There has been mounting pressure in recent years from third-party payers—and consumers—for evidence that a device or procedure actually performs as claimed before considering payment for services. In fact, Section 6301 of the Patient Protection and Affordable Care Act authorized the establishment of the Patient- Centered Outcomes Research Institute for the express purpose of examining the comparative clinical effectiveness of medical treatments, procedures, drugs, and medical devices, which may impact both government and private insurer's coverage determinations.
While there have been great technological advances in the fields of orthotics, prosthetics, and pedorthics, there is relatively little pedorthics-oriented scientific research to quantify the effectiveness of these modalities. Ask any pedorthist and he or she will be happy to provide a heap of anecdotal evidence that foot orthotics and shoe modifications work. But is there published scientific data to prove it?
A review of the literature reveals that a great many of the published research studies on the efficacy of foot orthotics to treat specific problems amount to vague patient surveys that are not at all specific about what types of orthotics were used.
Hawke et al. compiled and analyzed a Cochrane Database Systematic Review titled "Custom-Made Foot Orthoses for the Treatment of Foot Pain," in 2008.1 They looked at 11 trials that involved more than 1,300 participants and concluded that custom-made foot orthotics were effective for painful pes cavus, rearfoot pain resulting from rheumatoid arthritis (RA), juvenile idiopathic arthritis (JIA)-related foot pain, and painful hallux valgus; however, non-custom foot orthotics appeared just as effective for JIA. It is unclear if custom-made foot orthotics were effective for plantar fasciitis or RA-related metatarsophalangeal joint pain. They went on to say that there is limited evidence on which to base clinical decisions regarding the prescription of custom-made foot orthotics for the treatment of foot pain. Currently, there is gold-level evidence, defined as a double-blind study with at least 50 participants per group, concealment of treatment allocation, and at least an 80 percent follow-up rate, for painful pes cavus. Additionally, there is silver-level evidence, which would include evidence from at least one study of non-randomized cohorts and/or evidence from at least one case-control study, for foot pain in patients with JIA, RA, plantar fasciitis, and hallux valgus. But they also said that custom-made foot orthotics were at least a safe intervention in all studies.
The waters are even muddier when one reviews what the research has to say about which foot orthotic molding technique is superior. Several researchers have tried to answer this question. In 2006, Guldemond et al. found that there were no perceived differences in the finished orthoses regardless of whether a full-weight bearing foam impression, a semi-weight bearing (SWB) foam impression, or an accommodative plaster suspension mold was used to fabricate the orthotics.2 Laughton et al., in 2002, compared four methods for molding: nonweight bearing (NWB) plaster, SWB foam, and both NWB and SWB three-dimensional scan.3 They found that the measures were significantly influenced by the method used and that the methods varied in reliability. In 2008, Trotter and Pierrynowski examined the ability of foot care professionals to cast feet using the NWB plaster and gait-referenced foam casting techniques.4 They concluded that intracaster reliability was excellent using both methods while intercaster reliability was poor and that "although plaster…casting is widely perceived…as the gold standard, other casting techniques may prove equally reliable."
Ki et al. compared plantar pressure distribution patterns between orthotics fabricated using the CAD-CAM and foam-impression methods in a study published in 2008 and concluded that both methods redistributed peak pressures.5 Peak pressures in the forefoot were slightly lower with the CAD-CAM orthotics, but otherwise patterns were essentially the same. Levac's literature review on the subject, published in 2010, concluded that the often conflicting and inconclusive findings of the various studies raise the question of the necessity of accurate casts in the first place.6 Another of Levac's conclusions—one that I agree with wholeheartedly—is that clinicians are responsible for researching the pros and cons of different casting methods.6
A 2012 study by Brodsky et al. explored the effects of heating on the mechanical properties of insole materials.7 They found, as I expected, that heat does indeed affect the mechanical properties of the materials used to fabricate foot orthotics. The materials tested (#1 and #2 PLASTAZOTE®, Puff®, and NickelPlast™) became stiffer and less effective in the attenuation of applied forces. While I do not think this study sheds much light on the subject for pedorthists who have extensive experience fabricating their own orthotics, it does raise awareness for those new to the profession, or for those who do not fabricate their own orthotics. The swatch of sample material one picks up from a booth at a tradeshow has necessarily different properties once it is heated and formed into a foot orthotic. One follow-up question that came to mind after reading this study is whether manufacturers should test and list the Shore A durometer of a material after heating and vacuum forming it instead of before, as is the current standard. It would seem to be a lot more practical to the clinician.
In regards to shoe modifications, there has been very little research done at all. Brown et al. looked at the efficacy of rocker soles in reducing plantar pressures in a 2004 study.8 When comparing an unmodified shoe, a shoe with a forefoot-only rocker sole, a double rocker sole, and a negative heel rocker sole, they found significant reduction of peak pressures under the forefoot using all three types of rocker soles. This study lends scientific credence to the prescription of rocker soles for patients who need forefoot pressure reduction, such as those who have diabetes-related neuropathy and ulceration.
Fortunately, there has been more pedorthic research presented and published recently than in years past, and the future is bright. In 2011, the Pedorthic Foundation donated $5,000 to support the National Foot Biomechanics Research Center (NFBRC) Initiative. The NFBRC Initiative, which is based out of the Georgia Institute of Technology College of Sciences, School of Applied Physiology, Atlanta, has already completed and presented the findings of its first two research projects. The first was a study of plantar foot tissue properties and the second a study on the kinematics of late stance forefoot rocker rollover. Both research studies achieved their objectives, and the group is a step closer to the next stage, which is a more complete study.
The first of the NFBRC Initiative's studies, "The Use of Ultrasound to Assess Plantar Tissue and Stiffness Properties in the Midfoot," was designed because while foot orthotics are a common and often effective intervention for various foot disorders, it is not understood well how plantar soft tissues and skeletal structures interface with the orthotics. The study concludes that plantar midfoot tissue stiffness values vary notably between weight bearing and NWB, and foot orthotics appear to have the ability to alter the stiffness properties of the plantar soft tissues.
There has been significant research done regarding the orthotic and pedorthic care of the diabetic foot. Unfortunately, not all of it is favorable. I expect this is an area where research will continue, but we need more and new pedorthic research on other topics as well. While there has been some groundbreaking research performed, additional studies need to be designed to further understand the effects of shear on skin breakdown and what can be done to reduce it. We absolutely need double-blind studies to prove the efficacy of custom foot orthotics in the treatment of any number of different foot conditions. With the effective overhaul of the U.S. healthcare system, outcome-based research will become more important than ever if we hope to justify our existence and continue to get paid for the services and products we provide. Empirical data is necessary for pedorthics to thrive going forward.
Dennis Janisse, CPed, is president and CEO of National Pedorthic Services, headquartered in Milwaukee, Wisconsin. He also is a clinical assistant professor in the Department of Physical Medicine and Rehabilitation at the Medical College of Wisconsin, Milwaukee, adjunct professor at the University of Pittsburgh, Pennsylvania, and director of scientific affairs for Orthofeet, Northvale, New Jersey.
Resources
- Hawke, F., J. Burns, J. A. Radford, and V. Du Toit. 2008. Custom-made foot orthoses for the treatment of foot pain. Cochrane Database of Systematic Reviews 16(3).
- Guldemond, N. A., P. Leffers, A. P. Sanders, H. Emmen, N. C. Schaper, and G. H. Walenkamp. 2006. Casting methods and plantar pressure: Effects of custom-made foot orthoses on dynamic plantar pressure distribution. Journal of the American Podiatric Medical Association 96(1): 9–18.
- Laughton, C., I. McClay Davis, and D. S. Williams. 2002. A comparison of four methods of obtaining a negative impression of the foot. Journal of the American Podiatric Medical Association 92(5): 261–8.
- Trotter, L. C., and M. R. Pierrynowski. 2008. Ability of foot care professionals to cast feet using the non-weight bearing plaster and the gait-referenced foam casting techniques. Journal of the American Podiatric Medical Association 98(1): 14–8.
- Ki, S. W., A. K. L. Leung, and A. N. M. Li. 2008. Comparison of plantar pressure distribution patterns between foot orthoses provided by the CAD-CAM and foam impression methods. Prosthetics and Orthotics International 32(3): 356–62.
- Levac, K. Casting techniques: A review of the literature. Kal Orthoses. kalorthoses.ca/casting-techniques-a-review-of-the-literature
- Brodsky, J. W., J. Brajtbord, S. C. Coleman, S. Raut, and F. E. Polo. 2012. Effect of heating on the mechanical properties of insole materials. Foot & Ankle International 33(9): 772–8.
- Brown, D., J. J. Wertsch, G. F. Harris, J. Klein, and D. Janisse. 2004. Effect of rocker soles on plantar pressures. Archives of Physical Medicine and Rehabilitation 85(1):81–6.
