Effects of custom insoles for symptomatic hallux valgus: protocol for a sham-controlled randomised trial

INTRODUCTION: Hallux valgus (HV) is one of the most prevalent forefoot deformities, and its frequency increases with age, reaching nearly 23% in adulthood (females are usually more affected). Studies on customised insoles and orthoses for HV showed inconclusive results. There is no consensus in literature regarding the ideal insole or length of use for pain relief or functional improvement in individuals with HV. This study will assess the effects of a customised insole with retrocapital bar associated with an infracapital bar of the first metatarsal on pain and function of individuals with symptomatic HV. METHODS: This is the protocol for a blinded, sham-controlled randomised clinical trial. Eighty participants with symptomatic HV will be randomised into two groups (40 per group): customised insole or sham insole. Assessments will be performed at baseline (T0), six (T6) and 12 weeks (T12) of intervention. A follow-up will occur after 4 weeks of intervention (T16). The primary and secondary outcomes will be pain (Numerical Pain Scale) and function (Foot Function Index), respectively. STATISTICAL ANALYSIS: Analysis of variance with a mixed design or Friedman’s test will be considered according to data distribution; post-hoc analyses will be performed using Bonferroni test. Time × group interaction and within-group and between-group differences will also be assessed. The intent-to-treat analysis will be used. A significance level of 5% and 95% s will be adopted for all statistical analyses. ETHICS AND DISSEMINATION: This protocol was approved by the research ethics committee of the Faculty of Health Sciences of Trairi/Federal University of Rio Grande do Norte (UFRN/FACISA; opinion number 5411306). The study results will be disseminated to participants, submitted to a peer-reviewed journal and presented in scientific meetings. TRIAL REGISTRATIONS NUMBER: NCT05408156.