This author explores the prevalence of arch support intolerance and discusses implications for patient assessment and treatment.
Any physician with experience prescribing arch supports is aware that some patients cannot tolerate such devices. This intolerance constitutes a clinical symptom.
The importance of this symptom may be largely unknown in medicine. This may be because 1) the literature rarely reports arch support intolerance in connection with clinical entities 2) physicians are not in agreement as to arch support intolerance prevalence and 3) even if the prevalence of arch support intolerance were known, its etiology would be the subject of much speculation.
My research study suggests that arch support intolerance is widespread. It is not within the scope of this article to define all the possible etiologies of arch support intolerance. However, the readers may gain some insight into arch support intolerance with a focused literature review of articles covering the topics of tarsal coalition, peroneal spastic flatfoot and sinus tarsi syndrome.
I recorded the extent of the diverse podiatric physician opinions on the topic of arch support intolerance at the 2007 American Podiatric Medical Association (APMA) House of Delegates meeting and the 2016 APMA House of Delegates (HOD) meeting. The delegates from the House of Delegates meetings voluntarily responded to a non-scientific survey regarding what percentage of the population do not tolerate arch supports. There had been no previous study regarding arch support intolerance or orthotic intolerance published prior to either the 2007 or 2016 survey.
The surveys (see photos 1 and 2) demonstrate that podiatric physicians are not in agreement regarding the perceived prevalence of orthosis/arch support intolerance. However, the surveys show that the greatest number of delegates in both years voted "greater than 15 percent" of patients cannot tolerate arch supports on both questions, which is in agreement with the findings of my current study. Therefore, determining and reporting the prevalence of arch support intolerance would be timely and helpful for physicians and their patients.
Examining The Literature On Arch Support Intolerance
I reviewed 98 journal articles or text monographs in search of mention of intolerance of arch supports. I categorized the papers into three main topics known to have an impact on arch support intolerance: peroneal spastic flatfoot, sinus tarsi syndrome and tarsal coalition. Of the articles reviewed, 12 were flatfoot (or peroneal spastic flatfoot) oriented.1-12 Twenty-three were focused on sinus tarsi syndrome.13-35 Sixty-three studies involved tarsal coalitions.36–98
Unfortunately, none of the 98 articles or texts directly describe or report the patient response to supinating arch supports. However, 24 papers do mention or imply that supination or pronation was making the patient better or worse. Thus, it became necessary to infer that if the article reports that supination makes the patient worse and/or pronation makes the patient better, this is evidence within these articles for intolerance of arch supports or supinating devices.
Following this assumption, from the aforementioned review articles, three articles by Cowell and colleagues mentioned some connection of flatfoot to supination intolerance.3–5 However, it is noteworthy that in the 1972 Cowell and Elener article, there is admission that supinating devices helped some patients, which is similar to the finding from the Takakura and colleagues article on symptomatic talocalcaneal coalitions.5,92 In reference to the sinus tarsi articles, six of 22 articles implied arch support intolerance.13,14,22–24,35 Of the 63 articles I reviewed on tarsal coalition, 11 articles suggested intolerance of supination.38,41,43,48,49,55,70,77–79,90
I also observed that three of the 63 tarsal coalition articles discuss the more rare tarsal coalition with subtalar varus presentation. Simmons and colleagues reported three cases of tarsal coalition with varus foot and tibialis anterior spasm.86 One could speculate that arch supports/supinating devices likely would have helped these patients. However, Simmons and coworkers did not report treating these children with arch supports and therefore did not report response to arch supports or other conservative strapping/padding. Keh, Knapp and their colleagues report similar subtalar varus findings with tarsal coalition on one patient each.57,59
It is also of note that several articles mention conservative therapy for tarsal coalitions with the use of longitudinal arch supports, shoe inserts with arch supports, medial wedge, casting and a University of California Biomechanics Laboratory (UCBL)-type device, but these papers do not report the success or failure rates of the conservative measures. In their aforementioned study, Takakura and coworkers report that conservative therapy with arch supports helped some patients but they did not report patient response to pronation devices.92
To summarize the reviewed literature involving flatfoot, sinus tarsi syndrome and tarsal coalition, out of the 24 (of 98) articles mentioning or implying response to arch supports, 20 articles suggested that arch supports made the symptoms worse. Three articles that reported on a total of five cases regarding the topic of tarsal coalitions and suggested that arch supports would help.56,58,85 One article reported that arch supports helped some patients with tarsal coalition, without reporting the amount of arch support height and what degree of help the arch supports provided.92
As an interesting observation of this literature review, many authors described their patients as “asymptomatic” but did not report the symptom of arch support intolerance. Lysack and coworkers acknowledge solid evidence that many cases (20 to 75 percent) of radiographically demonstrated calcaneonavicular coalition involve patients who are completely asymptomatic.2,7,8,54,60,63,91 Neither Lysack and coworkers nor the authors they cited reported patient response to arch supports. Thus, the literature of the past has largely ignored the clinical symptom of arch support intolerance. Furthermore, none of the articles make any attempt at reporting or estimating arch support intolerance prevalence in the population.
A Closer Look At The Study Design And Arch Support Materials
The clinical portion of the study is a prospective, staged, single investigator, investigation to report the prevalence of arch support/orthotic intolerance. It is based on patients’ subjective responses. The intolerance portion of the study included 318 feet in 160 patients.
I recorded the patient’s chief complaint, secondary complaint, age, gender and non-weightbearing arch height. Group I consisted of patients who previously tried arch supports. Group II consisted of those who had never tried arch supports. Group II and a select number of Group I patients volunteered to try the study’s standard supinating arch supports. This select number of Group I participants who were willing to try the standard devices became Group III.
A few Select Group I patients were given pronating devices. These were the people for whom supinating arch supports made the pain worse but they were willing to try pronating devices, thus defining them as Group IV (see Table 1).
The study period began on Jan. 28, 2013 and continued until Aug. 18, 2013, and was inclusive of all consecutive new patients I saw at my main office.
Defining The Arch Supports The Study Used
The standard supinating arch support devices I used in the study were made from elastic rubber, 8.5 x 43 x 86 mm, which I arbitrarily gave a 50 percent arch height rating. I taped the devices to the patients using 3-inch flexible tape with the arch supports so they could remove the device when going to sleep or taking a bath/shower. I encouraged the participants to wear the devices for at least two weeks during waking hours.
The calcaneocuboid pronating devices were comprised of neoprene closed-cell material that was oval-shaped and 25 x 30 x 3 mm in size. Patients wore these devices with 2/3 plantar-proximal to the calcaneocuboid area and 1/3 rolling dorsally and laterally.
I dispensed standard supinating devices for 125 patients: 65 in Group II and 60 in Group III. There were 12 patients (Group IV) who received calcaneocuboid pads.
Upon the collection of subjective complaints, history and examination, 12 people had already determined that arch supports made their pain worse. These people were willing to try a pronating calcaneocuboid neoprene device instead of the standard arch support. When a patient clearly could not tolerate a supinating device, I subsequently ordered a pronating device. I made this clinical decision on the first date of presentation based upon the presenting complaint, degree of pain and location of pain, and history of previous arch support failure.
How the Patients Responded To The Arch Supports
Group I. Table 2 lists the five categories of devices I recognized in the study and Table 3 lists the Group I response to the five different grades of devices. Device A was a simple over-the-counter device in the 10 to 20 percent arch height range. Device B was a heat-molded foam/sporting goods device in the 30 to 40 percent range. Device C was the study’s “standard” device at 50 percent height. Device D was a mail order/TV commercial device in the 60 to 70 percent arch height range. Device E consisted of a Birkenstock device at 80 percent height and/or custom orthoses at a 90 to 95 percent height range.
Four patient subjective responses to the devices were recorded: 2=Made worse/intolerance, 3=No help, No worse either, 4=Help somewhat, 5=Work well. These four responses are consistent in the study and are to be noted in Figures 4,5 and 6 and in Table 6.
Five of 39 patients who used Device A reported the pain was worse. There were no patients using Device B who reported worse pain. Three of 11 patients using Device C had worse pain. Two of seven patients using Device D reported having worse pain. Ten of 30 patients using Device E noted the devices made their symptoms worse. This equates to a 21 percent intolerance (response 2) for Group I while arch supports helped 62 percent (responses 4 and 5). Seventeen percent responded with no help (response 3). Arch supports reduced pain for 62 percent of the patients in Group 1. Figure 3 shows this data graphically.
The 95 people in Group I would subsequently end up on one of three possible paths: a) receive standard arch supports (60 people, making up Group III); b) receive pronating calcaneocuboid pads (12 people, establishing Group IV); or c) 23 people who declined this part of the study. Twenty-one of those people who declined either were content with their current response and did not want to change, and two people said the devices they previously tried made their pain worse and they were not willing to put themselves through pain again.
An important recognition of the Group I patients is the reported uneven distribution of devices. Note that the greatest number of people in Group I (39) had tried the OTC 10 to 20 percent lifts (Table 6) followed by 30 people (32 percent) who had tried the 80 to 90 percent lifts. Only 27 percent of Group I participants had used a device in either category B, C, or D (lifts graded 30 to 70 percent). This uneven distribution reflects the possibly justified criticism that the findings in Group I may not be as valid as the findings in Groups II and III since each device category was not evenly populated.
Groups II and III. Both Groups II and III reflect response to the study standard devices, which were the same device for all 125 participants (see Figure 4). The responses indicate an intolerance of 18.5 percent (12 of 65) and 18.3 percent (11 of 60) for Groups II and III respectively. In Group II, arch supports helped 55 percent and in group III, arch supports helped 63 percent. Therefore, combining groups II and III together, 18.4 percent of the patients reported intolerance whereas 59 percent of patients noted that the arch supports were helpful.
Group IV. Twelve patients in group IV were dispensed calcaneocuboid pads. Six people said the pads made them feel worse, one person said the pain was no better and no worse, four people had some pain relief, and one person had considerable pain relief. These numbers are admittedly not statistically significant due to the small sample size. Suffice it to say that some participants were helped and others were not helped with the pronating device I used in the study.
Figure 5 shows a summary of group responses and combinations of Groups I, II, III. The lowest intolerance percentage was 18 percent in Groups II and III. The highest intolerance percentage was 21 percent for group I. Approximately 60 percent of the population reports that arch supports helped them.
What The Study Findings Reveal About Arch Supports
Since this is a study based on patient subjective responses, this is by nature an empirical study. Currently there are no reliable standardization studies regarding the effective functional arch lift of devices at the medial aspect of the human foot. It is intuitive that some devices give a 10 to 30 percent medial support to the foot, other devices support or lift the medial aspect of the foot 40 to 60 percent and other “custom made” devices support the medial arch at 90 percent or greater.
However, there has been no published review describing or defining categories where various supinating devices fall regarding arch height for over-the counter devices versus sham devices or prefabricated versus custom orthotics. This is why I attempted to place arch supports that participants of Group I previously tried into five categories based on arch height. I acknowledge that defining height categories in this manner is arbitrary but as there are no current standards of materials, support effectiveness and effective height, these five categories are starting points for comparison between supinating arch supports.
The study also acknowledges that some orthosis manufacturing companies argue that their devices are calibrated to improve the success of their orthoses and therefore these companies better pair their devices with the patient based on weight, foot flexibility, activity level, foam or plastic K-value (spring strength/resilience value).
However, the results of the current study suggest that there is a subset of patients who cannot tolerate arch supports regardless of fabrication material, effective height or calibration. Many people who cannot tolerate an orthosis cannot tolerate even a 10 to 20 percent device/lift as demonstrated by the Group 1, Device A, response 2 findings (see Table 6) in this study. Physicians who consider themselves knowledgeable prescribing supinating devices have experienced this intolerance.
Further, some physicians have observed that in some cases, a 20 percent arch height device yields more benefit/more comfort than a 90 percent device, yet these same physicians cannot always elucidate why this is the case. Regardless, those of us who prescribe and dispense custom devices to any degree of volume have had some patients who cannot tolerate our recommended devices, regardless of whether they are a 10 percent medial arch support or a 90 percent custom arch support.
Sometimes patients report that the doctor-prescribed supinating devices are "too tall" or "too hard,” are not helping the pain, and in fact are making the pain worse. Many of these patients describe “arch pain” with the devices. For many of these cases, some podiatric physicians, orthopedists or orthotists will attempt to reduce the medial height of the device.
In order to make the device more comfortable, physicians and orthotists will frequently perform the following. First, if the device is heat-moldable, the physician or orthotist will heat up the devices and shrink the medial aspect of the device to convert a 90 percent orthotic device to a 50 percent, 40 percent, or 30 percent device until patients can tolerate it. Second, if the device is an accommodative foam-type device, the physician makes similar attempts to decrease the medial height of the device by grinding or shaving the medial aspect, leaving the lateral aspect intact. However, it has been previously unknown what percentage of the population is likely to need the above adjustment.
This modification of the foot orthosis may not address what is causing the intolerance. It may just be an attempt to make the devices more tolerable, hopefully making the feet feel better and making the patient happy. With this orthotic or arch support-lowering protocol, physicians may have to accept that in some cases patients tolerate a thinner device more than a thicker/taller orthosis. The clinician frequently will realize that sometimes comfort is more important, even though a thinner device will not realign the foot as much as is clinically indicated. In other words, a taller orthosis may realign the foot significantly but if people will not use the device because they cannot tolerate the taller device, then patients will not benefit. The speculation here is that functional and therapeutic response in many cases depends on tolerance level.
If a physician or orthotist is required to lower the medial aspect of a supinating device for the foot, this is proof that the patient demonstrates the symptom of arch support intolerance. If one considers arch support intolerance to be insignificant, let us consider a quote regarding tarsal coalition by Outland and Murphy from 1960: "However, when one recalls the facility with which everyone missed such an obvious lesion as talosustentacular bar until Harris and Beath reported it, the bald assertion that a radiograph is negative will hardly be accorded great weight."11 I submit that Outland and Murphy’s observation regarding the importance of previously unrecognized evidence also applies to arch support intolerance some 58 years later. If we consistently screened patients for arch support intolerance, then baldly asserting that a patient is “asymptomatic” would occur much less frequently.
It is my impression that we could paraphrase Outland and Murphy's observation to apply this principle to arch support intolerance: “When one recalls the facility with which everyone missed such an obvious symptom of arch support intolerance until we started looking for it, then making the bald assertion that a patient with arch support intolerance is asymptomatic will hardly be accorded great weight.”
Arch support intolerance is an important symptom that we as physicians do not consistently record or recognize. As health care providers who consider ourselves patient advocates, we must consistently ask patients about their tolerance or intolerance of arch supports. Otherwise, we may be missing a large contributing factor to patient foot health. Before we can understand why some patients cannot tolerate arch supports, we first need to at least determine the prevalence. This is part of the reason why I conducted this study.
This study provides proof that arch support intolerance is prevalent in the podiatric community at a significant level. Arch support intolerance is a symptom, as many patients who have used arch supports demonstrate subjective evidence of physical disturbance with the devices. The study also reveals that some patients cannot tolerate arch supports regardless of the width of the device. Since only Groups II and III wore the same standard study devices, the 18 percent intolerance figure may be the most valid of the three supination groups. Regardless, the data suggests an arch support intolerance prevalence of 18 to 20 percent in the podiatric population.
Dr. McShane is in private practice at McShane Foot and Ankle Clinic in Springfield, MO. He is a Diplomat of the American Board of Podiatric Surgery, and a Fellow of the American Society of Podiatric Surgeons.
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