Chinese cross-cultural adaptation and validation of the Foot Function Index as tool to measure patients with foot and ankle functional limitations

Purpose: To perform a cross-cultural adaptation and validation of the Foot Function Index (FFI) questionnaire to develop the Chinese version.Materials and methods: Three hundred and six patients with foot and ankle neuromusculoskeletal diseases participated in this observational study. Construct validity, internal consistency and criterion validity were calculated for the FFI Chinese version after the translation and transcultural adaptation process.Results: Internal consistency ranged from 0.996 to 0.998. Test-retest analysis ranged from 0.985 to 0.994; minimal detectable change 90: 2.270; standard error of measurement: 0.973. Load distribution of the three factors had an eigenvalue greater than 1. Chi-square value was 9738.14 (p<0.001). Correlations with the three factors were significant between Factor 1 and the other two: r=-0.634 (Factor 2) and r=-0.191 (Factor 1). Foot Function Index (Taiwan Version), Short-Form 12 (Version 2) and EuroQol-5D were used for criterion validity. Factors 1 and 2 showed significant correlation with 15/16 and 14/16 scales and subscales, respectively.Conclusions: Foot Function Index Chinese version psychometric characteristics were good to excellent. Chinese researchers and clinicians may use this tool for foot and ankle assessment and monitoring.Implications for rehabilitationA cross-cultural adaptation of the FFI has been done from original version to Chinese.Consistent results and satisfactory psychometric properties of the Foot Function Index Chinese version have been reported.For Chinese speaking researcher and clinician FFI-Ch could be used as a tool to assess patients with foot disease.