May 2011

Prefab-custom orthoses debate mellows with age

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Not so long ago, the effectiveness of prefabricated foot orthoses relative to their custom brethren was a bitterly divisive topic. But the vitriol has dissipated over time, as practitioners have turned their focus to the appropriate selective use of each type of device.

by Cary Groner

A dozen years ago, when research first suggested that prefabricated in-shoe foot orthoses were as effective as their more expensive custom brethren for treating plantar fasciitis, the podiatric community responded with consternation.1 The study was viewed as a threat, not only against conventional wisdom but also against a lucrative source of revenue.

As evidence has accumulated, however, and as clinicians debate the means by which orthoses of any stripe actually work, ongoing discussion of the relative merits of prefabricated vs custom foot orthoses has become more muted (see “In search of a mechanism for foot orthoses’ effects,”). A consensus is emerging, in fact, as to the conditions for which prefabricated orthoses are best suited, and those for which practitioners will get better outcomes with custom inserts.

“There’s definitely a place for off-the-shelf arch support,” said Michael Gross, PT, PhD, a professor of physical therapy at the University of North Carolina. “When the patient just needs a little help, and we can save them money, I’ll suggest that. But if the condition is more serious, and I think they’re just going to be wasting time, I like to fit them with a custom device.”

Clinicians have loosely defined which conditions fall into which category—though as consensus goes, this is a contentious one, and in some cases they still disagree.

“For plantar fasciitis, functional hallux limitus, and pediatric flatfoot, I think you can get positive clinical outcomes with prefabricated orthoses,” said Paul Scherer, DPM, MS, clinical professor in the School of Podiatric Medicine at the Western University of Health Sciences in Pomona, CA, and CEO of ProLab Orthotics in Napa, CA, which makes both prefabricated and custom orthoses.

“There are problems you can’t treat successfully that way, though,” he continued. “No prefabricated orthotic is designed to control the abnormal shape and function of a cavus foot. They won’t work for tarsal coalition, either, because of the abnormal foot shape. Prefabricated orthotics usually have a shallow heel cup and lack a rearfoot post, so they don’t control rearfoot motion; as a result, I don’t think they’re effective for tarsal tunnel syndrome. And because they’re not designed to control muscle power or function, they won’t work on posterior tibial dysfunction.”

The research

Studies comparing prefab and custom orthoses have become more common in the last decade, but definitive conclusions about the relative benefits of each remain elusive. In a Cochrane review from 2008, Australian researchers reported that custom devices were effective than sham orthoses for painful pes cavus and rearfoot pain in rheumatoid arthritis, more effective than supportive shoes but not prefabricated neoprene inserts for foot pain in juvenile idiopathic arthritis, and more effective than no treatment for painful hallux valgus. The researchers concluded, however, that there was limited evidence on which to base clinical decisions when it came to foot pain generally.2

In a 2009 study, British researchers found no significant difference in effect on plantar pressures between contoured prefab orthoses and customized orthoses.3 Research published in the Journal of the American Podiatric Medical Association (JAPMA) that same year reported that prefab orthoses significantly relieved pain associated with hallux valgus, as well as arch, knee, and back pain.4

Prefab devices have received consistently good reviews in the literature when it comes to comfort and injury prevention. For example, in a 2004 study of 874 Israeli infantry recruits, researchers dispensed four types of orthoses: soft prefab, soft custom, semirigid biomechanical, and semirigid prefab. By the end of basic training, there was no significant difference among the groups in the incidence of stress fractures, ankle sprains, or foot problems, which led to the conclusion that given the lower cost, prefab devices were preferable. It’s worth noting, however, that there were important discrepancies in the number of recruits who completed training in the soft prefab orthoses (53%) versus the other types (72% for soft custom, 75% for semirigid biomechanical, and 82% for semirigid prefab).5

Another meta-analysis published in the March 2007 issue of Foot & Ankle International, moreover, found no difference between custom and prefab devices in preventing lower limb overuse conditions.6

Even in conditions for which many clinicians prefer to prescribe custom orthoses, some research suggests that off-the-shelf ones may work nearly as well under the right conditions. For example, in a paper published in Clinical Rehabilitation in 2009, South Korean researchers reported that in 42 patients with rheumatoid foot lesions, both prefabricated and custom orthoses reduced foot pain equivalently when paired with special forefoot-rockered shoes.7 And in a 2008 study conducted in New York, 37 subjects with either excessively high or low arches were tested to see whether semi-custom devices gave rearfoot control similar to that provided by custom ones. Eversion excursion was reduced with both devices, but for eversion velocity, the custom device produced better results.8

Chronology and pathology

“It’s analogous to how you’d make a decision about custom versus off-the-rack clothes,” said Glen Pfeffer, director of the Foot and Ankle Center at Cedars Sinai Medical Center in Los Angeles—and lead author of the 1999 study that touched off the initial controversy. “The custom may be nicer and fit better, but it’s way more expensive. We’ve made huge advances in the past decade with prefabricated orthotics; there are now myriad shapes and space-age materials available.”

For Pfeffer, the most common and basic condition that can be addressed with prefabricated orthoses is stress on the feet, particularly in overweight patients. He’s similarly sanguine about treating plantar fasciitis with something off the shelf. However, he considers custom devices when patients present with diabetes, particularly with significant concomitant neuropathy. He also prefers custom orthoses when addressing posterior tibial tendinopathy and a resulting collapsed arch.

In many cases, the question becomes one of chronology as much as pathology, however.

“We’re talking about initial treatment with prefabricated devices,” Pfeffer said. “If someone comes back to me after two months and they still have heel pain, or a bothersome callus, or trouble with their Achilles tendon, then we’ll get them a custom orthotic. There’s a huge role for that when people have failed more conservative care.”

Pfeffer’s decision algorithm begins with proper diagnosis.

“Someone may be flatfooted because of a tendon rupture,” he said. “Or maybe their pain is from a stress fracture. My first decision is, how can I treat this as benignly and cost-effectively as possible, without being invasive to either the body or the pocketbook? The next decision is how long I’ll let it go without something more invasive. I’ll say to the patient, ‘Let’s give it six or eight weeks. I don’t want to do surgery right now. Let’s hold off on having an injection, or an expensive custom orthotic.’ But then, after eight weeks, all bets are off; you have to bring out the bigger guns. The key for any of these problems is not to let it go on too long.”

Severity drives decisions

Daniel Hasso, CPO, director of orthotics for Scheck and Siress in Oakbrook Terrace, IL, also considers it important to distinguish between diabetic and nondiabetic patients, and agrees that the severity of the disease, and any associated neuropathy, affect decisions about orthosis type.

“If there’s no history and less risk of ulceration, and we just want to maintain and protect, I think the prefabricated devices are extremely affordable, functional, and protective,” he said. “But if a diabetes patient has a foot deformity or a history of ulceration—and based on how you feel the load is distributed through that foot—then custom is the way to go.”

In nondiabetic patients, Hasso considers the presentation. In someone with plantar fasciitis in a relatively normal looking foot, for example, he’s comfortable offering an off-the-shelf device. More serious foot pathology is another matter.

“If someone has a lot of pronation, calcaneal valgus of, say, ten degrees, a navicular that’s almost on the floor, and a deviated forefoot, the prefab world isn’t designed for that,” he explained. “You’ve got to get your hands on, see how well you can realign the foot, and hopefully design a device that will help.”

Michael Gross agrees that the severity of pathology drives such decisions.

“For someone without a special-needs foot, who just needs a little support for the arch to decrease the tensile stress on the plantar fascia, something over-the-counter will work,” he said. “For someone with a very cavus foot, it’s hard to find something prefab that will fill in that arch space sufficiently. If somebody has a pronounced forefoot varus that is driving the collapse of their foot, the bump in the arch space you get from a prefabricated device won’t provide the necessary posting.”

Gross was the lead author of a 2002 paper reporting that semirigid custom orthoses significantly reduced pain and disability for patients with chronic (average of 21.3 months) plantar fasciitis, which is a good example of how clinicians make decisions based on the patient’s response to initial interventions.9

“We weren’t studying people who did well with off-the-shelf devices,” Gross said. “The people included in the study still had the problem after earlier measures failed.”

Gross also pointed out that the purported cost-effectiveness of prefabricated orthoses is often canceled out by the sheer volume of insoles purchased in a futile attempt to find something that works.

“I have patients who have spent hundreds of dollars and tried a gazillion things, and it hasn’t worked,” he said. “Then we make them a custom device and they do quite well.”

Like so many of his colleagues, Gross emphasized that a successful therapeutic approach begins with an accurate assessment of the pathological and biomechanical problems the patient is experiencing.

“What’s driving the collapse of the foot?” he asked. “Is it a huge forefoot varus? Is it a tight triceps surae? Or does somebody have extreme genu varus, or tibial varum, or both? Because those could make the distal third of the leg approach the foot well off from vertical and drive pronation. If I have patients with those issues, I doubt that a non-custom arch support is going to solve their problems.”

From prefab to rehab

Thomas McPoil, PT, PhD, a professor in the School of Physical Therapy at Regis University in Denver, isn’t convinced that custom devices offer superior control than prefabricated ones for most conditions.

“I haven’t seen data yet that convinces me that there’s going to be any better motion control with a custom orthosis,” he said. “If a person has patellofemoral pain, anterior knee pain, posterior tibial tendinitis, medial tibial stress syndrome, or fasciitis, I think prefab is good enough. I do think that in individuals with forefoot pain, you have to do some kind of customization. That’s also true for those with very high arches or rheumatoid arthritis.”

When patients primarily need pressure relief, McPoil blurs the line between off-the-shelf and custom by assembling an orthosis from prefabricated components and top covers.

He is also critical of the quality of some studies used to justify custom devices. For example, two recent papers purported to find custom devices superior for lower-extremity musculoskeletal pain and gait economy.10,11 The primary weakness, McPoil explained, is that the authors compared full-contact custom devices with flat, prefab insoles made of low-density open-cell foam. The papers also acknowledged that the lead author receives a salary as a technical consultant from the company that supplied the custom orthoses.

The papers’ lead author, Leslie Trotter, DC, CPed, who is associated with the Foot-Knee-Back Clinic at McMaster University in Ontario, Canada, replied to LER via email that the study design was approved by the university’s ethics board and JAPMA’s peer-review process. She also noted that the papers identify the rationale for the use of the devices chosen. (The articles note that there is wide variety in prefabricated devices, and that those used were representative of products that are readily available.)

Trotter also described the clinical trial process as “humbling,” and wrote, “It has nudged me from feeling like I knew my subject area very well to one where I realize how little I actually do know with certainty.”

McPoil admits that professionals remain somewhat perplexed by how, exactly, orthoses work, which contributes to the difficulty of deciding what to use.

“I believe that when you give someone an orthotic, its effect is multifactorial,” he said. “When my patient feels better, that could be due to factors that are biomechanical, neurosensory, or that have to do with shock attenuation. The problem I have as a clinician is that in any given patient I may not know which factor is predominant.”

McPoil also believes, as many practitioners do, that patients—and particularly athletes—should strengthen their feet so they don’t need orthotic support forever.

“Once the pain subsides, I want them to wean themselves from the device so they’re using it only when they are out doing the provoking activity,” he said. “You have to consider the eventual effect of these on intrinsic muscle strength, and I worry about doing something that allows the foot to just sit there and rest.”

Too much static?

Many clinicians now believe that static plantar pressure values, such as those measured by at least one of the semi-customization kiosks increasingly seen in drugstores, are of limited utility in choosing or modifying orthoses.

A paper McPoil published in JAPMA in 2006 found that such data could be used to predict only 27% of the height of the medial longitudinal arch, for example.12

“If I’m dealing with a patient who has insensitive feet, I want pressure data so I can determine the areas of high pressure and design the orthotic with relief areas to accommodate that,” he told LER. “But in a patient with fasciitis, what’s the pressure data telling you? It might give you half the information you need to build an orthotic.”

Paul Scherer agreed.

“A pressure-sensitive mat isn’t going to tell you the contour of the foot or the height of the arch,” he said. “If I gave you a map of a city block in San Francisco and told you the exact dimensions and weight of every building on that block, could you tell me what the skyline looked like? No! What about the Transamerica pyramid? What about Coit Tower? Just because you can produce a pretty picture doesn’t mean you can make decisions about the contour of the foot.”

According to Michael Gross, at best such systems produce an illusion of therapeutic benefit.

“If your patient stands in an uncontrolled fashion on a pressure sensor, and pronates excessively, the system will capture an impression of the foot in a deformed state,” he pointed out. “If you use that data to build a device, you’ll build something with too low of an arch, and it won’t be supportive enough. But even if you realize that and try to compensate, you still don’t know what the architecture of the device should be, because the system can’t determine what issues are driving the collapse of the foot.”

Dynamic pressure measuring systems are another matter. Many clinicians find them useful in designing and adjusting custom orthoses for diabetes patients, athletes, and others, as reported recently in LER (see “Pressure Treatment: Dynamic data guide orthotic therapy.”)

Adaptation and evolution

As noted earlier, McPoil sometimes pursues a hybrid approach by modifying one or more off-the-shelf devices. Daniel Hasso agrees that this strategy can be useful.

“You have to consider the material that the prefab device is made of,” he said. “Does it lend itself to the glues and materials that we have in our office to make adjustments? I can work with many materials, though not with silicone. But if I have a prefabricated device that is ninety percent there, and I just need to raise the metatarsal or add some posting, it’s easy for me to make those changes.”

The clinical community is more willing to consider prefabricated devices not only because they’re modifiable but also because they’ve become better. Part of this has to do with trickle-down from improving custom designs.

“In the 1960s and 1970s we began to realize that what made feet different in different people wasn’t just their shape, but their mechanics, and that changed the face of custom orthotics,” Paul Scherer said. “People making prefabricated devices looked at the changes in the custom ones and realized there was a big difference between them, so in the 1980s they started modifying the prefabs to incorporate more mechanical concepts.”

The off-the-shelf devices available now represent a new generation and are significantly more advanced than their predecessors. One model, for example, includes a skive—a particular rearfoot shape based on the axis of the subtalar joint that was previously available only in custom devices. Others offer much deeper heel cups than earlier models did, which not only helps control rearfoot motion but also allows for the incorporation of more cushioning, if necessary.

“Today the prefabricated orthotic industry is evolving by borrowing the modifications learned by those who made custom devices,” Scherer said. “They’ve learned that a more rigid device is more effective, that a lighter device is more effective. Podiatrists and orthotists have a daily quandary, deciding whether to use a prefabricated or a custom device. The more we learn about the foot, the better both of those options are going to be.”

Cary Groner is a freelance writer based in the San Francisco Bay Area.

References

1. Pfeffer G, Bacchetti P, Deland J, et al. Comparison of custom and prefabricated orthoses in the initial treatment of proximal plantar fasciitis. Foot Ankle Int 1999;20(4):214-221.

2. Hawke F, Burns J, Radford JA, du Toit V. Custom-made foot orthoses for the treatment of foot pain. Cochrane Database Syst Rev 2008;16(3):CD006801.

3. Redmond AC, Landorf KB, Keenan AM. Contoured, prefabricated foot orthoses demonstrate comparable mechanical properties to contoured, customized foot orthoses: a plantar pressure study. J Foot Ankle Res 2009;2:20.

4. Landsman A, Defronzo D, Andreson J, Roukis T. Scientific assessment of over-the-counter foot orthoses to determine their effects on pain, balance, and foot deformities. J Am Podiatr Med Assoc 2009;99(3):206-215.

5. Finestone A, Novack V, Farfel A, et al. A prospective study of the effect of foot orthoses composition and fabrication on comfort and the incidence of overuse injuries. Foot Ankle Int 2004;25(7):462-466.

6. Collins N, Bisset L, McPoil T, Vicenzino B. Foot orthoses in lower limb overuse conditions: a systematic review and meta-analysis. Foot Ankle Int 2007;28(3):396-412.

7. Cho NS, Hwang JH, Chang HJ, et al. Randomized controlled trial for clinical effects of varying types of insoles combined with specialized shoes in patients with rheumatoid arthritis of the foot. Clin Rehabil 2009;23(6):512-521.

8.  Zifchock RA, Davis I. A comparison of semi-custom and custom foot orthotic devices in high and low arched individuals during walking. Clin Biomech 2008;23(10):1287-1293.

9. Gross MT, Byers JM, Krafft JL, et al. The impact of custom semirigid foot orthotics on pain and disability for individuals with plantar fasciitis. J Orthop Sports Phys Ther 2002;32(4):149-157.

10. Trotter LC, Pierrynowski MR. The short-term effectiveness of full contact custom-made foot orthoses and prefabricated shoe inserts on lower extremity musculoskeletal pain: a randomized clinical trial. J Am Podiatr Med Assoc 2008;98(5):357-363.

11. Trotter LC, Pierrynowski MR. Changes in gait economy between full contact custom-made foot orthoses and prefabricated inserts in patients with musculoskeletal pain: a randomized clinical trial. J Am Podiatr Med Assoc 2008;98(6):429-435.

12. McPoil TG, Cornwall MW. Use of plantar contact area to predict medial longitudinal arch height during walking. J Am Podiatr Med Assoc 2006;96(6):489-494.

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