Powered AFOs: New Roles for Evolving Technology

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Portable Power-Assist AFO. Photograph courtesy of the Georgia Institute of Technology.

Considering new roles for technology that isn't ready for prime time in its original form may seem inappropriate. However, for nearly 20 years, researchers worldwide have been striving to develop robotic or powered orthoses for definitive use, and while such devices may not be ready for everyday use, they may be much closer to readiness for practical use and service as diagnostic and rehabilitative tools, suggests Géza F. Kogler, PhD, CO, coordinator of research and instructor of orthotics for the master of science in prosthetics and orthotics (MSPO) program at the Georgia Institute of Technology (Georgia Tech), Atlanta. As such, Kogler says, these tools offer the potential to dramatically expand the clinical orthotist's scope of practice.

Kogler, who is also the director of Georgia Tech's clinical biomechanics laboratory, became involved in a powered AFO research project six or seven years ago. Driven by the Center for Compact and Efficient Fluid Power (CCEFP), a National Science Foundation (NSF) Engineering Research Center, and funded by an NSF grant, the power-assist AFO project is a collaboration between the University of Illinois at Urbana-Champaign, Georgia Tech, and the University of Minnesota, Minneapolis. The goal of the project was to create a device for everyday use. Such a device would enhance or replace the function of the calf muscle, providing push-off during ambulation. Unfortunately, attempts to achieve this goal have had limited success, says Kogler, who is the lead researcher on the development of the Portable Power-Assist AFO, currently in prototype form. (Editor's note: For more information, read "Beyond Control: The First Untethered Power-Assist AFO," The O&P EDGE, October 2011.)

"It takes quite a high-powered output to be able to duplicate that force, so we developed an AFO that provides assistive power," he says. "We were successful at getting this device to provide some powered assistance that emulates the normal timing events of the walking cycle. The AFO has several sensors that determine when the actuator must provide the power assistance during walking and/or ascending or descending stairs.

"At the moment, the dimensions and weight of the AFO still need to be scaled down, but I'm not sure the AFO will ever be able to compete with the much lighter-weight passive devices that are currently the standard of care."

It was in the process of creating this untethered, power-assist AFO, however, that Kogler and his team realized the rehabilitative potential of the device, which could be much closer to actualization than the end-user function the researchers had originally envisioned.

"The normal restorative care for patients with a pathological inability to move their ankle and foot would be a passive device—an AFO," he explains. "An active device offers power during gait, and from a rehabilitation standpoint, that is where the advantage is."

The rehabilitative process normally includes a physical therapy protocol involving stretching and strengthening exercises designed to restore patients to a comfortable level of mobility in society. That type of therapy typically requires contact time—when therapists work with the patient from three to five days a week in a care center or outpatient setting while the patient receives strengthening and gait training on a treadmill. During this period, one or two therapists provide guided assistance to make sure the patient is able to safely perform those activities. Alternatively, Kogler's untethered, power-assist AFO device can be programmed by a researcher to create, for example, a treadmill-like walking routine for the patient to perform safely in his or her own home environment—without a treadmill, and without a therapist's assistance, Kogler explains. Specific repeatable settings would allow the patient to don the AFO at home, hit a button for his or her programmed walking routine, and begin therapy.

The device offers additional therapeutic possibilities as well. "The patient could lie down in bed, don the AFO, and it can provide a resistive exercise, applying controlled resistance as a strengthening routine," Kogler says. "Or it could provide passive range of movement since the power drive can take the ankle through its full range of motion and hold it for a period of time to stretch the ankle out. It wouldn't be necessary to make a trip to have the therapist do that by hand."

"The cost savings would be tremendous," he continues. "These various rehabilitation routines could actually be programmed remotely and sent to the device user via computer link or by cell phone. The device could record how successful the user is at completing those tasks and maintain a record."

As an AFO with added features and capabilities, the device offers orthotists an opportunity to extend their current scope of practice. As rehabilitative devices, the powered AFOs must be fitted, programmed, and monitored, Kogler points out. "There is a market, I think, for that care."

Contemporary master's degree programs in orthotics and prosthetics expose students to these rehabilitative devices, Kogler adds.

A number of laboratories around the world are also building robotic orthoses, but until now most of the emphasis has been on devices that provide therapy for patients with paraplegia, allowing them to simulate walking in a therapeutic routine under the control of a therapist. The cost of this process is high and serves an extremely limited number of potential users, Kogler says. Comparatively, AFOs are one of the most commonly fit devices orthotists provide, serving a large population of users.

"While the use of robotic devices in rehabilitation is not a new idea, no one has yet targeted the population that would have the greatest need and demand for it. Our current powered AFO system is capable of providing these advantages. For use as a definitive device for everyday wear, the componentry might have to be scaled down, but for rehabilitation purposes, we're actually not that far off. I predict that within five to seven years, this idea will be ubiquitous because of the cost savings."

Steve Fletcher, CPO, LPO, director of clinical resources for the American Board for Certification in Orthotics, Prosthetics & Pedorthics (ABC), agrees that while it might take 15–20 years to incorporate the powered AFO into a definitive orthosis for an end user, a therapeutic or diagnostic version of the device might reasonably be developed and introduced much sooner.

"The orthotist is the key element here because for this type of device to really function appropriately and optimally, it has to be incorporated to a custom-made orthosis. That's the orthotist's role, obviously."

With the advent of new technology and plastics, many of the devices that previously had to be custom made—especially on the orthotists' side of the profession—have transitioned over the last 20–25 years into prefabricated devices, Fletcher notes.

"So I can anticipate that there will be manufacturers that will want to mass produce this type of device—a pre-made, externally powered AFO that you simply adapt to fit the patient while they're in their rehab setting, and use it as a training tool. I think that would be a mistake because the effectiveness of an externally powered orthosis will be dramatically affected if it's…fit as a 'one-size-fits-all' device. The old adage is that if one size fits all, it means that one size fits none."

Fletcher describes the problems inherent in marrying a premade brace to a motor that forces it to move. "Any power that's forced through the motor into the brace will lose efficiency because the device doesn't fit the person intimately enough, so the orthotist would certainly have to be a big part of utilizing this technology. The therapist will also have to play a role. Because the therapist is in charge of that person's rehabilitation, the orthotist and therapist really need to work together."

Kogler envisions patients visiting an orthotist and walking out with a self-contained "suitcase" to take home, where they could safely, conveniently, and inexpensively perform large elements of their own therapy without assistance or supervision, saving travel time and costs to them and those payers responsible for their rehabilitation costs.

"The benefits and savings are enormous—that's why I'm so confident that this will soon be an enthusiastically accepted reality," Kogler says.

While it could be argued that as a therapeutic device, the Portable Power-Assist AFO would be considered a therapist's tool rather than an orthotic device, Kogler points out that therapists are not trained in the skill set that the growing population of master's-level orthotists currently possess.

"We have people entering the field who also have degrees in biomedical engineering and mechanical engineering and electrical engineering," Kogler explains. "These are the people who can design and work with these systems and have the skill set to do it at a much higher level than the traditional therapists. I believe that this is an area where [the orthotist's] scope of practice can be expanded because we have the perfect skill set for it."

Mike Allen, CPO, FAAOP, clinical director of Allen Orthotics & Prosthetics, with locations in Midland and Odessa, Texas, agrees. "In states where licensure exists, the scope of practice of an orthotist is well established. So from a scope standpoint, an orthotist in a state with licensure could certainly provide that level of care. Even with emerging technology, that still falls within the scope of practice of an orthotist, but it's that orthotist's responsibility to be competent with providing that level of care."

From a diagnostic perspective, a powered AFO also has strong appeal, Kogler notes.

"Because this device can be controlled in a very precise way by the clinician, the device could be used as a diagnostic tool to evaluate someone's needs or to determine what the final prescription should be to actually provide a passive device," Kogler says. "Certain control features could be tested with the powered system and then maximized for implementation in a passive device.

"That's why I think that the diversity of these systems can increase their use," he continues. "If it's demonstrated that the ability for that diagnostic test produces more favorable outcomes, it might transition to the point where a diagnostic test using these new types of technology might be used to provide an orthosis."

One of the greatest problems Kogler anticipates with introducing powered-AFO rehabilitative technology to the marketplace lies with reimbursement. He points out that although the stance control orthosis, with its undisputed benefits to wearers, has been around for more than a decade, its prescribed use has been stalled by limited reimbursement. Fletcher notes similar difficulties related to reimbursement for the functional electrical stimulation (FES) devices currently available.

Allen agrees that the utilization of the level of technology Kogler describes also may well be controlled by the payer community. "With emerging technology investigative-type devices used in a diagnostic framework, there may be less likelihood of a payer recognizing it as contemporary practice," he says. "If it's used as an evaluation device, evaluation lends itself to a temporary use and not a permanent use. There may be an opportunity to use it as an evaluation tool to demonstrate favorable outcomes and meeting certain necessary goals, but then something should follow that evaluation, which in my mind would be a definitive orthosis."

The encouraging difference Kogler sees in regard to reimbursement, however, is the cost savings that can be documented through the rehabilitative use of the powered AFO. "As an everyday user device, the medical reimbursement is not going to be there to support it, but the market for its use as a rehab tool is. That's why you're going to see the explosion when it comes to the robotic AFO's acceptance in that role.

"I think the problem is going to be jockeying for position to gain that market share—whether by therapists, orthotists, or even a specialty group of biomedical engineers who conduct the test, provide evidence of its usefulness, and find a way to get reimbursed for it. I'm convinced that the market is going to drive its future role. It's important for orthotists to get on board before someone else does."

Judith Philipps Otto is a freelance writer who has assisted with marketing and public relations for various clients in the O&P profession. She has been a newspaper writer and editor and has won national and international awards as a broadcast writer-producer.

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