Randomized Controlled Trial of Custom Foot Orthoses for Chronic Forefoot Pain

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.

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.

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.