The first study by Pfeffer [14] was a well-publicized study that compared the effectiveness of stretching alone to stretching in combination with one of four different shoe inserts in the treatment of plantar fasciitis. Shoe inserts included three prefabricated pads (silicone heel pad, ¾-length felt pad, rubber heel cup), and custom foot orthoses. Though the conclusion states that prefabs along with stretching “is more effective than custom orthoses,” an analysis of the statistics shows that all five treatment groups had an improvement in both pain scales, with no significant difference among the groups in the reduction of overall pain scores after 8 weeks of treatment when controlled for covariates. This misleading conclusion prompted a deeper look into the study details to determine why the authors would have made a statement that was not supported by their data.

A retrospective analysis of this work shows that the device type was not consistent. Forty-five percent of the custom orthoses were rigid polypropylene (normal width, 14–16 mm heel cup, no posts or top covers). Another 38% were identical except that the flexibility was semirigid. The flexibility variance was not evaluated in this study, nor mentioned as a variable that could affect outcomes. The remainder of the orthoses (17%) varied dramatically. Variables other than shell flexibility that were altered included heel cup depth (range 8–18 mm), width (narrow–wide), use of a rearfoot post, and use of a top cover. The authors noted that patients were encouraged not to change their regular shoe wear. Did the authors believe that a narrow device with a 8 mm heel cup was equivalent to a wide device with a 18 mm heel cup for a patient with plantar fasciitis, or were they accommodating the patient’s shoe choice as limited by their protocol? Improper footwear has been identified as a contributing factor in plantar fasciitis [15].

Another variable with the orthoses in this study involves the negative cast. Custom orthosis studies generally allow only a single experienced practitioner to cast each patient, minimizing any effect of the casting process on orthosis outcomes. It appears that 13 different practitioners casted the 42 subjects, with these practitioners learning to cast by watching a video. Considering the number of uncontrolled variables in the custom orthoses group, it is unclear how the authors drew any conclusions about the efficacy of custom orthoses in the treatment of plantar fasciitis, or justified a comparison to the other treatment groups. Fortunately, there have been other outcome studies in the treatment of plantar fasciitis.

Another positive evaluation of custom orthotic therapy for plantar fasciitis by Lynch [16] evaluated the effect of three widely accepted treatments: anti-inflammatory (injected and oral NSAIDs), accommodative (viscose heel cup and acetaminophen), and mechanical (low-Dye strapping followed by custom foot orthoses). This randomized prospective study found that 70% of the patients in the mechanical therapy group had improvements in pain and function, significantly better than the accommodative (30%) or the anti-inflammatory (33%) groups. Only 4% of the mechanical group had treatment failure, as opposed to 42% for the accommodative group and 23% for the anti-inflammatory group. The authors concluded that mechanical control with custom orthoses is more effective than anti-inflammatory therapy or accommodative therapy used in this study.

Martin [17] published a prospective randomized study that evaluated the effectiveness of three different mechanical modalities used in the treatment of plantar fasciitis including over-the-counter arch supports, rigid custom-made orthoses with a heel post, and night splints. Though all three devices were effective as initial treatments for plantar fasciitis after 12 weeks of use, “there was a statistically significant difference among the three groups with respect to early patient withdrawal from the study due to continued severe pain, noncompliance, or inability to tolerate the device. Patient compliance was greatest with the use of custom-made orthoses.”

Langdorf [18] conducted a randomized trial that evaluated the short-term and long-term effectiveness of foot orthoses in the treatment of plantar fasciitis. The three treatment arms were: sham orthosis made of soft, thin EVA foam molded over unmodified plaster cast, prefabricated foot orthosis made from firm density polyethylene foam, and Root functional custom foot orthosis . Both the prefabricated orthoses and the custom orthoses produced statistically significant improvements in function at 3 months. The authors noted that more participants in the sham group and the prefabricated group broke protocol than in the custom group.

Roos [19] evaluated the effect of custom-fitted foot orthoses and night splints, alone or combined, in treating plantar fasciitis in a prospective randomized trial with 1-year follow-up. The authors concluded that custom foot orthoses and anterior night splints were effective both short-term and long-term in treating pain from plantar fasciitis with all groups improving significantly in all outcomes evaluated across all times. “Parallel improvements in function, foot-related quality of life, and a better compliance suggest that a foot orthosis is the best choice for initial treatment of plantar fasciitis.”

A Cochrane database review and a meta-analysis both published in 2008 attempted to evaluate the evidence of orthoses reducing pain in patients with plantar fasciitis [20, 21]. Five trials, which included 691 participants, demonstrated that “although there is limited evidence on which to base clinical decisions regarding the prescription of custom-made foot orthoses…there is silver evidence for painful plantar fasciitis and hallux valgus” [21].

The meta-analysis focused on the randomized controlled trials or prospective cohort designed studies containing self-reported improvement in pain in patients with plantar fasciitis. The conclusion of the report stated “the use of foot orthoses in patients with plantar fasciitis appears to be associated with reduced pain and increased function” [20].

Lastly, a presented but unpublished (or) in press report by Wrobel attempted to associate custom, prefabricated and sham orthoses with reduced pain and improved activity. The study includes 77 participants who were monitored on various measures. Although all groups reported improvement in morning pain, the custom orthotic group had a spontaneous increase in physical activity wearing their orthoses [22].

Although at first glance the data on the efficacy of orthotic therapy for plantar fasciitis in the athlete appears conflicting, every study supports the use of custom orthoses. Each study leaves little doubt that this pathology is mechanical in origin and effective treatment is accomplished through mechanical control by custom orthoses. Future research may shed light on which modifications of custom orthoses may be most effective in controlling the midtarsal joint motion to prevent stretching of the plantar fascia.