Comparing the effectiveness of computer-aided-design/computer-aided-manufacture (CAD/CAM) insoles manufactured from foam-box cast versus direct scans on patient reported outcome measures: A protocol for a double-blinded, randomised controlled trial

Abstract

Introduction
Custom insoles are a routine treatment for many foot pathologies, and the use of computer aided design and manufacture (CAD/CAM) is well established within clinical practice in the UK. The method of foot shape capture used to produce insoles varies throughout orthotic services. This trial aims to investigate the effectiveness of two common shape capture techniques on patient reported outcomes in people who require insoles for a foot or ankle pathology.
Methods and analysis
This double blinded randomised controlled trial will consider two intervention groups recruited from a National Health Service orthotic service. Participants will be randomly assigned to receive a pair of custom CAD/CAM insoles, manufactured either from a direct-digital scan or a foam-box cast of their feet and asked to wear the insoles for 12-weeks. The primary outcome measure will be the Foot Health Status Questionnaire (FHSQ) Pain sub domain, recorded at baseline (immediately after receiving the intervention), 4-weeks, 8-weeks, and 12-weeks post-intervention. Secondary outcome measures will include FHSQ foot function and foot health sub domains recorded at baseline, 4-weeks, 8-weeks, and 12-weeks. The Prosthetic and Orthotic User Survey Satisfaction with Device Survey recorded after 12-weeks. Transit times associated with each arm measured as the number of days for each insole to be delivered after foot shape capture. Tertiary outcome measures will include participant recruitment and dropout rates, and intervention adherence measured as the daily usage of the insoles over 12-weeks. The change in FHSQ scores for the sub-domains and insole usage will be compared between the groups and time points, and between group differences in time-in-transit, cost-time analysis and environmental impact will be compared.
Ethics and Dissemination
Ethical approval was obtained from the Health Research Authority, London Stanmore Research Ethics Committee (22/LO/0579). Study findings will be submitted for publication in peer-reviewed journals, conference presentations and webinars.
Protocol version: Version 2, 08/092022
Trial registration: ClinicalTrials.gov (Trial number NCT05444192)
Strengths and limitations
• This trial aims to investigate routine interventions that are used within the NHS, therefore the outcomes have the potential to impact on the decision making within orthotic services across the UK and beyond.
• The double blinded design reduces the risk of bias from the participant and the investigator.
• Single centre design may limit the cohort.
• The multiple follow-up points may lead to drop outs.