To scan or not to scan? Comparing the effectiveness and cost differential of insoles manufactured from foam-box casts versus direct scans in treating musculoskeletal conditions of the foot and ankle: a double-blinded, randomised controlled trial.

Abstract

Background: Foot orthoses produced using computer-aided-design and manufacture (CAD/CAM) are commonly used to treat musculoskeletal conditions of the foot and ankle, however minimal evidence exists as to the most effective method used to capture the patients foot shape. This trial aimed to determine the effectiveness and cost of insoles manufactured from a direct scan of the foot compared with those manufactured from foam-box casts.

Methods: This double blinded clinical trial randomly assigned participants with lower limb musculoskeletal pathologies into two groups and provided them with custom CAD/CAM foot orthoses manufactured either from a direct scan of the participants' feet (direct scan group) or from foam-box casts of their feet (foam-box cast group). 114 participants were recruited and asked to wear their foot orthoses for 12-weeks. The Foot Health Status Questionnaire (FHSQ) was completed at baseline, 4, 8 and 12-weeks to evaluate the primary outcome measure of pain, as well as secondary outcomes for foot function, foot health and footwear, and the Orthotic and Prosthetic User Survey Client Satisfaction with Device module (OPUS-CSD) was completed at 12-weeks. Adherence was measured using a daily wear-diary recorded over 12-weeks. The number of manual insole adaptations was also recorded, and staff time, material and transportation costs were evaluated.

Results: 112 participants completed the trial. Despite no significant between-group differences, both groups reported significant improvements in pain, function and foot health from baseline to 4, 8 and 12-weeks, which all exceeded their respective minimum important differences. The direct scan group reported greater satisfaction at 12-weeks (p = 0.04), greater adherence (p < 0.001), and required less insole adaptations (n = 4) compared to the foam-box cast group (n = 15) (p = 0.006). Overall costs and staff time costs were higher in the foam-box cast group.

Conclusions: CAD/CAM insoles are effective in reducing pain, and improving foot function and foot health after 4-weeks, and sustained at 12-weeks, however the method of shape capture does not affect these responses. Over 12-weeks participant satisfaction and adherence was greater when using the direct scan approach, which also required fewer manual insole adaptations. There was a greater overall cost associated with foam-box insoles. Clinicians are therefore recommended to use direct foot scanning over foam-box casting when prescribing CAD/CAM insoles for patients with musculoskeletal foot and ankle conditions.

Trial registration: ClinicalTrials.gov, trial number NCT05444192. Trial registration date 30th June 2022.