Cross-cultural adaptation and reliability of the Foot Posture Index (FPI-6) – French version

Purpose The 6-item Foot Posture Index (FPI-6) is a reliable tool for the evaluation of foot deformities. Our aim was to translate and cross-culturally validate the FPI-6 for use in French-speaking countries and to determine the intra-rater and inter-rater reliability of the French version.Methods Cross-cultural adaptation was performed according to guidelines. Two clinicians assessed the FPI-6 in 52 asymptomatic individuals. We evaluated intra- and inter-rater reliability with the intraclass correlation coefficients (ICC), correlations (p-value < 0.05) and Bland-Altman plots. Standard error of measurement (SEM) and minimum detectable change (MDC95) were determined.Results For the cross-cultural adaptation, we modified several items of the FPI-6 user guide and added footnotes to ensure correct interpretation. ICC of the total FPI-6 scores were 0.94 to 0.96 for the intra- and inter-rater reliability for dominant and non-dominant lower limb. Correlations were significant (p < 0.001); r 0.88 to 0.92. Total score SEM was 0.68 to 0.78 and MDC95 was 1.58 to 1.82.Conclusions Intra- and inter-rater reliability of this French version of the FPI-6 was excellent for the total score and good to excellent for each item. The French FPI-6 can be used in French-speaking countries. The identification of SEM and MDC scores is useful for clinical interpretation.