Reliability, validity, and responsiveness of the simplified Chinese version of the knee injury and Osteoarthritis Outcome Score in patients after total knee arthroplasty

Objectives: The Knee Injury and Osteoarthritis Outcome Score (KOOS) has been utilized to evaluate short- and long-term outcomes in individuals following knee injuries, such as those with anterior cruciate ligament reconstruction and knee osteoarthritis, but has not yet been applied to individuals undergoing total knee arthroplasty (TKA) in China. The aim of this study was to assess the psychometric properties of the Simplified Chinese version of the KOOS in Chinese individuals undergoing TKA. Methods: This study distributed 170 questionnaires, and assessed the KOOS of the participants, along with requiring them to complete the Short Form 36 (SF-36) survey. There were 35 participants completed a test-retest reliability survey with a 24-h interval, 129 participants completed a pre - surgery survey, and 119 individuals completed a post - surgery survey 6 weeks after the surgery. The following tests were conducted: Cronbach's alpha (alpha) to assess internal consistency, intraclass correlation coefficient (ICC) to evaluate test-retest reliability, Spearman's correlation coefficient (rho) to examine construct validity, effect size (ES) to detect measure responsiveness, minimal detectable change (MDC) to assess measurement errors. Floor and ceiling effects (<15%) were also asses evaluated. Results: The simplified Chinese version of the KOOS showed good test-retest reliability in participants after TKA, with an ICC of 0.82-0.97 (95% CI). The internal consistency of the five subscales of the KOOS was good (Cronbach's alpha = 0.70-0.96). No floor or ceiling effects were found. Regarding construct validity, a strong positive correlation was found between each of the three KOOS subscales (activities of daily living, knee-related Quality of Life, and sport and recreation subscales) and the general health and bodily pain subscales of the SF-36 (0.53 < rho < 0.61). The subscales of the simplified Chinese version of the KOOS showed responsiveness (ES: 0.68 to 0.86) before and after 6 weeks of physical treatment. The MDC ranged from 10.28 to 23.24. Conclusions: The Chinese version of the KOOS showed good psychometric properties and was found to be valid, reliable, and simple as an assessment tool for symptoms, pain, activity of daily living, sports and recreational activity and quality of life for the Chinese population suffering from TKA.