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

Abstract

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. 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. The translation from the source language to the target language, synthesis, back-translation, revision and pre-test 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. 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), Lequesne-daily 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). The Turkish KOOS-PS was found to be reliable and valid for patients with primary knee osteoarthritis.