Translation, cross-cultural adaptation and validation of the Italian version of the knee outcome survey-activities of daily living scale

Purpose: The Knee Outcome Survey -Activities of Daily Living Scale (KOS-ADLS) is a joint-specific questionnaire measuring symptoms and functional limitations experienced by individuals with painful knee disorders. The original version of the KOS-ADLS has been shown to be reliable, valid and responsive to change. The purpose of this study was to perform a translation and cross-cultural adaptation of the KOS-ADLS into Italian and to assess its reliability and validity.Methods: In accordance with standard procedures, the original version of the KOS-ADLS was translated and cross -culturally adapted into Italian (KOS-ADLS-I). Then, the KOS-ADLS-I was administered to 150 patients with knee disorders. A subsample of patients compiled the KOS-ADLS-I again after five/seven days later to evaluate test-retest reliability. Symptoms and function-oriented questionnaires were also completed to evaluate construct validity. Structural validity (Explanatory Factor Analysis [EFA]), internal consistency (Cronbach's alpha), test -retest reliability (Intraclass Correlation Coefficient [ICC]), measurement error (Standard Error of the Measure-ment [SEM], Minimal Detectable Change [MDC]), and construct validity (hypothesis testing) were assessed.Results: The cross-cultural adaptation procedure revealed no major problems. EFA revealed a unidimensional structure. Internal consistency was high (Cronbach's alpha = 0.976) and the test-retest reliability was excellent (ICC = 0.990, 95%CI: 0.980-0.995) with low measurement error (SEM = 2.6 points; MDC = 7.1 points). The construct validity resulted to be satisfactory, as 100% a-priori hypothesis were met.Conclusions: The KOS-ADLS-I is a reliable and valid questionnaire for the assessment of symptoms and functional limitations in individuals with musculoskeletal knee disorders and it can be used in clinical practice and research.