Microprocessor Tech: Still Driving Change

Since the 1997 appearance of the C-Leg, microprocessor knees (MPKs) and, later, microprocessor ankles/feet, have been making news. Like ripples in a pond, their impact has not only altered the lives of people with lower-limb loss and changed the way O&P professionals provide care, but as new technology evolves in these areas, fresh waves add to the energy and fuel further evolution. The O&P EDGE asked experts how these types of prostheses have evolved and how they’re influencing patient outcomes and the business of O&P. Early History In its early days, the C-Leg was widely touted by the media and even captured the attention of the general public with its capabilities—and the brighter futures it promised for wounded warriors returning from the Persian Gulf wars. “At the time, the highest-tech comparison was the hydraulic knee, a byproduct of the 1950s; it was like comparing a Model T Ford to a Corvette Sting Ray.” recalls Frank Snell, CPO, FAAOP, president and CEO, Snell Prosthetics & Orthotics, Little Rock, Arkansas. An early adopter of the new technology, Snell served on a 2003 panel of physicians, therapists, manufacturers, and prosthetists who made a two-day presentation to the administrative staff at Walter Reed Army Medical Center, addressing the advantages of MPK technology. The US Army and the Department of Veterans Affairs quickly embraced the new technology for their veterans, and consequently, Medicare supported the federal program by accepting and giving MPKs a place in the coding system, which opened the gate to coverage for civilian patients who qualified for the technology, as well. The catch, Snell explains, was the price tag. “Just prior to the C-Leg’s debut, a state-of-the-art above-knee prosthesis might cost between $20,000 and $25,000. A microprocessor doubled or even tripled the cost of that prosthesis. Not only did the cost put it beyond the reach of many patients, but it heightened their expectations that the revolutionary knee was practically going to walk by itself.” Fitting an MPK patient was also considerably more challenging in those days. Aaron Sorensen, CPO, owner and president, Restorative Health Services Group, Murfreesboro, Tennessee, recalls that his first C-Leg fitting required him and his patient to fly to Minneapolis and stay for two or three days. “Now it’s nowhere near that kind of education and training that we had to do as prosthetists and patients; and now, too, the payer side gives us an easier road map to get these devices approved for reimbursement.” Although not everyone was a candidate for an MPK, reputable companies quickly recognized that when used appropriately, the technology provided a superior tool for their higher activity patients, Snell points out. “They did not make K3s out of K2 amputees, but they certainly offered a level of function that was never before possible.” The C-Leg’s capability for catching stumbles, preventing falls, and maintaining stability descending stairs was even more widely recognized in the New York Times on January 3, 2002: When the Twin Towers were attacked on 9-11, a C-Leg wearer safely descended stairs from his office on the 70th floor, step-over-step—without delaying others fleeing the doomed structure. Professor Sir Saeed Zahedi, OBE, past technical director now advisor to Blatchford, headquartered in Basingstoke, United Kingdom, notes that “first-time prosthesis wearers initially had to be taught how to fall safely wearing an MPK, whereas conventional prosthesis wearers were already used to falling 100 times in a few months; they assumed that falling was part of being an amputee. That’s horrendous!” He reports that MPK sensors captured evidence of 100 times more stumbles than were reported by MPK wearers—who identified only two or three falls per month and were unaware of the many stumbles that had been averted. Providers continue to offer anecdotal evidence of life-enhancing if not life-saving experiences from their own MPK patients, contributing to a growing body of evidence documenting the case for medical necessity based largely on the stumble response and fall prevention aspect of the devices. Abundant reports come from patients like the MPK wearer observed by Walter Governor, area director, Central and South Texas, Hanger Clinic, headquartered in Austin, Texas. “After 12 surgeries, this gentleman was told by doctors that he would never walk again. With the new technology, he had risen from his wheelchair, was standing at the top of the stairs, and broke down in tears as he prepared to descend the stairs, step-over-step.” What’s New? Today, the prosthetic practitioner’s challenge is not so much whether to fit a patient with a microprocessor device, but which one to choose, Sorensen notes. “It’s no longer one-size-fits-all; there are many different devices and functions, and some manufacturers even offer multiple microprocessor knee designs.” Snell agrees that with so many options available for lower-limb patients, fitting becomes a question of what scope of microprocessor technology to offer the patient. “That’s kind of a tricky issue—because I’m not aware of any studies that advise when one model works better than another, and under what circumstances and conditions.” “Today’s MPKs are coping with the environment more accurately and more reliably, navigating ramps and stairs safely because they are adapting to the user more accurately,” notes Zahedi. “And because they are using new microprocessors, they are faster, and they have a longer life on the battery and sensors—therefore their quality is better. They last up to five to seven years longer, so they are also more sustainable for the payers.” While the focus had previously been on MPKs, says Zahedi, Blatchford recently demonstrated that “adding a hydraulic ankle, with foot-and-ankle compliance with the ground, actually reduces the load on the knee, and the stability is helped significantly by having an ankle that adjusts to the slope of the ground. Without the hydraulic ankle, prosthesis users walking down a slope have to hold onto the walls; with the hydraulic ankle, they can walk independently and confidently. [caption id="attachment_241409" align="alignright" width="97"] Linx[/caption] “One of the surprises that we discovered was the ability of the ankle to sense the environment and dictate to the knee what to do,” Zahedi explains. “The level of stability at the knee comes from the ankle, and the amputee’s comfort depends largely on the interface forces initiated by the ankle and foot during walking, sitting, and standing.” “The old Adaptive (later Orion) Knee and then the Linx Lower Limb, which combined the knee and ankle, reduced weight with fast servo valve control to stop buckling,” notes Zahedi. He estimates that nearly 50,000 people with lower-limb amputations benefit from this reduced risk of falling, with the added benefit of eliminating the need to train Linx wearers how to fall. Orion recently improved stair descent recognition and stance flexion, while the Linx is the world’s only fully integrated limb. As such, the Linx mimics the human leg by actively sensing and analyzing data on the user’s movement, activity, environment, and terrain, providing a coordinated stream of instructions to the hydraulic support system for a more natural walking experience. PROTEOR’s Quattro Knee was introduced in September 2021. Where previous models had limited valve diameters in the hydraulic knees, Quattro can adjust to any previously in-between diameter, says Sarah Stilley, MS, MSPO, CPO/L, clinical prosthetist, global leader, Ankle Portfolio and Clinical Communications, PROTEOR, Tempe, Arizona. The precision allows the knee to behave more reflexively, depending on conditions—like an anatomical knee, she explains, with a similar level of proprioception. [caption id="attachment_241405" align="alignleft" width="143"] Quattro[/caption] “The patient doesn’t have to adjust to the leg’s walking pattern. It adjusts itself intuitively to the patient’s natural gait,” she notes. “Where prosthesis wearers usually tend to look at the ground to watch where their feet are going, we tell Quattro patients to look up at their surroundings and trust the intuitive response of the knee.” The difference lies in the three sensors Quattro employs, rather than a single baseline load sensor; the additional sensors measure the angle of knee flexion and track acceleration and orientation. “Its patented real-time control technology is the first and only technology like it in our industry, able to sense and respond to make adjustments within five milliseconds—faster than our brains can apply thought to action…,” Stilley says. One of the highlights of this knee is that it affords separate resistance for stairs or ramps—independent of the resistance setting for sitting/standing. Another is its app-based programming, including a patient app that allows users to select 20 different modes and features–and an ability to store and send statistical data essential to tracking patient outcomes. Ariel Cabana, CPO, senior clinical specialist, Lower Limb Prosthetics, Ottobock, Austin, points out that the C-Leg is still the standard of care from which their family of MPKs have all evolved. As technologies in cell phones, aerospace, and other industries have evolved, Ottobock tech has integrated borrowed advances like gyroscopes, accelerometers, and autopilot—which take the form of multiple sensors in addition to the two with which the C-Leg was originally introduced. As a result, the features and functions that the C-Leg 4 boasts include more inputs from the environment, plus real-time gait analysis that makes it react faster and more intuitively for the user, Cabana explains. “The C-Leg itself is still the most studied microprocessor knee out there—and fall prevention is a key aspect research has focused on. It’s a major concern from the perspective not only of health insurance and prosthetic providers, but also of the end users, who benefit from newly enhanced stumble recovery that makes it even safer throughout the entire phase of the gait cycle,” she notes. “Those benefits really apply to their activities of daily living, as well.” The C-Leg 4’s standing function allows the user to bend the knee to a desired “relaxed” angle during standing tasks like washing dishes, while its weather-proof IP67 rating allows for limited freshwater submersion. Additional modes also allow users to customize their C-Legs by programming extra features that make them more specific to their interests. Since all MPKs have to be programmed, the prosthetist also needs to learn how to program and optimize the software for the user, she adds. “But we’ve really tried to simplify that process, with easier and more intuitive programming, with less option for error than the original—so the C-Leg is prosthetist-friendly as well as user-friendly.” Kurt Gruben, CPO, senior clinical specialist, Prosthetics, Össur Global Academy, Orlando, Florida, notes the advent of motorized technology in knees and ankles as early as 2007, only ten years after the C-Leg appeared. “The first powered knee was quite large and heavy but assisted in lifting activities and in swing phase; motorized technology was then also applied to help pre-position an ankle for weight bearing, and initially gave active muscle power during stance with toe-off energy in what is now the Empower Foot,” he explains. Ottobock identifies it as the only commercially available microprocessor foot with powered propulsion. Össur acquired the Power Knee technology in 2007 and improved it for a 2010 second-generation debut. A power knee L-Code was awarded in 2012 and is still valid for the current third-generation Power Knee, released in 2021. The power knee replaces lost motor function with a motor, explains Justin Pratt, CP, director of Clinical Education, Prosthetics, Össur. “Currently, there’s nothing else readily available on the market to provide that power assist for stair ascents, getting out of a chair, and gait flexion and extension; that’s something that’s been elusive, across many prosthetic designs and devices. “This latest generation is remarkable in comparison to its predecessor,” he notes. “The sensors have improved, we reduced the weight again, we increased battery life, we made it quieter. With the functionality in the knee, and the improvements in the programming, and the sensors that are on board, we’re now able to fit a much wider population who, with motor-powered technology, can enjoy powered flexion and extension and a normalized biomechanical gait—which is very different from a passive prosthetic gait.” The learning curve has also been reduced considerably due to the technology and the firmware and software in the latest version of the Power Knee. “With the recent version,” Gruben agrees, “one of the very distinct differences is in the algorithms used—the way it’s programmed. The Power Knee matches how the patient walks, and then immediately delivers the benefits of power. But it can accommodate to different gait styles very readily, so it makes it very easy for a new user to realize its benefits very quickly, instead of trying to figure how in the world they’re supposed to walk to make this thing work. It’s more intuitive in that way.” [caption id="attachment_241406" align="alignright" width="121"] Power Knee[/caption] The Power Knee’s ability to not only prevent, but rescue from stumbles, make it an attractive potential candidate for K2 level patients, as well: When it detects resistance from headwinds, power cords, snow or tall grass, power extension allows it to push through those obstacles to make sure the knee is extended so users land on their feet—something no other MPK can do, Pratt adds. “That same power extends the knee to push them upright and stops falls before they go beyond a stumble. “We’ve seen K2-level amputees, especially with this new device—evolve out of a K2 and progress into a K3. Now they’re more mobile—they get out of a chair easier, they notice they don’t need a cane now, energy consumption decreases, their stability improves. Some even report reduction in back pain medications,” he says. Össur also offers an adaptive microprocessor-controlled ankle—the Proprio Foot—for low to moderately active users, designed to improve safety by increasing toe clearance in swing phase and adapting to changing terrain. The ankle also has its own L-Code. What’s Changed? The new microprocessor technology not only offers a greater variety of better, faster, lighter weight choices to improve patient satisfaction—and their lives overall—but also impacts the way practitioners do business, practice owners report. Patient welfare and satisfaction Both are improved with microprocessor technology. “Their own stories tell the tale when patients have been in a traditional mechanical knee and we’re able to put them into a microprocessor knee,” says Sorensen. “Through the first six months to a year, they describe their activities, accomplishments, their distances, and their new ventures—how they’re doing more, fatiguing less, experiencing fewer falls. That really helps to drive home that as prosthetists, we’re really making differences and changes in a lot of people’s lives.” Snell points out that the amount of control and function in today’s microprocessor devices is greatly improved over the level of the 1997 C-Leg. “Although patients may not have much to compare it to if they’re a new amputee and have never worn an older style, once they’ve been fit with microprocessor technology, they’re seldom satisfied to have anything less.” Even patients who are experiencing an MPK trial or demonstration react strongly, sources say. “If they’re doing a demo on the Power Knee,” Pratt says, “and we try to put them back on their passive device, most commonly they ask not to have to leave the facility with their existing device; they want to know if they can keep the Power Knee that they wore during the demonstration.” Patient-personalized technology “Using sensor data from these devices, we’re able to learn that the amputee does more sitting to standing or standing to sitting than actual walking, for example,” Zahedi reports. “Such a biography of the activity of an individual amputee allows us to better match the device to the knee to ensure the amputee’s comfort and stability.” Sorensen cites patient involvement and control as one of the biggest game-changers MPKs have introduced to patient care. “Some of the newer knees and to some degree, even the microprocessor ankles, have an interface on their mobile phones where the patient can a tweak a few things to personalize their device. Many patients appreciate an application that allows them to have to some control over adjusting and fine-tuning how their MPK works.” New approaches to patient care by better educated and prepared clinicians Governor notes that microprocessor technology has become a standard of care for the 12 clinics within his region. “Since there are now a variety of knees with different functions, different features, we don’t limit our clinicians—we encourage them to select a device that’s most appropriate for the patient. “Not only has it expanded who we might be able to provide devices for because of some of the features and benefits of this technology, but it has helped elevate the skill sets of our clinicians in the industry overall. It has enabled them to have conversations with patients about their goals and desires, and to choose from a wider array of options to help them optimize outcomes and achieve those goals.” Pratt observes that prosthetists are changing their way of thinking, and reversing previous norms: “In the past, the mindset has been, ‘You demonstrate to me why I should put you on a Power Knee.’ “We’re starting to see a shift where practitioners say things like, ‘I’d put everybody in an MPK if insurance would allow me. They’re safer in an MPK and there’s a lesser risk of them falling.’” Stilley sees the same change in practitioners’ approach to making a fitting choice: “The ideal approach for a prosthetist is to see a patient and determine what will enable their best outcome. Now, I think they start by first considering a microprocessor solution, if possible, and rule it out if warranted, rather than only considering a MPK device in rare special cases, as was once the norm.” Better partnerships with manufacturers Snell reports that manufacturers are very willing to let practitioners trial a knee or a knee-foot combination in order to evaluate a patient. “We often do clinics where patients can come in and trial a product without any level of obligation on their part.” Sorensen agrees. “I have not come across one of the manufacturers yet that hasn’t been very accommodating when we’ve reached out and asked to do a test drive with a patient who is an MPK candidate. Now I can call them and quickly have both the knee and the area rep in to work with us and the patient. So that partner relationship has also developed.” Since early MPK technology was so extraordinary, that it had to be seen to be believed, Gruben agrees that such trialing was essential. “That definitely changed the way people approached the field. In some areas of the world, an extended trial would allow a patient to better understand how this technology would help them in their daily lives.” What to Expect “Prosthetic businesses have the challenge of getting the products authorized, paid for, and be able to survive inspection audits once the device has been delivered—so there’s been a certain level of risk, but yet, there’s been a financial reward to it as well,” Gruben reflects. “Today, one cannot stand without it. You have to be able to offer this technology in order to be a leading prosthetic facility. You can’t ignore it because patients are now coming in with internet-printed data and asking if we can tell them about it. Then they start telling us about it,” he laughs. “So you’d better be informed, and be prepared,” 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. Has the MPK Evolution Worsened Reimbursement Woes? "The early MPKs had to be invoiced using an unlisted procedure code,” Snell remembers. “And insurance companies—particularly in Region C, where I practice—would not pay for any unlisted procedure codes without a ton of documentation. Even then, anticipating payment was very, very risky.” Now, he says, “Microprocessor technology is certainly the gold standard for those patients that have the proper K-level and documented need, and prior authorization has become the standard now for all third-party payers. I don’t have a problem with that; I would much rather have authorization and then proceed, than to fit a patient first, and then be denied.” Linda Collins, director, Reimbursement Strategy, Össur Americas, explains that certain new high-technology products don’t have a code because they don’t fit into the existing codes. “Payers, Medicare being one of them, seem to have a hard time grasping that concept—and often make someone who is billing a miscellaneous code turn in all sorts of documentation, invoices, etc., so they can figure out what it is. It certainly is a deterrent from trying to use new high-end technology for patients.” Partnering with the manufacturer is always in everyone’s best interests, she says. “If you’re using a product that is coded with a miscellaneous code, be sure to check with the manufacturer of the product for any resource that they have to help you bill it. “You have to submit a description of the product and the manufacturer should have that all ready for you,” Collins says. “That makes it a bit easier for you—so you don’t have to recreate the wheel.” Cabana notes that the C-Leg and Kenevo, like most other MPKs, have standard coding, but the Genium and X3 knees require miscellaneous coding. “We’ve applied for coding, but it’s a long process,” she notes. Proper documentation as well as end-user self-advocacy is the key to reimbursement success in these cases, she advises. “Fighting the fight, [and] constantly appealing denials makes a difference. There are certainly private payers that have paid for all of the above.” Collins concurs. “I do know that people who are willing to fight—push back a little bit—usually get approved. I see that more often than not. So that’s why I always encourage people to take on the good fight.” Manufacturers do assist with reimbursement problems. Snell says that each manufacturer not only has descriptions and functional data specs on their products, but also some outcomes measures, “and they’re glad to share this information with any retail facility in order to get prior authorization to fit their microprocessor devices.” Because of the environment with reimbursements, Ottobock offers several forms of reimbursement support, including doing all the billing for the provider, who then receives a fitting fee from Ottobock. Free support is available for appeals and claim verbiage, and Cabana offers a “Reimbursement 9-1-1” email address. To request assistance, email ottobockreimbursement@ottobock.com . “We do try to partner with businesses that may be reluctant to try these components because of reimbursement concerns,” she says. Pratt describes an informational reimbursement workshop he and Collins brainstormed years ago—which has evolved into a cost-free customer support platform within Össur that provides mechanisms and resources. “The reality is that without reimbursement, income won’t come to anybody—not to our customers and not to us—and it won’t advance our R&D,” he adds. For tools or to subscribe to the reimbursement and regulatory services blog, Össur R&R, visit ossur.com/en-us/professionals/ossur-rr . Stilley shares that most clinics are comfortable with the improving reimbursement situation, as Medicare’s processing of claims has improved. Quattro components are covered by six recommended L-Codes that are PDAC verified. “We also partner now with the professionals at O&P Insight to provide reimbursement support at no charge to PROTEOR customers,” she says. For help, call the reimbursement support hotline at 855-966-1691 or visit proteorusa.com/reimbursement . Sorensen notes that the evolution of microprocessor technology has fueled payer acceptance, as well. “Because it’s been 25 years and there’s been so much data from usage, it’s getting easier for patients to be able to get this technology if it’s warranted. We’re finding that if the patient is truly a candidate, and we have the proper documentation, we’re not having a difficult time to get that patient this kind of technology for their care.” Snell also notes that while his clinicians advise patients who are choosing a third-party payer, “Medicare is not the demon that a lot of people think it is, and their prior authorization requirement has not panned out to be that much of a problem in my practice. We get our documentation, we submit it, Medicare has ten days to get back with us, so it’s just an additional ten-day step. “The few times we’ve gotten a denial, we submitted the additional documentation that they were looking for, and we’ve gotten approval. So nobody’s doing without,” he concludes. Gruben agrees that as MPK longevity is established, and as manufacturers increase the types of technology, such as adding power, “we’re getting recognition for that, as well, through Medicare—where a powered MPK code has existed since 2013. So a couple of those reimbursement barriers are already passed. I think we’re in great shape there. “The big insurance companies are generally following suit with that, but yet the qualifications and the stringency with policies is becoming more and more challenging for the prosthetists across the country to deal with. I think we’re going to see continuing challenges as the technology grows, where the current coding system may not be able to fully encompass newer technologies, and so we have to be creative with how we move forward with that as well.” Collins also warns, “I do not see the reimbursement situation improving. I think it’s maybe getting worse. The payers are getting pickier about what they’re looking for. We’ve heard certain payers randomly or routinely just deny claims—and people have to really fight to get the coverage. “I advise people to be sure to read the coverage policies of the payer and give them exactly what they want so it’s hard for them to find a reason to deny. Just understand the medical policy—that’s the most important thing I can tell people.” Image courtesy of Ottobock. Quattro Knee courtesy of Proteor. Linx Lower Limb courtesy of Blatchford. Power Knee courtesy of Össur. Money image: Ira_Shpiller/stock.adobe.com

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