitioned to the C-Leg, they showed improved satisfaction, suffered fewer tumbles and falls, and were better able to walk down stairs and hills. “The technology doesn’t just improve performance, but can also improve safety,” he says.

Hafner emphasizes that PRS research “measures how things work in the real world, not in the controlled environment of a lab.” To that end, “we used a patient questionnaire and developed some novel outcome tools to assess the C-Leg in real-world situations,” says Hafner.

Working with a team of physical therapists, prosthetists, surgeons and engineers, PRS created the Stair Assessment Index and the Hill Assessment Index, which described each subject’s quality of movement while walking in these situations.

Another innovative part of the study was that subjects were given as long as they needed to fully adjust to the C-Leg. “Usually researchers use a set period of time, from a few minutes to three months or so,” Hafner explains. “In our study, some people accommodated quickly—in a week or two—and others took up to eight or nine months. It’s amazing how often personal accommodation time gets overlooked in research.”

How do you cool a hot socket?
At the Center of Excellence for Limb Loss Prevention and Prosthetic Engineering in Seattle, investigators aim for their projects to have a clinical impact within five years. But that’s not always possible.

“Sometimes we need to fill in some of the unknowns before we have an intervention solution,” explains Principal Investigator Glenn Klute, Ph.D.

For example, he was involved with a project that explored the thermal discomfort of modern socket systems. Researchers found that before they could come up with a solution, they needed to define the problem more precisely.

Klute determined that simply putting on a prosthesis raised skin temperature only a half degree. But walking in it raised the temperature by an uncomfortable two degrees, and when the subject rested, the temperature did not fall. Investigators concluded that a cooling intervention would need to work only when patients were moving.

Another part of the study sought to learn whether the environment would affect socket temperature. After subjects went snowshoeing in the mountains, Klute concluded that the cold weather had no impact on the temperature within the socket.

Finally, Klute looked at the thermal conductivity of liners already on the market. “We looked at 20 or 30 different liners,” he said, “and found that none transferred heat effectively.”

Now that the preliminary research has been completed, Klute says, “We know that we need to put effort into finding other materials.”

What kind of foot do amputees need?
Another project has focused on prosthetic feet. “We wanted to look at how people really use these prostheses,” says Klute. “Do they walk for a long time or for short bouts? We found that most amputees typically walk for one 15-minute duration a week. Otherwise, they’re walking for one or two minutes and doing maneuvering tasks, like turning and twisting.

“These people need a prosthesis that can modulate its stiffness properties, so that it is more rigid for a longer walk and more compliant for short bouts with twists and turns.”

Klute and his team have developed a prototype that uses a motor drive to adjust the stiffness of the foot. The next step is to develop the control. “I would like it to be automatic,” he says, “using either environmental sensors that notice turning and twisting, or a system that relies on electrical impulses from muscle contractions.”

Can children learn with knees that bend?
According to Mark Geil, Ph.D., associate professor and director of the Biomechanics Laboratory at Georgia State University, the conventional wisdom is that articulating prosthetic knees are not appropriate for young children.

Geil challenged that assumption in a recent two-part study. In the first, infants attempted to crawl in a straight line with a locked and then an unlocked knee.

“When the knee is locked, we saw a counter trunk rotation, where the shoulders and hips have to contort themselves more to accommodate the leg that’s hanging out to the side,” says Geil. “We also saw that the other knee had to flex more and lead that side forward to drag the other leg behind. We didn’t see these adaptations when the knee was allowed to bend.”

The second part of the study looked at other functional activities. “We had a padded seat that kids could climb up and sit in, a little table with toys on it, a toddler slide, and padded steps,” he explains. “We were interested in seeing how children would respond to things we don’t test in the gait lab, but that have important implications in their motor development. Children need to explore their environment and play to develop muscles and motor control and proprioception—and to develop their minds.

“We found through observation that the articulating prosthetic knee allowed children to participate more in these activities. Kids with the locked leg would become frustrated.”

Geil plans to extend the study to follow the subjects as they learn to walk. “We’ve seen extraordinary evidence that they do just fine when they are learning to walk with a bending knee,” he says.

Do AFOs affect the knee?
Stefania Fatone, Ph.D., BPO(Hons), is a research assistant professor in the Prosthetics Research Laboratory and Rehabilitation Engineering Research Program at Northwestern University. Her primary area of research concerns ankle-foot orthoses (AFOs) for individuals who have suffered a stroke.

A recent study looked at the ability of orthoses to control knee hyperextension and the turning force acting at the knee.

“We studied 16 people who were two years post-stroke. They came to the motional analysis lab and we measured them walking with AFOs,” says Fatone. “We found that an AFO with a plantarflexion stop can reduce [existing] knee hyperextension [or] delay its onset.”

“Although we felt as clinicians that the AFO was influencing the knee, this had not been well documented in people with stroke,” says Fatone. “We need quantitative information to argue the effectiveness of a device. And we need to prove effectiveness with data to justify reimbursement.”

How can RGOs be used more?
Another area of study for Fatone and graduate student William Brett Johnson is looking at reciprocating gait orthoses (RGOs) for people with spinal cord injury and paralysis. “RGOs are not used for functional walking as much as we would like, because they are too labor-intensive for people with spinal cord injuries,” she explains. “While we have documentation that RGOs are more labor-intensive, there is not much data to indicate what makes them labor-intensive. What aspects of walking with an RGO contribute to increased energy expenditure?”

Fatone’s research revealed that these patients walk with a flexed trunk posture. “This created certain forces at the shoulders and hips that make it harder to progress forward. If we can figure out why they are doing this, and if we improve RGO design or user technique to eliminate it, then walking with these devices might be less laborious.”

“Everyday” research works
Certainly, there is an art to helping damaged bodies regain function, even grace. But the science of how to effect those changes is the foundation of the profession. The gee-whiz science of exciting innovations is an important element, but the studies that address questions that arise day in and day out can make an enormous difference in patients’ lives. And the more hard data that underlie the choices made by practitioners, the devices fashioned by manufacturers and the decisions by third-party payers, the better the field will become.

Deborah Conn is a freelance writer based in Falls Church, Virginia.