Cross cultural adaptation, reliability and validity of the Greek version of Identification of Functional Ankle Instability (IdFAI) questionnaire

Abstract Background The objectives of our study were to develop the Greek version of the Identification of Functional Ankle Instability questionnaire (IdFAI) questionnaire and to evaluate its psychometric properties. Methods The IdFAI was translated and adapted into Greek according to the guidelines for cross-cultural adaptation of self report measures. It was tested for test-retest reliability, validity, internal consistency and floor-ceiling effects in 141 participants (54 males, 87 females; 23.5 ± 7.2 years). All participants were asked to fill the Greek IdFAI (IdFAI-GR), the Cumberland Ankle Instability Tool (CAIT), and the Lower Extremity Functional Scale (LEFS), in order to determine construct validity. To determine the test-retest reliability, fifty randomly selected individuals re-filled IdFAI seven days after the first session. Results The IdFAI-GR had high internal consistency (Cronbach alpha = 0.94) and excellent test-retest reliability (ICC2,1 = 0.97, SEM = 0.7). The IdFAI-GR had strong correlation with the CAIT (r = 0,7;p  Conclusion The Greek IdFAI questionnaire has proven to be a valid and reliable instrument to identify functional ankle instability. It can therefore, be used for both clinical and research purposes in Greek-speaking individuals.