Authors: Orthoses Study Is 'Most Rigorous Of Its Kind'

    We read with interest an article recently published in Podiatry Today, “Are Orthoses Effective Against Plantar Fasciitis In The Long Run?” (see page 8, September 2006). As the study investigators referred to in this article, we cannot let the opportunity pass to clear up some misconceptions presented in this article.1 In particular, we want to correct certain statements made by Russell Volpe, DPM, and Ronald Valmassy, DPM, regarding the research undertaken in our study.     In the article, Dr. Volpe suggests that, “The fact that orthotic devices alone are not enough is a ‘serious flaw’ in the study.” Unfortunately, statements such as this demonstrate a fundamental misunderstanding of the very nature of the findings from a randomized controlled trial. If investigators want to make definitive conclusions regarding an intervention, then ideally each group in a randomized trial will vary by only one variable. In the case of our trial, the one variable that was different between groups was the type of orthosis.     By doing so, we were able to conclude with confidence that any difference between the groups was due only to the orthoses. If we provided one group with other secondary interventions — “other treatments” as Dr. Volpe suggests — we would not have been able to determine which intervention caused the effect if one were found. This element is essential to the execution and interpretation of randomized controlled trials if investigators want to be definitive in their conclusions.     Incidentally, although it has no impact on the conclusions of our trial, we did not, as Dr. Volpe suggests, just treat participants in our study with foot orthoses alone. All participants were encouraged not to use any other interventions during the trial in an attempt to avoid one group acting differently to another group once the orthotic intervention began. However, all participants initially received low-Dye taping prior to receiving orthoses, were advised to carry out calf muscle stretches and were also provided with education regarding plantar fasciitis and appropriate footwear.     As stated previously, by treating each group exactly the same, with the exception of the type of orthosis received, we could make definitive conclusions about the effectiveness of the orthoses relative to each other. In addition, by including a sham group, we could, to some extent, gain an understanding of the actual effect (compared to a sham treatment) of a foot orthosis for plantar fasciitis.     Furthermore, Dr. Volpe, in his statement “… that this is not how orthoses are used by most serious, respected foot professionals,” and Dr. Valmassy, in his assertion, “I might evaluate the customized device used in this study and feel that they are not only not true functional devices but possibly no better than over-the-counter devices,” attempt to undermine the findings of our study by trying to discredit our credentials in our prescription and use of foot orthoses. The description of each type of device was clearly stated in the article. The customized device was similar to that which is commonly prescribed by biomechanically minded podiatric physicians worldwide for a variety of feet and foot conditions (similar to that described by Hice).2 The rationale for the prescription of all devices used in our trial is again clearly stated in the methods and can be further appreciated by reading a previous research article we published prior to our randomized trial.3     To attempt to undermine our study’s findings by trying to throw doubt over our credentials and our ability to treat foot disorders is extreme and unfair. For the record, we are both podiatrists, we both have greater than 20 years experience with biomechanics and foot orthoses and each of us has 15 years experience teaching biomechanics and foot orthoses at both an undergraduate and postgraduate level. We have contributed significant research output in podiatry, musculoskeletal and medical journals; and we both initially “cut our teeth” on Root-style biomechanics. Dr. Landorf even complimented his undergraduate education relating to foot orthoses and biomechanics by attending postgraduate seminars at the California College of Podiatric Medicine.     To date, our trial published in the Archives of Internal Medicine is the most rigorous of its kind.1 Its findings should not simply be swept under the carpet by trying to discredit our ability to conduct such a trial. Like the podiatry profession at large, we too have had to grapple with the findings. They were not the findings we expected. However, they are the most precise estimate to date of the effectiveness of foot orthoses for the treatment of plantar fasciitis.     Finally, the results from our randomized trial are only half the story from our article. The second half includes a meta-analysis, in which results from other appropriate randomized trials that evaluated foot orthoses for the treatment of plantar fasciitis were combined. The overwhelming finding from this meta-analysis, the highest form of evidence, is that when treating plantar fasciitis with foot orthoses, there is no significant difference between customized and appropriate prefabricated (over-the-counter) foot orthoses, even over the long term. This no doubt emphasizes the natural course (one of resolution) of plantar fasciitis and undoubtedly highlights that appropriate prefabricated foot orthoses (like the ones used in our trial) should be used first if orthoses are deemed necessary.     Karl B. Landorf, PhD     Senior Lecturer and Research Coordinator     La Trobe University     Bundoora (Melbourne), Australia     Anne-Maree Keenan, MAppSc     Research Fellow     University of Leeds     Leeds, United Kingdom

Clarifying Concerns About The Orthoses Study

    Dr. Volpe responds:     I would like to take this opportunity to respond to some of the objections made by the authors in their letter to the editor responding to an article in the September 2006 Podiatry Today in which I was quoted.     I appreciate the authors taking pains to defend the integrity of a “randomized controlled trial.” However, the implication that I have a “fundamental misunderstanding” of the nature of a randomized controlled trial misses the point. I am well aware of the need to have each group in a randomized trial vary by only one variable. My comments, when read in their entirety, acknowledge that the addition of other treatments in a research study would compromise the ability to draw conclusions about the effect of individual treatments.     Perhaps the use of my phrase “serious flaw” was applied broadly to the research itself when my intention was to suggest that conclusions about the efficacy of custom foot orthoses as part of a comprehensive management plan are “flawed” when this randomized controlled trial reports on the effect of that one variable over the short- and long-term treatment period.     I agree that we need such randomized controlled trials to advance outcomes research in gaining more evidence about critical components of what we do. However, as a practitioner who must apply the results of research to patients, I stand by my opinion that while this study adds outcomes value on the subject, the conclusions must be applied cautiously when standard practice combines custom orthosis therapy concurrently with other modalities.     I understand that the intent of the study was to compare the effect of sham, prefabricated and custom and report on any differences, if any, between the random groups. My contention is that using orthoses in conjunction with other modalities, while not conducive to randomized controlled trials, is a reality of sound practice and may provide an important additional angle from which to view the reported study results.     Dr. Landorf continues by stating that patients in the study did receive other treatments outside of the trial period. As this was not mentioned in the article, a reader would have no way of knowing that these plantar fasciitis patients had any other interventions other than the trial orthoses assigned randomly. I would point out that the clinical application of the findings in this study is where my issue lies. In practice, adjunctive treatments are not “suspended” necessarily with dispensing of orthoses. I would suggest that the success of custom orthoses is based, in part, on maintenance of proper foot position while adjunctive treatment is ongoing.     Finally, I continue to have concerns, as did Dr. Valmassy, about the type of custom foot orthosis used in this randomized trial. Dr. Landorf defends “the customized device as similar to that which is commonly prescribed by biomechanically-minded podiatric physicians worldwide for a variety of feet and foot conditions (similar to that described by Hice).” In the clinical protocol section of the article, the authors state, “the shell was made from semi-rigid polypropylene and a firm foam heel post was applied inferior to the heel. All devices were made to look as similar as possible (i.e. in color and shape) given the materials used.”     The reality is that I use a wide variety of custom foot orthoses and orthosis modifications to treat my plantar fasciitis patients with biomechanical imbalances. I might add an extended forefoot post for the patient with a forefoot varus, a bilateral heel raise for an equinus influence and a unilateral lift for a limb length discrepancy. These will each be significantly different custom foot orthoses and would offer the patient a degree of mechanical control impossible to derive from the aforementioned uniform “study” custom foot orthosis described by the study authors. My carefully prescribed custom foot orthoses for biomechanically-induced plantar fasciitis do not “look as similar as possible.” In fact, what makes them truly custom, and better than prefabricated devices in many cases, is their very differences tailored to the needs of the individual patient.     I will pay more careful attention to the plantar fasciitis study that compares prefabricated foot orthoses to custom orthoses that are truly custom and individually prescribed for the specific biomechanical needs of the individual patient. Researchers need to recognize that although variability is added when all the devices in one study group — in this case, the custom devices — are individualized, we would finally have a study that acknowledges the unique and essential differences in truly custom foot orthoses and compares those, not standard custom devices “made to look as similar as possible,” to the prefabricated alternative.     Russell G. Volpe, DPM     Diplomate, American Board of Podiatric Orthopedics and Primary Podiatric Medicine     Professor and Chair     Departments of Orthopedics and Pediatrics     New York College of Podiatric Medicine     Foot Clinics of New York
 

 

References:

1. Landorf KB, Keenan A-M, Herbert RD. Effectiveness of Foot Orthoses to Treat Plantar Fasciitis: A Randomized Trial. Archives Internal Med. 2006;166(12):1305-1310.
2. Hice GA. Orthotic treatment of feet having a high oblique midtarsal joint axis. J Am Pod Assoc. 1984;74(11):577-582.
3. Landorf K, Keenan A-M, Rushworth RL. Foot Orthosis Prescription Habits of Australian and New Zealand Podiatric Physicians. J Am Pod Med Assoc. 2001;91(4):174-183.

 

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