The Stance Control Orthosis: Has Its Time Finally Come?

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Bilateral SCOKJ wearer with polio walks in the woods with his dog. Photograph courtesy of Horton's Orthotic Lab.
Bilateral SCOKJ wearer with polio walks in the woods with his dog. Photograph courtesy of Horton's Orthotic Lab.

For years, inventive minds have known what was needed: A free-swinging orthotic joint that allows the knee to bend and flex under the wearer's control rather than locking it into a fully extended, stiff-leg position that made ambulation possiblebut awkward, uncomfortable, and exhausting.

An oft-quoted ten-year-old study claims that approximately 989,000 people wear knee braces. While the same research notes that an estimated 58 to 79 percent of knee-ankle-foot orthoses (KAFOs) are abandoned as ineffective by their wearers, authors of a separate contemporary study also observed that more than 40 percent of KAFO wearers express dissatisfaction with their orthoses even though they continue to wear them.

Clearly the stage has long been set, waiting for the arrival of a talented ingenue to bring salvation and solutions to orthotic patients clamoring for better performance.







That star performer appears to be the stance control orthosis (SCO) and the reviews are unanimously enthusiastic. The SCO recently opened to an audience eagerly poised to embrace itand in its varied 21st century incarnations, it has yet to disappoint.

For years, inventive minds have known what was needed: A free-swinging orthotic joint that allows the knee to bend and flex under the wearer's control rather than locking it into a fully extended, stiff-leg position that made ambulation possiblebut awkward, uncomfortable, and exhausting.

Achieving it has been a long-term challenge, however.

Photograph courtesy of Otto Bock HealthCare.
Photograph courtesy of Otto Bock HealthCare.

Photograph courtesy of Becker Orthopedic.
Photograph courtesy of Becker Orthopedic.

"Stance control orthoses have come and gone in the 35 years that I've been around," reflects John Michael, MEd, CPO, FISPO, FAAOP, an orthotic and prosthetic consultant. "I've seen many through the '70s, '80s, and '90sand none of them were clinically successful."

A stance control knee joint design was created in the Netherlands in 1989 by Nils Van Leerdam, MSc, PhD, at the University of Twente; the UTX was introduced in the United States in 1996 but failed to gain widespread acceptance; likewise, knee joint technology licensed from NASA by Gary Horton, CO, FAAOP, was "so complex we could never get it to work. It was too expensive to follow into manufacture, even if it had worked," Horton says.

Horton developed his own design, working through several versions in seven years before introducing in 2000 the landmark creation officially trademarked as the SCOKJ (Stance Control Orthotic Knee Joint), popularly referred to as the Horton Stance Control.

"My goal," says Horton, "was exactly what we got, something that lets your knee bend through swing and locks at any degree of flexion when you need the safety of it. It blocks flexion but always allows extension."

The SCOKJ was followed by the Fillauer-distributed SPL (Swing Phase Lock), Becker Orthopedic's FullStride" and recently released SafetyStride", and the Otto Bock FreeWalk".

Photograph courtesy of Horton's Orthotic Lab.
Photograph courtesy of Horton's Orthotic Lab.

In 2003, the mechanical designs were joined by the first microprocessor-controlled stance control orthosisthe Becker E-Knee, soon followed by Otto Bock's electronic model, the SensorWalk". Other electronic models are waiting in the wings, to debut soon.

Because they use not only their own componentry but also other stance control knee joints selected by its practitioner customers, Becker Orthopedic has built more stance control KAFOs than any other central fabrication facility, says Gary Bedard, CO, FAAOP.

"Mechanical stance control systems are all gait activated," he explains. "Some component of the gait process locks and unlocks the mechanism, whether ankle range of motion, inclination of limb, or an internal pendulum that matches the limb inclination."

Orthotists choose the appropriate design by matching its mechanics to the patient's ability, says Bedard. "If the patient doesn't have ankle range of motion, obviously you can't apply a mechanical stance control knee joint that's activated by ankle range of motion."

If a patient has very little hip strength, however, microprocessor-controlled stance control knee designs compensate for lost muscle ability.

Other determining factors include cognitive abilities, range of motion, and triplanar skeletal weight bearing as the patient's pathomechanics are matched to the abilities of the stance control componentry.

Keith Smith, CO, LO, FAAOP, Orthotic and Prosthetic Lab Inc., St. Louis, Missouri, appreciates the adaptability that stance control technology offers: It can be used like a standard locked KAFO, "trading up" to the free-swing feature if and when the patient progresses. "They get the best of both worlds by doing that. Patients who have had a KAFO that has been locked for many years know how hard it is to walktheir back [and] hip hurts. This offers them a way to get rid of that pain," Smith says.

Who's a Candidate?

"I'm sure there are well over 100 diagnoses for which SCOs have proved effective," notes Michael. "The problem is it's only a subset of people with that diagnosis. It's not everyone with a spinal cord injury (SCI); it's those people with a spinal cord injury who have a quadriceps weakness or absenceand the ability to propel the leg forward. Thus I recommend that SCOs be prescribed on the basis of biomechanics, what is missing and what can be restored, rather than the diagnosis."

Kelly Clark, CO, clinical specialist, custom orthotics for Otto Bock HealthCare, Minneapolis, Minnesota, agrees that diagnosis is only the starting point for identifying SCO candidate patients. "You can't say it only works for this diagnosis or that diagnosis. How does the patient present, and are they appropriate for the SCO?"

Clark has developed an SCO matrixa useful tool to help practitioners identify features and capabilities of clinically available SCO designs (see table 1 ).

Courtesy of Gary Bedard, CO, FAAOP.
Courtesy of Gary Bedard, CO, FAAOP.

Bedard offers another reference: a retrospective utilization review of UTX stance control systems delivered since November 2002pigeonholed by diagnosis for which they were ordered (see table 2).

Kel Bergmann, CPO, has fitted more than 40 patients with a variety of SCO designs, including an electronic version he characterizes as "not quite ready for prime time...loud, heavy, inconsistent," although microprocessor versions are indicated in cases where patients do not have good muscle strength at the hip, and lack control of the flexors, extensors, abductors, and adductors.

"The device's size and weight play a role," he says. "People with femoral nerve injuries, for examplejust the weight of something dangling on their leg can create a traction effect that becomes painful.

"Success depends on what your patient is really going to do with the device. We've seen some that have come back untouched... The person took them home and didn't use them at all."

Outcomes Studies

Since SCOs have been clinically available for less than a decade, there are no long-term studies of any SCO, notes Michael. Nor are there studies comparing one design to another. The available research concerning the effectiveness of stance control orthoses is encouraging, however, and reports are enthusiastic.

The Role of Reimbursement

Every resource contacted for this story cited reimbursement as a significant stumbling block to the stance control orthosis' progress and proliferation.

"Reimbursement is certainly one of the major variables that determine how much stance control technology is used, and how often it will be considered for a patient," says Keith Smith, CO, LO, FAAOP, Orthotic and Prosthetic Lab Inc., St. Louis, Missouri.

"Since 1968, orthotic knee joints that unlock for swing phase have been considered one of the highest priority developments in rehab. A number of national and international panels have reached that same conclusion. That makes it all the more tragic," says John Michael, MEd, CPO, FISPO, FAAOP, "that Medicare went out of their way to cripple it.

"I don't understand why, but initially they refused to give it a code. The next year they gave it a code that was patently absurd, which was a fraction of the cost of the hardware alone. It wasn't until the third year that they finally gave it a code that was reasonable, but then they gave an allowable that was very low, so basically they choked off the technology for three years, and that is one of the major reasons why it did not take off as rapidly as it was expected tobecause patients were denied access to it."

Clark points out, however, that the unified front presented to CMS was a landmark in O&P history. "It was unique that the manufacturers came together and worked in concert to get a code for stance control. We all converged on CMS to ensure that the SCO technology would be available and affordable to patients who could benefit significantly from it."

Most of the studies used the Horton model or the UTX in approximately equal numbers. General findings were that range of motion during swing phase was much closer to normal with whatever stance control variant had been studied. In every example, the gait biomechanics compared to a locked knee were significantly improved. Most patients had a very strong preference for walking in the stance control mode, noting that it took less effort, or they felt it took less energy to walk in the SC mode.

"The other finding," Michael notes, "was that almost without exception, not only did the motion improve in the braced leg, but the motion of the rest of the body was much closer to normal. So it had a very positive effect on the opposite leg, on the trunk, on the head, on the arms, on the whole locomotor apparatus."

A supporting 2006 study found knee motion increasing with less abnormal pelvic motion.

"That raises the possibility that not only will you walk better, but that you might have less secondary complications as an elderly adult if you're not using all these compensations throughout the rest of your body. I think the results are very supportive and very positive," Michael says.

Kenton Kaufman, PhD, PE, professor at the Mayo Clinic College of Medicine, Rochester, Minnesota, summarizes from his own published studies, and cites others (Amy Gross McMillan, JPO 2004; Jackie Hebair, PM&R, 2005; and Terris Yakimovich, Clinical Biomechanics , 2006). "Collectively, these studies all show improvements in the patients' gait and improvements in their energy consumption; hence, they tend to do better overall," Kaufman says.

Otto Bock's Sensor Walk
Otto Bock's Sensor Walk

Kaufman's 2006 study on consumer opinion showed that the weight and the bulk of a SC knee joint will be acceptable, so long as the functional benefits; i.e., the improved gait, are significant to the patient.

"Many people had previously decided that their locked brace was too restrictive and too cumbersome for them; that's why physicians basically stopped prescribing thembecause patients weren't using them," Kaufman says. "I think now, with this new SCO technology, people can actually use them and be functional and not be restricted in their mobility.

"I think it's important for the practitioner to know that if they see a patient who has used a locked brace, initially the patient may not have as much confidence in their SCO as they had in their locked braceessentially, they have to relearn how to walk with the SCO. A new user who hasn't been habituated to a locked knee will tend to do better initially."

Michael agrees. "It was very clear that the locked KAFO wearers took much longer to adapt to the SC gait than did the novices who received a stance control device," he says. "The prior wearers walked slower, they walked at a lower cadence, and it took six months or longer before they really began to show the benefits".

"Previous wearers have the habit of security; you can't get any more stable than with your knee locked all the time," points out Horton. "Novice wearers accept it better in training because they don't have old habits to break."

Through patient feedback, Horton discovered an added benefit. "Patients really like...being able to walk with the knee bending, which gives them a more normal gait and look, without attracting attention to a limp. There's no real physical benefit from that, but it's a great mental benefit."

Are SCOs Underutilized?

Photograph courtesy of Horton's Orthotic Lab.
Photograph courtesy of Horton's Orthotic Lab.

Just as every source contacted for this story cited reimbursement as a significant stumbling block to the advancement of stance control technology, they also agreed that as a result the technology is not being utilized as it couldand perhaps shouldbe.

Kaufman points out that the strong need and desire of KAFO wearers for a better orthotic solution was dramatically illustrated by the influx of hopeful phone calls from the public, responding to a non-specific mention in a newsletter of the knee brace study in progress.

"They had to really swim upstream to find us," says Kaufman. "Yet we got numerous calls from literally all over the United States and South America."

However, in the face of this eager demand, Bedard notes that in an audience of 500 people at the 2007 Annual Meeting and Scientific Symposium of the American Academy of Orthotists and Prosthetists (the Academy), only 30 percent had any experience in providing SCOs; only 15 percent had fitted as many as five; and only two people had fitted ten or more.

Clark's informal polls have gleaned similar findingsshowing that only 5 to 10 percent of his audiences have fit any SC orthosis, regardless of brand.

"Everybody loves the concept," Clark concludes. "But in practice, I wouldn't say it's been well accepted. We estimate that between 1,200 and 1,600 of these go out a year, extrapolating from Medicare usage figures. Compared with the population of KAFO wearers, that would be way under-prescribed or underutilized."

Why so Few?

"The stance control orthosis is...much more like a prosthesis in that you really need an in-depth evaluation of how the way the patient walks affects the way the joints work," Michael points out. "You need to have them engage and release at the right time in the gait cycle, and there needs to be follow up to maintain the adjustment and the fitting and so on. So it is in many ways a more complex interaction than the traditional KAFOrequiring a greater time investment from a more serious and dedicated orthotist.

"You don't have to be a genius," Michael continues. "But you really need to be serious about being an orthotist because there is a time commitment in the evaluation, in the fabrication, in the fitting, and in the follow up. And that is one of the primary barriers to more widespread use."

Smith agrees. "It requires not only a very involved orthotist...but they're going to need a physical therapist that knows the technology to work with this patient, instructing them and teaching them how to use the brace....

"For eight months I require that the stance control KAFO patient gets physical therapy, and I talk to the PT before we actually go after fabricating the brace for the patient. You've got to educate the therapist in the use of these and how they work."

Kaufman believes that after five years in the marketplace the SCO concept is at last capturing the interest of more practitioners, and given the standing-room-only crowd at his SCO symposium at the August 2007 International Society for Prosthetics and Orthotics (ISPO) meeting, he is no doubt on to something.

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.

Editor's note: The O&P EDGE does not endorse any particular product or service. Product information provided in this article is for reader information only.

Miracles in the Making

The SCO has offered unexpected advantages for the open minded:

Reduced Rehab Time

"Gary Horton has discovered that his SCO knee joint appears to cut rehab time in half for people who have had multiple total knee replacements, and have hence experienced weakened quadriceps function," reports John Michael, MEd, CPO, FISPO, FAAOP. "Their return to work time is cut to one tenth of what it would have been with traditional therapy. The SCO acts as a strengthening device as well as a protective deviceand it's also ten times cheaper.

Return of Function

"We are also seeing a lot of anecdotal reports of spontaneous return of function in the people with spinal cord injury," says Michael. "In case after case, people were told they have a permanent disability, they will never walk again, they need to lock their leg in a brace.... When they went into the Horton's variant, because that particular one allows you to use residual quadriceps function, within 12 to 24 months they were able to walk without the KAFO. Now, none of this has been scientifically studied, but once we see dozens of apocryphal reports like that, we begin to think that there really is something to it."

Stance Control Plus FES

"There have also been some research experiments combining the Horton's stance control KAFOs bilaterally along with functional electrical stimulation (FES) for a person with complete spinal cord trans-section at a very high level," notes Michael. "He is unable to stand unaided, but with the electrical stimulation of his remaining muscles and with bilateral KAFOs, he is able to walk for short distances with the walkerso that has potential research value."


Working with a T-10 level spinal cord injury patient, Smith reported that combining a bilateral SCOKJ with a reciprocating gait orthosis (RGO) enabled the patient to walk faster, more naturally, and more efficiently in the stance control mode, with less upper body compensations (JPO 2007, vol 19, number two, pp. 4247, Aaron Rasmussen, Keith Smith, and Diane Damiano). Additional SCI patients are also being studied, with similar results: more controlled walking, less energy expenditure, all parameters increased and improved. As Smith notes, "Pretty exciting stuff."

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