July 2011

Plantar fasciitis: A new take on custom orthoses

Figure 1. A temporary thermoplastic custom foot orthosis was casted in a plantar flexed and inverted position.

The medical literature generally supports the use of foot orthoses for management of plantar fasciitis symptoms, but evi­dence regarding specific orthotic designs is inconclusive. Early research suggests a temporary custom foot orthosis may be an effective treatment option.

By Caryn Doggett, DPT, Michelle Drake, DPT, and Robert Boyles, PT, DSc, OCS                 

Plantar fasciitis (PF), also referred to as heel pain syndrome, jogger’s heel, tennis heel, and calcaneodynia, is clinically defined as pain and tenderness under the heel during weightbearing leading to a limitation of activities.1 In some individuals it can be a source of pain for months and even years.1 PF is the most common foot complaint in the U.S., affecting approximately 10% of people during their lifetime.2 It accounts for more than 1 million annual physician visits in the U.S., and is the most common foot condition seen in outpatient physical therapy clinics.2-4

The plantar fascia is a thick fibrous connective tissue that provides dynamic shock absorption and static support of the longitudinal arch. Three primary bands make up the plantar fascia. The central band originates at the medial tubercle of the calcaneus and inserts into the proximal phalanx of toes 2 through 5.2 The lateral and medial bands originate from the abductor digiti minimi and abductor hallucis muscles, respectively, and are continuous with the central band and dorsal fascia.5

Symptoms of PF are usually insidious and include periods of sharp pain, generally experienced with the first step in the morning or after prolonged periods of nonweightbearing activities. Symp­toms may also manifest as a dull discomfort or deep ache at the origin of the plantar fascia near the inferior medial calcaneus.6

Evidence for PF treatment

The majority of past research has viewed PF as an inflammatory disorder thought to result from microtearing of the plantar fascia. New evidence, however, shows no inflammatory properties present in histological studies of individuals with chronic PF, but, rather, suggests PF is a degenerative condition affecting the collagen fibers.6,7 This new evidence may cause practitioners to reconsider anti-inflammatory pharmaceutical management of chronic cases, which has traditionally been the first line of treatment.6

Although the exact etiology of PF is unclear, most sources agree that it results from overuse secondary to various anatomical, environmental, and biomechanical risk factors. These may include pes planus, pes cavus, limited ankle dorsiflexion, obesity, prolonged weightbearing activities, inadequate stretching, poor footwear, trauma, weak plantar flexor muscles, and excessive subtalar joint pronation.8 Among these factors, limited ankle dorsiflexion is associated with the highest odds ratio for developing PF (23.3, confidence interval, 4.3 to 124.4).6,9

Due to the multifactorial nature of PF, clinicians must consider various factors when choosing a treatment approach for individual patients. The first form of treatment is general education from the primary care physician regarding pain-free activities and possible etiologies.10 If pain does not resolve in four to six weeks, the patient may be referred to a physical therapist, podiatrist, or foot specialist for any of a number of additional treatments. These may include electrophysical agents, shockwave therapy, nonsteroidal anti-inflammatory drugs, manual therapy, stretching, taping, night splints, corticosteroid injections, foot orthoses, or combined treatments. Surgery is an option for those with recalcitrant PF.8,10-11

Evidence regarding foot orthoses

Foot orthoses are often used for the treatment of PF. This line of treatment is supported by both patient reports and biomechanical theory. Studies have demonstrated that excessive pronation and lower arch shape, in addition to repetitive trauma and overuse, can increase tension on the plantar fascia, leading to pain.12-14 Orthoses are believed to reduce the strain on the plantar fascia and provide foot support.15-17 This should lead to an overall decrease in medial heel and arch pain.

Previous research has demonstrated high self-reported symptom relief and increased patient satisfaction when using foot orthoses.3,18 One of the main weaknesses within each of these studies was the lack of a control group comparing the participants who had received foot orthoses to participants receiving a sham treatment or another form of treatment for PF. However, in 1997, Caselli et al published a randomized controlled trial (RCT) that provided orthoses to all participants, leaving the reader to believe orthoses are effective in treating PF.19 The primary focus of this article was on the effectiveness of magnetic foil with orthoses rather than orthoses alone.19

Other RCTs focusing on the effectiveness of orthoses alone followed Caselli et al’s 1997 study. They found that foot orthoses are effective in treating PF.3,6,12,20-25 Along with this evidence, Rome et al24 collected data from 48 participants evaluating the func­tional- and cost-effectiveness of functional versus accommodative ortho­ses. They found that while the functional orthoses were more expensive, they resulted in a better quality of life.24

At this time, RCTs are trying to answer two questions: First, are foot orthoses effective in treating plantar fasciitis in the long term, and second, what is the relative efficacy of prefabricated (over-the-counter) foot orthoses versus customized foot orthoses? The significant cost difference, which can range up to hundreds of dollars, between the two types of orthoses is reason enough for the latter question. The strongest research at this time suggests that foot orthoses, regardless of type, are beneficial in reducing short-term pain relief and foot disability.3,6

The RCTs that offer the strongest support for orthotic management of PF at this time include articles by Pfeffer et al, Lynch et al, Martin et al, Turlik et al, Landorf et al, and Baldassin et al.

Pfeffer et al21 examined 236 participants with chronic PF who were randomized to five different treatment groups: calf stretching only, stretching combined with a silicone heel pad, stretching combined with a felt pad, stretching combined with a rubber heel cup, or stretching combined with a custom-made functional foot orthosis. The authors concluded that prefabricated foot orthoses plus stretching were more effective in treating PF after eight weeks than custom-made orthoses plus stretching or stretching alone.

Lynch et al20 analyzed 103 participants with chronic plantar heel tenderness who were randomized to three different groups: anti-inflammatory therapy, an accommodative viscoelastic heel cup, or low-Dye strapping followed by custom-made orthoses. After three months, the mechanical treatment group (custom-made orthosis and low-Dye strapping) had the greatest reductions in pain and the fewest dropouts, although the extent to which this can be attributed to taping in addition to orthoses is unclear.

Martin and colleagues22 randomly assigned 193 participants with chronic plantar heel tenderness to receive a custom orthosis, over-the-counter arch support, or a night splint. At three month follow-up, there were no statistically significant differences in pain reduction between the three groups, suggesting custom orthoses, prefabricated orthoses, and night splints all have similar outcomes for patients with PF.

Turlik et al23 randomized 60 patients with chronic PF to receive generic heel pads or custom functional foot orthoses. After three months of treatment, both groups experienced a reduction in duration and severity of treatment, but those in the custom group had significantly better outcomes than those in the heel pad group. However, the reliability and validity of the outcome assessment tool used in this study are unclear, and the two groups were not matched for body weight at baseline.

Landorf et al18 randomized 135 participants with PF to receive a sham orthosis (soft, thin foam), a prefabricated orthosis (firm foam) or a customized orthosis (semirigid plastic). At three- and 12-month follow-up visits, the researchers found the prefabricated and customized orthoses produced small short-term benefits compared with the sham orthosis. They concluded that the long-term effects of orthoses on pain and function with individuals with PF are negligible.

Baldassin et al12 examined 142 individuals with PF and randomly assigned participants to receive either a custom-made orthosis or a prefabricated orthosis. After eight weeks of utilization,
both treatment methods were associated with significant pain reduction and there was no significant difference between the custom-made and prefabricated orthoses groups.

Although these trials have limitations, overall they provide a stronger foundation for this line of treatment than was available prior to 1997, suggesting that both custom and over-the-counter foot orthoses are indeed effective for treating pain for individuals with PF.2,8,12,21,20-23

Our research

Lacking in the literature at this time are illumination of two factors—the most effective material type for the orthosis and optimal positioning of the orthosis. Ethylene vinyl acetate (EVA), rubber, vinyl, thermoplastic, leather, PPT, silicone, felt, Polydur plastic, viscoelastic, and many other materials have been utilized to
fabricate foot orthoses for treating plantar fasciitis.1,3,13,21,22,26,27 To our knowledge, there are no studies comparing orthotic materials with regard to clinical effectiveness or cost effectiveness. Nor, to our knowledge, is there any research that looks at the foot being casted in a position other than subtalar neutral.

Our research team recently completed a study8 on the effects of creating a temporary custom foot orthosis casted in a plantar flexed and inverted position using Aquaplast, a thermoplastic material. We found this orthotic technique to be successful for short-term pain relief and disability in all of the study participants, who were diagnosed with chronic plantar fasciitis. No previous research has been done on this type of intervention.

The aim of our study was to determine if two weeks of wearing a temporary custom foot orthosis in a near-end range plantar flexed and inverted position followed by a stretching program would decrease participants’ first-step pain in the morning and increase foot function. We hypothesized that positioning the foot in plantar flexion and inversion during all periods of weightbearing would decrease tension on the plantar fascia. This, in theory, would prevent repetitive microtearing and allow for healing of the plantar fascia, reducing pain and increasing function.

We placed fliers around the community and obtained a convenience sample of 15 participants who met the inclusion criteria. Of importance is that each participant had first-step pain along with either a positive reproduction of symptoms at the plantar fascia insertion or a positive windlass test.2

Figure 2. Mean Numeric Pain Rating Scale (NPRS) scores at all collection points with standard deviations.

We then fabricated orthoses for these participants on day one. They received the temporary custom foot orthosis (TCFO) and were instructed to wear it for all weightbearing activities during a two-week period. Each participant received one TCFO for the affected foot only or one pair if there was bilateral involvement. The participants had follow-up appointments at two, four, and 12 weeks
after the initial appointment. After two weeks of TCFO alone, TCFO weaning began and a daily ankle and plantar fascia stretching program was initiated.

During each of the four participant visits (baseline, two, four, and 12 weeks) we had each individual fill out the following outcome measurement forms: Numeric Pain Rating Scale (NPRS) for rating their pain with first step, and the Foot and Ankle Ability Measure (FAAM) which measures the functional abilities through two
subscales: activities of daily living (FAAM-A) and sports (FAAM-S). Each outcome has been proven to be reliable and valid for heel pain22,28 and used in previous heel pain studies. Our secondary outcome was patient-reported improvement based on the Global Rating of Change (GRC) scale, which was completed at two, four, and 12 weeks. Juniper et al29 proposed the following classifications based on a patient’s GRC score: 0, 1, or -1 indicates no change; 2 or 3 indicates minimal change; 4 or 5 indicates moderate change; and 6 or 7 indicates a large change in the condition.

The average age of the participants (13 women, 2 men) was 37.6 years. Participants reported an average pain level of 5.5 out of 10 and had experienced the chronic heel pain for an average of 20 months. No participants had to withdraw from the study due to complications or the inability to tolerate the orthosis. Repeated-measure analyses of variance (ANOVAs) revealed statistically significant changes at all three follow-up times compared with baseline for all three primary outcomes (NPRS, P<0.001; FAAM-A, P=0.001; FAAM-S, P<0.0001). Additionally, mean GRC score was clinically meaningful for positive changes in participants’ changes at two, four, and 12 weeks.

Figure 3. Global Rating of Change (GRC) scores at all data collection points with standard deviations

To the best of our knowledge, no research has been conducted using temporary foot orthoses. The TCFO is designed to temporarily off-load and protect the injured area and allow for plantar fascia healing. Once weaned from the TCFO the foot is returned to its normal resting position. Stretching exercises are regularly per­formed with the goal of permanently managing pain and preventing future occurrences.

Most foot orthoses are prescribed for longer wear periods (>8 weeks).12,18,21,22,25 The two-week time frame used in our research was arbitrary, based on the average response time for the reparative processes to occur and estimated time it would take to prevent repetitive microtearing and re-injury. After two weeks most cellular responses to injury have begun. The following weeks focus on maturation and remodeling of tissue as well as gaining tissue strength.30 Patients were advised to continue wearing the TCFO until symptoms resolved, but no participants in our study required use beyond two weeks. Future research would be needed to determine if participants would experience greater and more durable improvements with a TCFO wear period longer than two weeks.

The overall conclusion of our study suggests that patients with chronic plantar fasciitis or heel pain may benefit from a temporary custom foot orthosis fabricated in a plantar flexed and inverted position followed by stretching for short-term relief of their heel pain and an increase in functional activities. Our study does not show cause and effect, but the conclusions and findings are strong enough to warrant an RCT, which is currently being completed.

Conclusion

Plantar fasciitis affects 10% of the general population and limits personal activities in many individuals, including running, hiking, standing, and working. There is a steady stream of published research regarding a variety of treatments for plantar fasciitis, including foot orthoses. Foot orthoses vary in material, price, foot position for molding, and wearing time. At this time, research has not demonstrated superiority for any specific orthotic characteristics related to these factors; however, it does suggest that foot orthoses are an effective short-term treatment for plantar fasciitis.

We were able to demonstrate in a small nonrandomized trial that an intervention using a quick inexpensive custom orthosis decreased first-step pain, increased function, and provided an overall self-reported positive change in this patient population. We are conducting an RCT to test this intervention on a larger patient population.

Caryn Doggett, DPT, is a traveling physical therapist in the San Francisco Bay Area. Michelle Drake, DPT, is a staff physical therapist at Chugach Physical Therapy in Anchorage, AK. Robert Boyles, PT, DSc, OCS, FAAOMPT, is a clinical associate professor of physical therapy at the University of Puget Sound, Tacoma, WA.

Disclosure: The authors affirm that they have no financial affiliation (including research funding) or involvement with any commercial organization that has a direct financial interest in any matter included in this manuscript.

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