The Knee Injury Osteoarthritis Outcome Score (KOOS) is a widely used joint-specific measure employed to evaluate pain, symptoms, activities of daily living, recreational activities, and quality of life in patients with knee osteoarthritis (OA). Although the original KOOS has been translated into many languages, a Saudi Arabic version is not available. This study aimed to culturally adapt and evaluate the psychometric properties of the Saudi Arabic version of the KOOS in patients with knee OA. The original KOOS was translated and adapted into Saudi Arabic version over six stages according to the guidelines suggested by Beaton and recommended by the American Association of Orthopedic Surgeons Outcome Committee. Patients diagnosed with knee OA (n = 136) were recruited to examine the psychometric properties, such as internal consistency that was tested using Cronbach's alpha, test-retest reliability that was analyzed using the intra-class correlation coefficient (ICC2,1), and construct validity that examined by testing the correlations between the new version subscales, Form 36 Health Survey subscales, and the Visual Analog Scale, Spearman's correlation coefficient (rs) was used to measure the correlations. A total of 122 (89.7%) of the 136 participants with knee OA completed the second re-test of new Saudi Arabic version. Excellent internal consistency (Cronbach's alpha = 0.87-0.92) was detected in the subscales of the adapted version, as well as excellent test-retest reliability (ICC2,1 = 0.92-0.94). The pattern of correlation between the subscales of the Saudi Arabic version of the KOOS, SF-36 domains and the Visual Analog Scale for pain supported the construct validity of the adapted version. The Saudi Arabic version of the KOOS was well accepted and exhibited excellent reliability, internal consistency, and construct validity in Saudi patients with knee OA.
Keywords: Knee; Osteoarthritis; Psychometric; Reliability; Validity.