Randomized Controlled Trial of Custom Foot Orthoses for Chronic Forefoot Pain

Condition(s) studied

Investigational drug(s) / intervention(s)

Podiatric advice: A podiatrist with 11 years of clinical experience will take the negative foot impressions using a semi-weightbearing method with a foam box for both groups to ensure adequate blinding of participants. Then, the foam boxes of the experimental group will be scanned so that the FOs can be 3D printed. Both groups will receive identical clinical guideline-based information and support at the beginning of the trial. The instructions will be as follows: (1) undertake a familiarization protocol of 14 consecutive full days (2) wear the FOs (customized or sham) at all time when they are standing (targeted minimum of 5 hours per day), (3) avoid positions that cause the metatarsophalangeal joints to dorsiflex (e.g., squatting or tiptoeing), (4) mechanical stress load management according to the tissue stress model, (5) do not walk barefoot and (6) wear shoes with good cushioning in which the FOs will be properly placed.

Customized foot orthoses: The customized foot orthoses will be manufactured with a Nylon-11 shell with 6° medially wedged forefoot-rearfoot posts (2.6 mm if the participants' weight (PW) is inferior or equal to 45 kg; 3.2 mm if 45\<PW\<100 kg; 4.0 mm if PW\>100 kg), a full-length 3 mm Poron top cover and a metatarsal pad (15 shore A) located 5 mm proximal to the metatarsal heads.

Sham foot orthoses: The molded sham FOs will be manufactured from 3 mm ethylene vinyl acetate. They will have an identical top cover material, color and a similar shape than the customized FOs, however, they will provide negligible mechanical support, considering the very low stiffness of their medial arch. The only impact of these FOs on plantar pressure is under the heel. These devices have been used as a sham condition in previous trials and a study has validated them as being credible.

Study summary

Background Chronic metatarsalgia (CM) causes significant pain and disability, affecting quality of life. Foot orthoses (FOs) including medially wedged designs with a metatarsal pad decrease excessive plantar pressure under the metatarsal heads, which is a suggested risk factor for developing CM. This FOs model may be effective in diminishing pain and improving function in these individuals. Thus, the objective of this trial will be to compare the effects of medially wedged FOs with a metatarsal pad and sham FOs on pain and foot function in individuals with CM.

Methods/design This participant- and assessor-blinded superiority randomized controlled trial (RCT) with two parallel groups will be conducted in Trois-Rivières, Canada. Sixty-four participants with CM will be recruited from the Université du Québec à Trois-Rivières outpatient podiatry clinic and via social media invitations. They will be randomized into intervention (customized FOs) or control (sham FOs) groups and will be evaluated at baseline and after 6 and 12 weeks. The primary outcome will be: (1) mean pain during walking for the most painful foot during the past week. The secondary outcomes will be: (1) Foot Function Index, (2) Global rating of change and (3) the 5-level EQ-5D.

Discussion Medially wedged FOs with a metatarsal pad are expected to provide a greater reduction in pain and improvement in foot function compared to sham FOs. This trial will help guide FOs prescription recommendations for managing foot pain in individuals with CM in the future.

Eligibility

Primary outcome measure(s)

• Mean pain during walking for the most painful foot during the past week — From Baseline to the end of follow-up at 12 weeks
  visual analog scale (from 0 to 10, 0 being no pain and 10 pain as bad as it could be).

Trial sites (1)

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