Translation, Cross-cultural Adaptation and Reliability of the Foot Posture Index (FPI-6) - Brazilian Version

Background: The Foot Posture Index (FPI) is a quick, easy, and reliable clinical assessment for measuring foot posture variation in different environments. The aim of the study was to translate the FPI into Brazilian Portuguese and assess its inter and intra-observer reliability. Methods: The cross-cultural adaptation of the 6-item version of the FPI (FPI-6) was accomplished using standard guidelines. Forty-two volunteers participated in the reliability process, assessed by two examiners and at three different occasions, evaluated using the intraclass correlation coefficient (ICC). The agreement between reliability assessments was investigated by the standard error of measurement (SEM) and the minimal detectable change (MDC90). Results: The Brazilian version of the FPI-6 showed excellent inter and intraobserver reliability for the dominant (ICC = 0.91 and 0.90) and nondominant lower limb (ICC = 0.94 and 0.92). The agreement was considered excellent for SEM with values representing less than 5% in relation to the total FPI-6 score. The MDC90 showed that changes in the score greater than 1.82 (for interobserver) and 1.90 (for intraobserver) can be considered as clinical changes in foot posture. Conclusion: The Brazilian version of the FPI-6 has proved reliable in terms of inter and intraobserver reliability and can therefore be used both in clinical practice and in scientific research.