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.