The day may soon arrive when corporate and government offices nationwide will be outfitted with a gait analysis system at the front door, this as a means of verifying the identity of everyone who enters the building. For it so happens that step length, step width, walking speed, cycle time, joint rotation and joint angles of the hip, knee and ankle, and several other gait-related parameters can biometrically identify individuals, much like a retina scan or a thumb print matchup.

Should gait analysis ever become widely employed in this manner, it will demonstrate that equipment research and development of recent years has successfully endowed this technology with remarkable capabilities. But even if such a use never catches on, the idea that gait analysis equipment can be good at detecting imposters and security risks leads one to conclude that these systems must be beyond good at their primary intended purpose of detecting ambulation pathologies and fall risks.

Take, for example, the Gait Trainer 2 system from Shirley, NY-based Biodex. It is said to be the only treadmill on the market with an instrumented deck that monitors and records step length, step speed, and right-to-left time distribution. Among its features are a high-resolution color touch screen LCD display and the ability to collect normative data, monitor user heart rate, and store progress records and reports for up to 500 patients. It can be used in harmonious conjunction with Biodex's unweighing systems.

Gait Trainer 2 proves its worth daily in the therapeutic programs overseen by Mitch Carr, MS, Ed, at the Rehabilitation Institute of Chicago, where he serves as director of fitness, sports, and recreation. "We own two of these systems, and we use them extensively in the rehabbing of stroke survivors and Parkinson's patients," he says. "For those patients, we've developed regimens that feature lower-extremity core strengthening, balance programming, and coordination training, all of which are combined with gait training. Especially with some of our newcomers, we're putting individuals on the gait training systems at a minimum of 2 days a week—3 days a week, if possible."

Carr says an advantage of the Gait Trainer 2 is its audio and visual biofeedback functions, which can be therapist—or user—controlled via the touch screen display. Biofeedback, Carr indicates, helps patients develop proper step length, step speed, and step symmetry. "Having an individual look at the video biofeedback screen while walking on the treadmill is a good way to retrain the neuromuscular hard-wiring, if you will," he explains. "Once they've passed that phase, we can continue to use the Gait Trainer 2 to make sure they stay within that proper step pattern, within that proper step length, and are timing their right-versus-left patterns appropriately."

Mitch Carr, MS, Ed, works with a client on proper foot fall, specifically working on improving the client’s heel-strike phase of his step pattern.

PREVENTING FALLS

Gait analysis systems with biofeedback capabilities are playing an increasingly important role in the development and implementation of fall-risk strategies.

Says Carr, "Identifying those at risk—and accurately quantifying the degree of that risk—is essential for rehab programs working with the elderly, stroke survivors, and Parkinson's patients. The aim here is to prevent the breakage of hips and bones, injuries that result in setbacks against whatever rehab goals exist for that particular patient. Over the last few years, we've been utilizing the Gait Trainer 2 as part of our own fall-risk reduction program. We look at challenging the participants, those who have passed more of the basic skills in the early rehab process, by creating for them real-life environments inside a comfortable rehab setting."

He says the Gait Trainer 2 system allows for the simulation of such environments. "What we do is add small obstacles to their gait training regimen," Carr offers. "These obstacles include small pieces of foam that they have to step over as the treadmill is moving. The foam pieces are meant to represent obstacles they'll encounter on the outside, such as curbs, transitional parts of sidewalks, and various uneven surfaces. We keep the patients' gait pace on the treadmill at a slow speed, because our interest is in working with them on visual cues and responses more than anything else at this stage."

Another gait product of note in the fall-risk prevention category is the Balance Quest™ computerized dynamic posturography system from Chatham, Ill-based Micromedical. Balance Quest is a platform that floats on a spring suspension to more accurately mimic natural conditions that disturb proprioceptive information. The suspension mechanism allows dynamic motion of the platform with 6º of freedom of movement. Specifically, the platform can move in three linear planes (forward-backward, side-to-side, and up-down) and along three axes (twist clockwise-counterclockwise, tilt forward-backward, and tilt left-right).

The Balance Quest system includes software that measures center of pressure in the three linear planes plus two of the three axes, which yields a remarkable degree of information about the direction and amplitude of bodily sway as the patient stands atop the platform. This information permits identification of fall-risk factors and aids in assessing whether the patient's balance disorder is due to misinformation or misinterpretation of sensory and motor inputs (plus the extent to which the patient possesses the ability to suppress information that is inaccurate).

IN PLAIN VIEW

Carr believes a standard feature of next-generation gait analysis systems will be virtual reality technology. That will amount to a breakthrough advance for rehab practitioners because, he says, it will help ensure that patients discharged from a highly controlled inpatient environment are truly ready to negotiate the hazards awaiting them in the real world.

"My feeling is that we need to provide more visual stimuli involving everyday things that put the patient's reactions to the genuine test—for example, the act of walking along the sidewalk, coming up to a driveway, and then having a car abruptly pull into it just as the patient is about to step into that driveway," Carr offers. "This is the kind of real-life scenario that is perfect for presentation using virtual reality technology."

Carr works on visual instruction on gait pattern. The client, a stroke survivor, experiences a looping swing phase due to weak hip muscles on his neurologically impaired side. Carr helps the client work on overexaggerating the use of the hip flexors in his gait to strengthen and retrain the proper stride length and right-to-left time distribution.

That level of virtual reality experience remains a ways off yet. Right now, eyes mainly focus on images produced by an array of computer-controlled video or infrared cameras positioned around a treadmill or walkway—the basic configuration of analysis gear in the typical gait lab of today. In ordinary practice, those cameras are trained on anatomical markers at the iliac spines of the pelvis, the malleoli of the ankle, and the condyles of the knee. Signals from the cameras along with data from the treadmill or sensor-laden walkway are then fed into the computer, which calculates the trajectory of each marker and the underlying bone motion. These inputs can be supplemented by data collected from force plates that measure the direction and magnitude of the ground reaction force. From there, it is possible to determine the force exerted by each muscle group and the amount of momentum at each joint during gait.

In the clinical environments where therapists work and perform bipedal in-shoe analysis, many of the most critical aforementioned inputs can be captured with the use of but a single system—the F-Scan® VersaTek. Tekscan of South Boston makes it, and its purpose is to harvest dynamic in-shoe pressure information in order to understand the functional interaction between foot and footwear. Further, F-Scan permits screening for disorders secondary to diabetes or other neuropathic issues, observation of gait abnormalities, regulation of weight bearing after surgery, degenerative foot disorders monitoring, assessment of high pressures due to ray hypomobility, immediate determination of orthotic efficiency, presurgical and postsurgical evaluations, potential ulceration area identification, and regional segmentation of the foot.

Foot-and-ankle specialist Holly Jonely, PT, ScD, COMT, ATC, uses the F-Scan when she needs to manage the foot inside the shoe, increase orthotic footwear performance, and produce better supporting documentation for insurance purposes. She likes its package of electronics, which includes an extremely thin, high-resolution sensor, and the way it all plugs right into her laptop computer. "The Tekscan system is the highest-technology piece of equipment I use in the clinical setting for gait analysis and training," says Jonely, who sees patients at the University of Texas Southwestern in Dallas and at that school's Amarillo Sports Medicine and Orthopedic Center in Amarillo. "About 5 years ago when I first came aboard, I was tasked with responsibility to identify a gait system that would provide objective data sufficient to generate an orthotic prescription," she says. "I decided to search for a system that would look at the interface between the shoe and the foot, then at the interface between the foot and the orthotic. In other words, a system that would look at things before and after an intervention.

"I also wanted a system that would not require my patients to target a single small point on a mat or force plate and have to hit it just right in order for data to be collected. It's problematic to try to hit such a point and at the same time walk normally."

GOES ANYWHERE

Not all force plates represent a utilization challenge. Among the easiest—and most useful—are those made by AMTI. Each of the Watertown, Mass, company's force platform models provides six outputs corresponding to the three orthogonal forces and the three orthogonal moments that act on the platform's top surface when a patient mounts it. AMTI products include BioAnalysis (which performs gait, balance, and power analyses), Balance Clinic (consisting of software for its gait-analyzing AccuSway platform), and Balance Trainer (a visual balance-feedback system).

Jonely, meanwhile, appreciates that her Tekscan system provides objective information about how the taking away of motion in a particular joint affects a patient's gait. "We can determine whether the patient is spending more time or less time taking steps," she says. "With patients who have just undergone knee surgery or hip replacement, we can determine whether they have leg-length discrepancy and, if so, how that's affecting their timing in gait and how that needs to be compensated for. At a minimum, it gives us information about force and pressure across the bottom of the foot. Many of our diabetic clients experience breakdowns in skin integrity—ulcers—and the system provides immediate feedback as to how much pressure is at any given point on the foot. This allows us to make in-clinic modification to the shoe or orthotic, or to prescribe a custom insole."

Jonely carries the Tekscan system wherever she goes. "I'm in the Amarillo clinic every third weekend," she says. "I arrive, set up the system, and utilize it throughout each day I'm there. At the end of my visit, I pack up the system, put it into my vehicle, and take it back with me to Dallas for use in my university-based physical therapy practice."

Tekscan, she adds, makes a wireless version of that particular system. Jonely indicates she would someday like to go wireless because she believes it will give her more versatility.

TECHNOLOGICAL STRIDES

Whatever system one acquires, the best results are seen when gait training is introduced to the rehab regimen as early as possible and repeated as often as possible, Carr contends.

Of course, results are likely to be outstanding no matter what, given the impressive strides being made in gait analysis technology.

"As these system become more sophisticated, our ability to measure will do nothing but improve," Jonely assures. "That's going to be important for therapists like me who specialize in foot and ankle. The foot contains 26 small bones, and there aren't a lot of large motions that occur there. That makes it hard to capture what's truly going on in the foot and ankle. Right now, I'm waiting for analysis technology to catch up to our speculations about what is happening in the foot and ankle."

Jonely expects that gait analysis systems will become more important if medicine in the United States moves in the direction of the socialized models found in Canada and Europe.

"With socialized medicine, more attention is paid to prevention," she points out. "For me as a physical therapist, a shift of attention to prevention might mean looking at ways to screen some of these gait pathologies."

Rich Smith is a contributing writer for Physical Therapy Products. For more information, contact .