Foot Function Index for Arabic-speaking patients (FFI-Ar): translation, cross-cultural adaptation and validation study

Background Foot Function Index (FFI) is a valid and reliable outcome measure, which is widely used to measure the foot and ankle functional level and disorders. Until now, no validated Arabic version of the FFI is available. This study was conducted at a tertiary care hospital in Riyadh, Saudi Arabia. The purpose of this project was to translate and adapt the FFI into Arabic and to evaluate its psychometric properties of validity and reliability. Methods The study consisted of two phases. The first phase was the translation and cultural adaptation of the FFI to Arabic. The next phase involved, testing the psychometric properties of the Arabic version of the FFI on a sample of 50 consecutive participants which included internal consistency, test-retest reliability, floor and ceiling effects and construct validity. Results The mean age of the study participants was 38 +/- 12.94 years. Both the genders were evenly enrolled with 50% of the participants as male and 50% as female. Majority of them complained of plantar fasciopathy (32%) followed by pes planus (22%) and ankle sprain (18%). The scores of FFI-Ar were normally distributed, confirmed by a significant Shapiro-Wilk test. The mean value of FFI-Ar total score was 47.73 +/- 19.85. There were no floor or ceiling effects seen in any of the subscales and total score. The internal consistency was good with the Cronbach's alpha value of 0.882, 0.936 and 0.850 for the pain, disability and activity limitation subscales, respectively. The reproducibility of the FFI-Ar was analysed by intra-class correlation coefficient which revealed good to excellent test-retest reliability. A significant correlation was found between FFI-Ar and SF-36 and numeric rating scale (NRS) confirming its construct validity. Conclusion The FFI-Arabic version showed good validity and reliability in patients with foot and ankle problems. This tool can be used in usual practice and research for analysing foot and ankle disorders in Arabic-speaking people.