Reliability and validity of the Turkish version of the knee injury and osteoarthritis outcome score-physical function short-form (KOOS-PS)

BACKGROUND: The Knee injury and Osteoarthritis Outcome Score-Physical function Short-form (KOOS-PS) is a disease-specific questionnaire that can be used to evaluate physical function in patients with knee problems and it has not been adapted to Turkish language. OBJECTIVE: The purpose of the present study was to adapt the KOOS-PS to the Turkish language and to evaluate the psychometric properties of the Turkish version of the KOOS-PS in patients with primary knee osteoarthritis. METHODS: The translation from the source language to the target language, synthesis, back-translation, revision and pretest stages were performed. A total of eighty patients participated in the study. Internal consistency was tested by Cronbach's alpha, test-retest reliability was tested by the intra-class correlation coefficient (ICC). Construct validity was investigated with Spearmann's rank correlation coefficient and correlations of the KOOS-PS with the WOMAC and Lequesne osteoarthritis indexes and with the duration of complaints, radiological grade and range of flexion were assessed for this purpose. RESULTS: Internal consistency was good, with a Cronbach's alpha of 0.904 and an ICC value of 0.839 certifying that the Turkish KOOS-PS is a reliable tool. Spearman's rank correlation coefficients between the KOOS-PS and the overall WOMAC (r = 0.764), WOMAC-physical function (r = 0.754), WOMAC-pain (r = 0.706), overall Lequesne (r = 0.775), Lequesnedaily living activities (r = 0.737) and Lequesne-pain (r = 0.716) were high. Moderate correlations were found between the WOMAC-stiffness, Lequesne-walking distance and KOOS-PS (r = 0.599 and 0.528, respectively). CONCLUSIONS: The Turkish KOOS-PS was found to be reliable and valid for patients with primary knee osteoarthritis.