The Knee Injury and Osteoarthritis Outcome Score (KOOS) is used to evaluate both immediate and long-term patient-relevant outcomes after a knee injury. Five outcomes are evaluated by the self-administered KOOS: pain, symptoms, daily living activities, sport and recreation function, and knee-related quality of life. The KOOS satisfies the fundamental standards for outcome measures and can be used to assess the course of knee injury and the effectiveness of treatment. The KOOS is administered by the patient, has an easy-to-use format, and takes about 10 minutes to complete.
Validity and Reliability
Users of the KOOS can have faith in the questionnaire’s construct validity, test-retest reliability, responsiveness, and content validity for subscales that are relevant to age and condition. Further research is needed to determine the concept validity of the KOOS-PS as well as the structural validity, cross-cultural validity, and measurement error. The presented guidelines can help researchers and physicians decide whether to use KOOS in patients with knee problems and in hierarchical testing of clinical trial endpoints (Collins et al. 2016)
Scoring and Interpretation
The KOOS questionnaire includes five dimensions that are relevant to patients: pain, symptoms, daily activities, sports and recreation, and quality of life. Each of these dimensions is scored separately, using a Likert scale with five possible answers ranging from 0 (no problems) to 4 (extreme problems). The scores for each dimension are calculated by summing the answers to the relevant questions. The resulting scores are then transformed to a scale from 0 to 100, with 0 representing extreme knee problems and 100 representing no knee problems. The scores on this scale represent the percentage of the total possible score that the person achieved.
Previously, each subscale may have up to two missing entries. At least 50% of the items must receive a response.
The following formulas are used to calculate each subscale score:
KOOS Quality of life:
KOOS Questionnaire Online Calculator
Roos, E. M., Roos, H. P., Lohmander, L. S., Ekdahl, C., & Beynnon, B. D. (1998). Knee Injury and Osteoarthritis Outcome Score (KOOS)–development of a self-administered outcome measure. The Journal of orthopedic and sports physical therapy, 28(2), 88–96.
Collins, N. J., Prinsen, C. A., Christensen, R., Bartels, E. M., Terwee, C. B., & Roos, E. M. (2016). Knee Injury and Osteoarthritis Outcome Score (KOOS): systematic review and meta-analysis of measurement properties. Osteoarthritis and cartilage, 24(8), 1317–1329.
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