Walk This Way: Paths to Lower-Limb Recovery for Stroke Patients
September 2009 Issue
"Gait training [for post-stroke recovery] usually requires at least one physical therapist, if not two, to help a patient move his or her leg in the proper manner while on a treadmill. Gait centers tell us that they are unable to bill enough to make such a service cost-effective. If the center is able to leave patients a device that gives them the proper therapy, it will decrease their tine at the center, while providing the needed and appropriate gait training."
|Photograph courtesy of Scheck & Siress.|
Each year, two thirds of the more than 700,000 people who suffer a stroke survive the attack and require rehabilitation for what is often a serious, long-term disability. One of the most common disabilities resulting from stroke is paralysis, which can affect the face, arm, or leg on one side of the body-or one entire side of the body. Problems with body posture, walking, and balance can be significant.
Orthotic systems for lower limbs would seem to be one logical solution to restore mobility for such patients-but questions abound: Is there an optimum treatment protocol? What systems work best? Are they curative, assistive, or both? Is there evidence-based knowledge or merely popular consensus regarding orthotic approaches to therapy for post-stroke patients with lower-limb functional losses?
We sought answers to these questions from leading experts in this specialized area of orthotic care.
How Soon to Fit?
According to the National Institute of Neurological Disorders and Stroke (NINDS), "rehabilitation should begin as soon as a stroke patient is stable, often within 24 to 48 hours after a stroke. This first stage of rehabilitation usually occurs within an acute-care hospital."
"Usually it is about six weeks post-stroke when the orthotist is called in to evaluate the patient," says Curt Kowalczyk, CO, clinical specialist-orthotics for Otto Bock HealthCare, Minneapolis, Minnesota. "It would be nice if it were sooner. Off-the-shelf orthotic management of contractures needs to begin while the patient is still in bed and trying to get over the brain injury."
Kowalczyk describes the process by which the stroke patient should be treated, beginning with contracture management during the sub-acute stage.
"You want to position the limb so that when they are ready to get up, there are no contractures to deal with. Even if the patient gets therapy to stretch their heel cord, you've just wasted two hours of physical therapy if they're not wearing some kind of brace to keep their foot properly positioned. If their foot hangs down for 22 hours, two hours of PT isn't going to take care of it."
Once contracture-prevention efforts have begun, the objective is to try to re-engage the person in movement skills, attempting to recover what they have lost, says Stefania Fatone, PhD, BPO (Hons). "The biggest problem with stroke is that patients lose the ability to selectively control individual muscles. The objective of therapy in the early phases is to basically teach someone to move properly again and to voluntarily move their muscles."
The orthotist should be prepared for return of muscle function in no particular order, Kowalczyk warns. If the muscle that turns the foot in begins to work before the muscle that turns the foot out, the orthosis must be built to block that erroneous movement.
"After-fitting service and adjustment is more important in the stroke population than probably any other population," he notes. "You don't know what's going to happen. You have to build for all contingencies throughout the continuum of rehabilitation so that the orthosis can be modified, because even though there is a change in the patient's medical condition, you're going to be hard pressed to get a third-party payer to buy a whole new brace every time a muscle returns."
What System Works Best?
The newest outcome studies seem to support the theory that if the post-stroke subject moves the afflicted limb through a repetitive range of motion, new neural pathways will be mapped out in the brain to avoid the damaged area. This neural "plasticity" allows different parts of the brain to thus take over new responsibilities, and the patient can achieve return of function, Kowalczyk explains.
The stance-control orthosis allows the knee joint to move through its range of motion, which encourages small movements of "trace muscles" and creates new neural pathways.
Systems that lock the knee don't offer this benefit. Kowalczyk cites a study by Assistive Technologies that identifies the negative effects of locking the knee joint(s). "The gait deviations cause increased cardiac and pulmonary stress. Ambulating with locked knees or mobility inhibited by the orthosis causes three out of four patients to abandon their locked KAFOs."
On the other hand, Andrea Pavlik, CO, of Wisconsin Orthotics & Prosthetics, Sheboygan, endorses the use of lightweight braces, such as the new carbon-fiber designs, and avoids using KAFOs on post-stroke patients. "They are way too heavy and bulky. Following the stroke, they've lost a lot of that nerve input that gives them their muscle strength; if we use something too heavy on them, they're not going to be able to advance that leg."
|Photograph of the L300 courtesy of Bioness.|
Functional electrical stimulation (FES) devices like the WalkAide and Bioness L300 work very well for stroke victims, Kowalczyk says, by stimulating the muscle and causing growth, but they do not rely on voluntary contractions by the patient.
"FES is only going to give us contractions of gross muscles," Kowalczyk says. "You're not going to get that fine contraction to control rotation and alignment of the limb. So a brace is still necessary to maintain alignment, and FES will then allow you to have range of motion occurring through that joint and gross muscle firing."
"The FES also promotes neural plasticity...," Pavlik says. "There is evidence that patients can actually regain that function and maintain that function when they're not wearing the device-albeit for a short period of time, but it can happen.
"That's the thing with stroke victims," Pavlik continues. "As we are putting the [FES] devices on more and more post-stroke victims, we are seeing the same neural plasticity happen. Not so much with a traditional AFO because it's working outside the body and replacing the muscle motion."
How long the carryover effect from FES would last is the big question, Fatone says. "There's been some work out of Europe, where they've done a little bit more with FES than here in the States. As far as I know, the results aren't conclusive one way or the other as far as long-term carry-over is concerned.
The Age of the Robot
Robotic technology is offering some exciting new possibilities in lower-limb post-stroke therapy and orthotic management. In addition to the LOPES (LOwer-extremity Powered ExoSkeleton), designed in the Netherlands to help stroke survivors regain walking ability, the Lokomat®-a robot-assisted walking-therapy system-is being studied at the Rehabilitation Institute of Chicago (RIC), the only federally funded stroke-rehab research and training center in the country. (Editor's note: See the March 2009 issue of The O&P EDGE for a detailed discussion about these and other robotic options.)
Newcomers include the PK100-Tibion's bionic leg orthosis-and Berkeley Bionics' Human Universal Load Carrier (HULC).
Kern Bhugra, founder and CEO of Tibion Bionic Technologies, Moffet Field, California, notes that the Tibion PK100 provides powered assist for both rehabilitative therapy and enhanced mobility, depending on the individual patient's need.
A microprocessor-controlled non-invasive device, the PK100 uses its sensors to detect and analyze the biomechanics of the user; as the patient makes an intention of movement, the sensors identify and augment that function.
"As a seated patient starts to stand, the device recognizes the intended action, and within a fraction of a second, responds by providing propulsion to help the patient achieve a full standing position," Bhugra explains. "In reverse, it provides resistance so the patient doesn't fall into the chair as they attempt to sit down. The powered assistance is also beneficial during gait and ascending/descending stairs.
"The user is in control at all times, and the device responds in real time as the actions of the user change."
As the patient provides more power, the device provides less, automatically "dialing back" to compensate as the user's own strength and control increase during rehabilitation.
|Photograph of the Tibion PK100 courtesy of Tibion Bionic Technologies.|
The device is used by inpatient and outpatient clinics as a rehabilitative tool during physical therapy to enhance motor control and recovery. Clinical studies in progress at two San Francisco Bay Area hospitals reveal positive results, Bhugra notes. "Findings with post-stroke patients have demonstrated significant improvements in gait speed, stride length, and endurance. These improvements have been seen not only with patients recently recovering from a stroke but also for those who may be several years since the stroke occurrence."
After six years in development, the PK100 is now entering the market, with an introductory program planned to launch at the University of California, San Francisco, as this issue of The O&P EDGE goes to press.
"Our goal is to establish the Tibion PK100 as the premier stroke-rehabilitation device," Bhugra says. "We believe that tools like the Tibion PK100 are absolutely necessary in solving a huge unmet need in the stroke-recovery process."
Berkeley Bionics HULC
Although initial applications for the HULC were primarily of a military nature-the system's predecessors come from a U.S. Defense Advanced Research Projects Agency (DARPA) program-Nathan Harding, chief operating officer, Berkeley Bionics, California, believes that the medical market for his exoskeleton for human performance augmentation (EHPA) is larger than the military market.
"Part of that is because stroke victims are such a huge market-and it's a place where we can really do a lot of good."
Harding's current HULC-in-progress is "essentially an in-home post-stroke gait trainer-something that can be worn as patients walk around their neighborhoods, getting gait training as they go about their daily lives."
Although the device is pre-programmed so that it can be worn without supervision, the exoskeleton will be prepared for the patient by a physical therapist and leased to the patient by the rehabilitation facility. Adjustments to the programming would be made by the physical therapist as needed.
"Gait training usually requires at least one physical therapist, if not two, to help a patient move his or her leg in the proper manner while on a treadmill," Harding explains. "Gait centers tell us that they are unable to bill enough to make such service cost-effective. If the center is able to leave patients a device that gives them the proper therapy, it will decrease their time at the center while providing the needed and appropriate gait training."
The device uses its sensory input to determine what the unaffected side of the wearer's body is doing and uses that information to provide balanced support and mobility to the affected side of his or her body, Harding says.
Although it is expected to weigh about 25 pounds, the device entirely supports its own weight. A control mechanism will allow the physical therapist to select how much assistance and/or resistance should be applied by "dialing in" the amount of resistance. "At one extreme, the device might do basically all the work for the patient; at the other end of the spectrum, more resistance could be prescribed in order to try to build a certain muscle."
Clinical evaluation on the device should be completed in early 2010; it could be available as a product shortly after that, but it may take another four to five years before it is reimbursable by a patient's insurance.
"It amazes me," Harding says, "that although our current prototype is definitely not pretty-and definitely not a medical exoskeleton by any means-still the patients have been incredibly excited about using it and about the prospect of having something that's training them while they're going about their daily lives."
Fatone is cautiously optimistic about the robotic devices. "From the realm of augmenting human potential to the realm of rehab device, we don't really know yet what we're going to be able to do clinically with these devices," she says.
Pavlik, however, points out that whether the orthotic solutions are robotic or otherwise, there's one rule of thumb: "Any time we can get the body to perform the function that it's supposed to do, that is our best bet and our best treatment plan."
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.