Validation of a Chinese translation of the identification of functional ankle instability questionnaire

To the Editor:Ankle sprains account for about 40%of all sports injuries,and 20%to 33%of ankle sprains will cause ankle instability.[1]Functional ankle instability(FAI)does not yet have an accurate and widely accepted measurable definition,although many surgeons have treated it for years when it is combined with anterior talofibular ligament injury,calcaneofibular ligament injury,or both.In China,some unnecessary ligament-repairing surgeries may be performed just because of imaging evidence of ligament injury and possible(but not sure)FAI,leading to some unsatisfactory results.Several self-reported questionnaires have been developed to help define FAI but no validated Chinese version existed,although China has the highest number of patients with FAI.The International Ankle Consortium has recommended the Ankle Instability Instrument,the Cumberland Ankle Instability Tool,and the Identification of Functional Ankle Instability(IdFAI)questionnaire,which is based on the first two questionnaires,to assess FAI.[2]The IdFAI has the highest accuracy of the three questionnaires.[3]The original English version of IdFAI has been translated into many languages,and the Japanese,Korean,Brazilian,and Persian versions have been validated.We developed a Chinese version of the IdFAI(IdFAI-C)and determined its validity by assessing its discriminate validity,internal consistency,accuracy,and test-retest reliability.