K2 Ambulator Options Evolve With Seniors in Mind

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By Judith Philipps Otto

As aging baby boomers contribute to the growth of the elderly population, the population  of K2 ambulators also grows, increased by amputations due to vascular disease—and,  consequently, the demand for fresh prosthetic solutions to keep them safely mobile. Such solutions may also include easier accessibility to higher technology prosthetic solutions that have previously been restricted by payers, and available only to K3 and K4 level ambulators. We asked O&P experts to share their insights regarding new options and future possibilities for this K2 demographic.


Exploring the Options

Mike Magee, CPO/L, FAAOP, global education manager, Blatchford US, Miamisburg, Ohio, says that Blatchford recognizes K2 level ambulators as one of the largest populations of people with amputations in the United States. Most sources agree that the numbers are increasing, with some estimates identifying 75 percent of K2 patients as seniors (over age 65).

Attention and interest in Blatchford's K2 products is becoming more focused since the introduction of the Avalon-K2VAC in May 2020, says Ben Auzenne, vice president of sales and marketing,

Blatchford US, who emphasizes the value of the twin benefits of its hydraulic ankle and vacuum suspension system.

"Blatchford introduced hydraulic ankles as early as 2009; it's kind of our flagship," he notes. "We've built a portfolio around hydraulic ankles because we've seen their benefits in numerous studies available on our website."

"The vacuum, the hydraulic ankle, and the foot module are all built into one lightweight biomimetic unit," explains Magee. "The AvalonK2VAC uniquely integrates its hydraulic ankle with mechanical vacuum and foot into a unit specifically designed for the K2 population. The vacuum increases the feeling of socket security, while the hydraulic ankle provides a self-aligning feature regardless of how the patient is standing or walking; it's ideal for most K2 patients. I'm a firm believer—I've seen it work so well for these patients."

Jonathan Cook, CPO, clinical education manager, College Park Industries, Warren, Michigan, says that although the company provided exclusively K3 level Tru-Step feet during its early years, volume-wise they have seen an increase in K2 products, and may now sell as many K2 feet as K3 feet.

The College Park K2 line serves differing activity levels with the basic Breeze and composite Celsus foot with integrated spring. But the Odyssey K2, a hydraulic ankle option, combines the dynamic Celsus foot platform with increased ankle range of motion to enable higher activity in climbing or descending stairs, ramps, or hills. 

"The biggest increase in sales volume has probably been that hydraulic ankle option," Cook says, "which can help to align the prosthesis and stabilize the patient by accommodating and allowing for their movement—which also helps to reduce how much pressure they may be experiencing in the socket."

Justin Pratt, CP, director of clinical education, prosthetics, Össur Americas, Foothill Ranch, California, is aware of varying opinions on hydraulics and the circumstances in which they are applicable within the K-levels. "Our general belief is that once you get into a K3 or K4 level, hydraulics are not ideal in that space. K1 and K2, however, certainly could benefit from a hydraulic unit, as it could make a much smoother rollover in stance phase, requiring less control from the patient and absorbing ground reaction forces. When you incorporate a dorsiflexion spring assist during swing phase, [K2 ambulators] benefit from these devices, as in the DP Flexion, Össur's K2 hydraulic unit, which ensures that they have dorsiflexion in swing so that they can reduce tripping and stumbling as well. Certainly reducing that population's incident rate of stumbling, tripping, or falling is ideal."

Pratt has also observed a rapidly growing interest in offerings that increase efficiency and economy while providing quality product and customer service, such as the Connect TF socket for individuals with transfemoral amputations, an early 2020 product targeted toward low-active K1 and K2 populations. 

"We have been encouraging our customers to understand solutions that minimize contact by reducing the duration of appointment times and the number of appointments," he explains. "Targeted to K1 and K2 individuals who have difficulty donning a prosthesis, the Connect TF's greatest benefit is that it fills the needs of patients who otherwise would not receive a prosthesis due to other comorbidities, thanks to the ease with which it can be donned and doffed. It also significantly expedites care and reduces the risk of exposure and cross-contamination. In addition, we have the ability to provide support and education on a virtual platform."

Another Össur K2 option introduced in 2020, the Balance Foot S, features many ProFlex characteristics, and is now available for the K2 population in a fiberglass material. The asymmetrical toe plate, with the proprietary heel foam, combined with the Pro-Flex Foot Shell, improves gait kinematics and reduces loading of the sound side.

The sole microprocessor option currently classified and available to K2 ambulators comes from Ottobock, Duderstadt, Germany.

According to Andreas Kannenberg, MD (GER), PhD, executive medical director, Ottobock North America,

Austin, Texas, K2 patients in Europe, where K-level or mobility grade classifications influence coverage less strictly than in the United States, have previously benefited from the microprocessor C-Leg developed in the 1990s.

"In Germany, for instance," he says, "you'd do a trial fitting using advanced technologies on the patient, and if you can prove that the patient benefits from the technology, that serves as the basis for negotiating with the insurance provider.

"Clinical studies started in 2005 and 2006, followed by other independent studies including K2 patients, resulted in Ottobock refining a design parallel to the C-Leg, and developing the Kenevo microprocessor knee that more specifically addresses the needs of that K2 population," Kannenberg adds.

One of the unique benefits offered by the Kenevo knee, launched in the United States in 2016, is to recognize when users begin to stand up, and allow them to do so without relying on their sound limbs for balance—something the C-Leg couldn't do.

The ten or 12 studies Ottobock has conducted, involving more than 650 K2 patients, provide clinical support, and some US payers now accept them as a basis for reimbursement on a case-by-case basis. But Kannenberg reports that Medicare has requested stratified studies designed to help predict what share of K2 patients will be most likely to benefit from Kenevo technology—and to identify those likely responders—before approving the Kenevo knee as a K2-appropriate solution.


Evaluating High-tech Benefits for K2 Patients

Gary Wall, MSPO, CPO, West Coast Brace and Limb, headquartered in North Tampa, Florida, has been tracking studies that examine the benefits of microprocessor technology for K2 patients, and advocating for its availability to them. He observes that although the Kenevo knee is the sole microprocessor option currently classified and available to K2 ambulators, other microprocessor knees, designated as K3, could still be used to benefit patients with a K2 designation—and should be, when possible—since statistics reveal that microprocessor knee use may reduce uncontrolled falls by up to 80 percent, as well as significantly improve indicators of fall risk in people with transfemoral amputations who are at the K2 level. Studies continue to support findings that K2 patients' Medicare functional level after accommodation to the C-Leg improved to K3 levels in some cases.

Cook observes that "most amputees fall at some point, and anything we can do to reduce that possibility reduces the likelihood of a trip and fall accident and all the trauma and pain that goes along with it."

Magee agrees, and encourages asking the K2 population about falling. "Ask them about their confidence," he says. "Their number one fear is falling."

Magee points out that not all people with amputations aspire to climb

Everest or run races. In the K2 population especially, their goals may be less visually spectacular but no less important—to walk through their homes, to stand in the kitchen and cook a meal with their spouses, or perform other daily tasks.

He describes someone with a bilateral amputation whose primary goal is to be able to walk smoothly enough to deliver a full cup of coffee without spilling it.

"Little things like that matter to K2 patients," Magee says. "Quality of life isn't necessarily about running races. Maybe it's as simple as being able to trust your prosthesis."

Wall amplifies that "if you have an amputee who undergoes a fall, especially a traumatic one that leads to injury, it's not only detrimental because they hurt themselves and have to seek medical care and rehabilitation, and deal with their costs; it's also psychologically damaging. They start to second-guess themselves; they get nervous; they don't trust the prosthesis."

Brian Kaluf, CP, FAAOP, Ability Prosthetics and Orthotics, headquartered in Exton, Pennsylvania, points out that although evidence of potential cost savings from avoiding falls seems to be convincing, "The evidence doesn't exist—especially in K2 populations—that microprocessor ankles have been demonstrated to avoid falls or reduce the evidence of falls. Hypothetically, if a microprocessor ankle does improve the balance and reduce incidence of falls in K2 ambulators, it could be an economic argument—although Medicare, in my understanding, does not look to healthcare economic evidence to dictate coverage criteria. They look at medical necessity and what is evidence based."

Kaluf's 2017 study, "Hydraulic and Microprocessor Controlled Ankle-Foot Prostheses for Limited Community Ambulators with Unilateral Transtibial Amputation: Pilot Study" was inspired by similar studies that focused on providing microprocessor knees to people with transfemoral amputations classified as K2 ambulators.

"We saw mixed benefits in our single subject across a variety of types of ankle-foot mechanisms, even including hydraulic ankles without microprocessor controllers—but other research evidence of their benefit for the K2 population was also quite sparse. I definitely would not consider the results conclusive," he notes.

Auzenne points, however, to findings from the 2020 study, "OASIS 1: Retrospective analysis of four different microprocessor knee types," that compared K3 level knees' capabilities to reduce injurious falls. "The study cites that basically one in three patients that are on a mechanical knee will have a fall with regularity. And not just any fall, but an injurious fall."

"We need large-scale grants of the Oasis size for better efficacy," Wall agrees. "More and more grants like that are needed, more studies."

Cook also stresses that progress toward approval of microprocessor knees and ankles for K2 patients will rely on evidence-based practice. "One of the benefits of O&P education moving to a master's degree a few years ago is there's a lot more research being done on the efficacy of these technologies," he reflects, "and on confirming clinical benefits to patients at the lower ambulatory levels for the higher reimbursement products."

Although several contributors noted that there are occasions when a K2 level patient might be covered for a microprocessor, most agree that such occasions are rare.

Pratt notes that "Össur educates clinicians on reimbursement policies, how to navigate a claim, what attributes from that patient they need to incorporate so the payer understands the bigger picture," and encourages support across the board in advocating for K2 patient coverage in the face of denials if the practitioner believes something is appropriate for the patient.

"We need practitioners to align and support each other and the various manufacturers as well, because that's a fight the manufacturers likely won't win alone. We've had payers deny us an opportunity to interface with them directly to teach them about the products and how they contribute to patient outcomes," Pratt says.

Ironically, however, Wall points to the downside of such interactions, from the clinician's perspective: "If you have to submit your case for review to a payer instead of using a lesser technology, you may be delaying patient care on the strength of a gamble. Is it worth the effort to go through a long, arduous appeal process in order to possibly get your patient on a better first prosthesis—or do you limit them to mechanical componentry, hoping (or until) they reach K3 status, which we know often doesn't happen? That's the Catch-22 right now."

We are learning more every day that gives us hope, however, sources confirm. Kannenberg hints that, when making the case for higher technology on behalf of K2 ambulators, we may soon be able to look beyond the traditional benefits concerning safety, reduced falls, and better mobility. "We have some indication that K3 technology that is used in K2 patients may have additional benefits that we haven't thought of yet—such as treating knee and back pain. That could become part of the equation when we negotiate with Medicare and private insurers in the future."

Is the Best Yet to Come?

Tom Nomura, CPO, director of clinical services, Proteor USA, Tempe, Arizona, says that "we are currently seeing an increase in features that are trickling down from componentry that would typically be used for higher functional levels that are adapted specifically for the K2 user.

"We are making progress," he adds. "As the body of evidence-based studies increases, it will be increasingly difficult for payers to overlook the overall benefit to both the user and the decrease in long-term healthcare costs. I would expect a balance between both high-tech and lower-tech solutions will be pursued in the future to address the needs of the K2 ambulator."

"Ottobock is also working on feet that are a little more dynamic than the typical K2 feet—still keeping them within the codes that K2 patients have access to," Kannenberg says. "You have to be very careful when developing a foot, that you can still apply the K2 codes, yet provide a little more dynamic behavior of the foot."

"Even outside of P&O, businesses and people want their products and services expedited," observes Pratt. "They want them quicker. They want them easier to use. Össur is now looking at exploring and expanding on various technologies. The Direct Socket, for example, is a technology appropriate for the K1 through K4 population, available for transtibial and transfemoral applications. It's an ISO-rated socket to 365 pounds, and for a transtibial, you can effectively fit and deliver a custom, total contact fit socket in one visit, expediting care and having consistent, positive results. For the transfemoral, it's more involved on the time aspect, but it's still a one-visit process to delivery...."

"Wouldn't it be ideal if you had a patient who is a K2 ambulator today, but had the potential to move to a K3, and they had a prosthesis that could grow along with them?" Auzenne wonders. "Innovation takes all forms, and Blatchford is constantly pursuing such avenues of innovation in our purpose and vision to create the future of mobility rehabilitees and help people realize their dreams."

"We're always looking to fill out our portfolio," Cook says. "We currently don't have a microprocessor foot on the market, and many of our competitors do. So regardless of the level, whether it remains where it is as a K3, or if there's an option at the K2 level for a microprocessor product, I think College Park would have interest in developing an option in that area."

"We can't comment on future microprocessors for the K2 population," says Pratt, "but Össur is persistent with our innovations and with our approach to supporting this profession as a whole. We are actively engaged with seeking out new designs, new coding structures, revisions of codes, and so forth."

It takes a village. Auzenne is passionate in his conviction that change to improve the menu of options available to K2 patients—including access to microprocessor componentry—can best be achieved through an industry-wide effort, including manufacturers, clinicians, advocacy groups, and professional organizations, all working in concert. "It's important that we stand together and collaborate on opportunities to demonstrate the economic benefits of treating these patients with higher technology that allows them to live their lives.

"It's been 28 years since we've done a comprehensive study in the US on the amputee population. Isn't it time we did an update?" O&P EDGE


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.