The Weighty Challenges of Bariatric Care

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By Judith Philipps Otto

The world is changing, and with it, the profiles of those who need prosthetic care: More than three million new cases of obesity are reported annually in the United States—a condition shared by 31 percent of adults, according to 2018 reports. Those findings are also reflected in O&P patient demographics, according to industry leaders who report increasing numbers of overweight or obese patients who present a new array of challenges to those committed to providing successful outcomes and positive patient experiences.

Bariatric, Obese, or Overweight?

While authorities are divided on the clinical definition of morbid obesity, with some identifying it as an excess of body fat, or weight of 100 pounds over ideal body weight, and some as a body mass index (BMI)* higher than 35 or 40, most agree that the term "bariatric" pertains to the study, prevention, and treatment of excess weight in general, including surgical options.

While experience is making clinicians more proficient at caring for overweight patients, Kevin Carroll, MS, CP, FAAOP(D), vice president of prosthetics, Hanger Clinic, headquartered in Austin, Texas, says, "It's the very large people—400-, 500-plus pounds—that present challenges, even in the terminology we use. I avoid judgmental terms, like grossly and morbidly obese, that can have a negative impact on those who are overweight."

"We're definitely seeing an increase of heavier patients at all levels," agrees Frank Snell, CPO, FAAOP, Snell Prosthetics & Orthotics, Little Rock, Arkansas. "Morbidly obese patients account for about 10 percent of our business. Prosthetic componentry used to have two weight limits—150 and 220 pounds. Now it seems like 300 is the new 220."

Jim Colvin, director of research and technology, WillowWood, Mt. Sterling, Ohio, confirms that most of WillowWood's components once had a weight limit of 250 pounds, but increasing demand prompted the development and release in 1997 of their Magnum line of components for people with lower-limb amputations, with its expanded weight limit of 350 pounds.

Since then, "We've expanded our offerings in the Magnum components for those up to 350 pounds," he says, "and now we develop products with that weight limit in mind."

A Growing Market

The reasons for the growth in patient girth and consequential bariatric demand for O&P care are complex and varied, ranging from greater caloric intake and less physical activity to lack of sleep, stress, side effects from medications including antidepressants, steroids and other drugs, genetic predisposition, eating disorders, and other medical conditions.  

"Take a person who may be large to start with, add in an amputation, and now they're even less active than before," Snell points out. "And for some of them, eating is a form of self-medication. The more they eat, the larger they get, and the spiral just grows."

Jack Lawall, CPO, Lawall Prosthetics & Orthotics, headquartered in Philadelphia, agrees. "Many patients are aware that their amputations are due to complications with their diabetes, neuropathy, and infection, and their inability to heal chronic wounds. Usually, their doctor will advise them to stay off their feet if they have a sore on their leg or foot—and when that happens, they tend to gain weight and become more deconditioned due to their battle for limb salvage."

Lack of mobility will add to an individual's weight. Carroll points out that some heavier patients may also lack the financial resources to pursue a supervised exercise regimen or a healthier diet. "There are patients who will not have the resources to be up and mobile, to get to a gym and work with a personal trainer—many are lucky to be able to get out of their houses."

Michelle Hall, CPO, FAAOP, Gillette Lifetime Specialty Healthcare, St. Paul, Minnesota, agrees that in many ways, the deck is stacked against extra-large patients, even those whose height and stature accommodate greater weight and utilize it in active pursuits. She cites the case of one of her patients profiled in The Academy TODAY's  Winter 2013 issue—a complex case where a 60-year-old, 6 foot 9 inch man who weighed 446 pounds (BMI 47.8) suffered a knee dislocation resulting in a permanently unstable knee that ultimately led to a knee disarticulation amputation.

"There were multiple medical issues: They didn't take an x-ray because he was too large to be on the x-ray table; vascular surgery refused to do an amputation because they thought it would fail. There were multiple impediments in this case that never would have happened if he wasn't morbidly obese."

Even custom solutions aren't always available for larger patients. Hall recalls an attempt to spare the patient the onerous experience of being casted by asking a manufacturer to fabricate a socket from measurements. Unfortunately, once the measurements were provided, the manufacturer discovered that their computer program had a limit on the size of the numbers that could be input to make the socket, and they were unable to complete the job.

Some O&P practices may elect to serve fewer of these challenging patients, in part because of the additional overhead costs involved, including extra time and effort. Hall says that "everything tends to take longer—casting the patient takes a bigger cast, and additional buckets of plaster to fill it—which requires additional mixing time. The larger surface area takes longer to modify, and it takes two technicians rather than one to fabricate the check socket or laminate—and transporting it requires a wheelchair."

Snell notes that because many of these patients were not previously active, and are even less active after amputation, added operational costs include adaptive wheelchairs and bariatric walkers, as well as bariatric furniture in exam rooms and waiting rooms.

Combining these considerations with the higher cost of hard-to-find heavy-duty components (which are often non-reimbursable) lead some to conclude that the cost to the prosthetic facility to treat a morbidly obese patient is prohibitive.

Challenges to Fitting the Bariatric Patient

Component Availability
Many practitioners have difficulty locating the components needed to safely fit a patient weighing 400 pounds or more.

"Seal-in liners are available up to 55 centimeters," Snell notes, "but we've had patients who were significantly larger than that. When you can't get a liner on a patient, it compromises your attempts for a successful outcome."

Eric Schwelke, CPO/L, director, Kessler Prosthetic & Orthotic Services, Livingston, New Jersey, solicited recommendations on the OANDP-L listserv for a weight-activated locking knee for a 6 foot 2 inch, 360-pound male patient with a K2 designation, but received few suggestions that offered relevant candidates.

There are some options, however. These suppliers were mentioned by one or more of those we talked with for this story:

  • Bulldog
  • Kingsley, makers of a SACH foot rated to 500 lb.
  • Freedom Innovations, makers of a foot with a 500-lb. weight capacity
  • WillowWood, Magnum heavy-duty devices and liners
  • ALPS, makers of liners that fit people up to 500 lb.
  • TiMed – BK500 and AK500 systems, pylons, polycentric knee, manual lock with a 500 lb. capacity
  • MakStride's custom K3 is rated up to 500 lb.
  • Össur provides custom feet for larger patients
  • Ottobock's Terion K2 foot is rated to 385 lb.    


One reason for the scarcity of components and systems rated for more than 400 pounds is the absence of an International Organization of Standardization (ISO) standard against which such systems can be tested.

Colvin says that WillowWood has considered developing an option above 350 pounds but is not presently pursuing it. "One of the things that WillowWood has been working on with the ISO standards committee is developing higher weight limits for component testing. Currently the highest category that's being included in the standards is what we call P8—which is roughly 385 pounds. At this point, there's no good guidance above that for people that need something that's even heavier. So it's tough for manufacturers to be able to test components and say they're appropriate for a higher weight limit if there are no standards available to guide them."

He explains that efforts to develop products designed for patients over 400 pounds would require new standards and equipment for mechanical testing of greater load levels, and to identify appropriate candidates and arrange clinical tests of new products. This process could take years, he speculates.

Another reason is simple economics.

"It comes down to whether it's financially feasible for a company to make products where the market is so small," says Snell.

That's a question that troubles manufacturers, as well.

Vladimir Radzinsky, MSc, MWe, inventor and president of TiMed, Torrance, California, says he asked himself if he really needed to create a new system that was expensive to manufacture and would sell barely enough pieces to cover the cost. "Everyone told me there was not a big market, not enough demand for such a system."

His first BK500 system, introduced in 2004 at the Leipzig World Prosthetic Exhibition, is rated up to 500 pounds; the kit, including pylon and components, cost him an estimated $12,000 and about nine months of work to design, manufacture, test, and transport. The cost of testing the system at Berlin University was $8,500, plus the cost of two BK500 systems that were discarded after testing.

The system initially reported sales of six to seven systems per month; 15 years later, sales average only one or two systems per month.

The AK500 system with polycentric knee with manual lock, rated to 500 pounds, presented even greater challenges, including a distributor deadline and the search for a 34mm carbon tube and knee that met his requirements. The kit, complete with pylons and components, cost more than $42,000 and four months to design, create, and test.

Initial sales of the AK500 averaged one or two systems per month for the first four years following its 2011 introduction; today, TiMed sells between five and seven systems per month.

While Radzinsky has ideas to improve and add new design features to both systems, until sales revenues increase, funds are currently insufficient to accomplish this, he admits.

He points out that other challenges for manufacturers lie in the L-Code process: since the density and pricing for the commonly used materials (aluminum, stainless steel, titanium, and carbon) vary greatly—some costing between $2 and $4 per pound, while others cost $20 to $22 per pound—he believes that L-Code reimbursements should vary commensurately.

"Titanium is not only more costly to purchase," says Radzinsky, "but more difficult to machine, with costlier cutting tools that need frequent replacement…." This point was also mentioned by clinicians, who must use extra manpower and replacement blades to customize titanium pylon length.

He suggests that the O&P community request increased reimbursement—perhaps at double the reimbursement for some other systems—with an L-Code assigned specifically to titanium systems.

"Using aluminum parts and materials under the existing L-Code may mean higher profits for prosthetists, compared to potentially losing reimbursement money by choosing titanium systems," Radzinsky says, "but testing of aluminum parts as currently designed for higher-weight patients has not proved that they are able to adapt or withstand the higher loading, impact, and torque," he worries.

"Those heavy-duty components cost a lot of money because there's a lot of engineering in them and the sales are small," Snell confirms. "So there's not any true extra reimbursement for the prosthetic facility, either. There are heavy-duty codes, but those codes are largely for active people, not obese people."

"The question that remains, then," says Hall, "is do manufacturers continue to increase the weight limit, because we've seen that, over time, some of the knees specifically are starting to be rated a little bit higher for weight? Or is it going to remain that there's just these niche manufacturers that are really unable to take on that small growing population?"

Another challenge related to availability is that functional K-level limitations and coding put many components beyond reach. Often the appropriate item is available—but only coded for a K3- or K4-level patient, while most candidates over 350 pounds are identified as K2.

"If you're dealing with an above-knee amputation, it truly is a problem getting a knee joint component for a 500-pound person," Snell explains. "Some of the components that would support a 500-pound person may be a function level so high that the patients are unable to qualify for it."

Lawall agrees: "If a patient is a K3, it opens the door for a lot of different equipment that can handle more weight. But when you're clinically obese, you typically fall into a K2 activity level, and there are limitations on the components we can choose. We can't use the K3 parts unless the patient wants to pay for it."

"There are plenty of feet available for obese or bariatric patients K3 and above," Schwelke says, "because companies such as Freedom Innovations or Össur will custom make feet based on the patient's weight and activity level. But when you get down to the K2 level, there's very little out there that you can use that's weight appropriate, that's made for overweight patients.

"If you have a K2 patient who's over 400 pounds, you need to get a foot. There are only two feet out there that I found—and because it's included in the base code for the prosthesis, there's no separate coding for a SACH foot. So we may have to spend almost $1,000 on a SACH foot that's rated for up to 500 pounds, but we're not going to be able to get paid for it."

Socket Fit and Weight Fluctuations
Jennifer Dowell, CPO, clinical support prosthetist, WillowWood, reports that calls asking specifically for feet and general endoskeletal componentry for heavier patients have increased. So have the requests she receives for advice, input, and troubleshooting problems that other clinicians encounter while fitting larger patients—especially those patients who have undergone bariatric surgery, with its promise of rapid and dramatic weight loss.

The necessary socket changes to maintain appropriate fit to match the limb's evolving shape and size aren't always possible, Dowell points out, whether due to reimbursement limitations or the inability to make new sockets fast enough to keep pace with the limb changes.

Effective use of the right liners can help to keep the patient safe and mobile, she notes. "Varying the gel profile, whether in overall thickness or in the contouring, could help keep a patient in a socket longer and more comfortably—and extend the time period between socket replacements. Even a three-millimeter change can make a big difference."

Schwelke describes a 340-pound, 6 foot 3 inch patient whose experience with bariatric surgery reduced his weight to 245 pounds. The total surface-bearing sockets Schwelke prefers allow very little room for any volume changes, and aren't made to be worn with socks that can be added or removed as daily volume fluctuates.

"But if you can comprehensively document a 100-pound difference within eight to ten months, addressing comorbidities and the surgical procedure, the need should be clearly evidenced for a whole new socket, new components because of the weight difference, and a new functional category; that's a justifiable change."

Dowell agrees, and notes that the value of CAD/CAM systems are often overlooked in these cases. "CAD in our industry really needs to be looked at as documentation—as a method of tracking the volume and weight loss changes during each visit."

Lawall notes that even without bariatric surgery, heavier patients tend to fluctuate more than other people. "To fit obese patients with a lot of fluctuation, sometimes you can put two flexible inner sockets in the leg. The principle is similar to the mobile inlays used in diabetic shoes for patients with edema: when their swelling is down, the insoles can be used to tighten up the looser fit. If the prosthetist makes a leg with two flexible sockets, the patient can also pull one out—or both—when volume increases."

He also suggests using an adjustable Click Medical RevoFit2 system, with a dial adjustment that allows the wearer to add or subtract millimeters of compression to their multi-panel socket as their volume fluctuates.

Tissue Issues
"At the transtibial level," Hall says, "obese patients tend to shrink more than average and move out of the socket more quickly, so new sockets are needed more quickly. Transfemoral amputees seem to develop more redundant tissue; in which case containing the tissue becomes a challenge. The conversation about adductor rolls (created when retracting muscles allow tissue to spill over the top of the socket in a roll) comes up quite a bit."

Carroll suggests that this condition, which can be painful, can be alleviated if the prosthetist designs the proximal aspect of the socket with a rounded radius rather than an edge, so the tissue rolls over a blunt surface.

Another alternative is to build the rim higher using foam materials, containing the tissue rolls and preventing a sore from forming where they might otherwise spill over the edge.

Dowell points again to the versatility of liners and the surprisingly innovative ways they can be adapted to solve fit and tissue management problems. Different fabrics to better stabilize soft tissue, care to avoid cutting liners short (which allows them to roll down the leg), and building reinforcements into the gel to maintain the liner's position during comfortable suspension are just a few of the problem-solving applications she suggests.

"People often approach me after a presentation and say, ‘I've been using your liners forever—I never thought of using one in that capacity,'" Dowell says.

Lawall notes that custom liners can also help tighten redundant tissue, controlling and containing it like a corset.

"Where you have a lot of heavy, dense, spongy, rotating tissue,"Schwelke warns, "you may have to do two or three diagnostic sockets to get the fit that will work for the patient. Pushing through inches of adipose tissue to transfer forces to the skeleton is tough."

"This is tissue that wasn't made to bear weight—and heavier amputee patients are putting up to 50 percent and even 100 percent more weight on it when it's compressed in a socket. There are bound to be challenges," Snell says.

Bariatric Patients Face Their Own Challenges

Like any other prosthetic patient, an individual with weight issues deserves respect, courtesy, kindness, and the best quality of life we can help them achieve, Carroll reminds us.

"There's always risk. Just because they might break something doesn't mean that we should leave them in a wheelchair. Keep an open mind. There's great hope for heavier individuals, and if it only helps one person get out of a hospital and walking again, it's worth our effort."

Trying something new and different is part of the normal process, Hall believes, and to avoid disappointment, "patients should be made aware that things might not work quite as we anticipated because of their size."

Almost unanimously, respondents stressed the importance of physical therapy for this patient population.

"Even down the road, amputees should continue exercising," Lawall advises, "not so much to lose the weight but to try to strengthen the muscles. At any age you can double your strength, and strength is particularly important for obese patients in the long term. Two or three years after being fit with their prosthesis, they need to continue creating and working on the right muscles to give them stability. Patients can ask their doctor if they can go back and see a physical therapist three or four years later."

"Working with physical therapists is really key," Hall agrees. "The whole medical team is important when helping our challenging patients; but with my obese patients, the physical therapist will pick up on things that I hadn't realized…. One of the things we do really well as a profession is get patients into physical therapy initially after an amputation, but I don't think we're as good about getting them back into physical therapy a few years out. That might be one way to address some of our ongoing concerns regarding knee and hip flexion contractures."

Lawall notes that the right support team includes a good physical medicine and rehabilitation physician and a PT who specializes in prosthetics and has many years of experience with prosthetic patients. Some therapists, he cautions, may only see one prosthetic patient a year.

"It's all about making sure that we encourage the use of the prosthesis every day, and putting it on first thing in the morning," says Carroll. "It's important to work with therapists, and to recruit and educate family members as helpers to achieve that goal—and if the individual is institutionalized, to encourage the people at the nursing home to get the person out of bed and make sure that they get the prosthesis on—both to maintain their level of mobility, and to improve their quality of life."

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.

*BMI = (Body weight in kilograms) / (Height in meters)2; or BMI = (Body weight in pounds) x 703 / (Height in inches) x (Height in inches)