The Knee Injury and Osteoarthritis Outcome Score -: a multifunctional questionnaire to measure outcome in knee arthroplasty

Aim: It was the purpose of this investigation to create a German version of the Knee Injury and Osteoarthritis Outcome Score (KOOS) and to test its appropriateness in patients with advanced gonarthritis. Method: Reliability (test-retest reliability, internal consistency), validity (convergent constuct validity and divergent construct validity), sensitivity to change as well as pacticability and acceptance of this questionnaire were tested in 90 patients. Results: The test-retest reliability was acceptably high for all subscales, it ranged between r = 0.65 and 0.78 and the questionnaire showed a high internal consitency in almost all of the subscales. The comparison to the results of the questionnaire "Short Form-12" (SF-12) as well as to the patients self-assessment of health status showed high concordance in nearly all subscales, however it was only moderate for the symptom scale. Furthermore the KOOS was able to show significant differences between patients and healthy controls. When testing the sensitivity to change, the KOOS could demonstrate significant improvements within 3 months and the instrument has shown to be practicable with a high acceptance by the patients. Conclusion: With the German version of the Knee Injury and Osteoarthritis Outcome Score a multidimensional instrument is available now to measure health status as well as therapeutic effects in patients with knee problems. Modifing the subscale "symptoms" could further optimize this questionnaire in patients with advanced gonarthritis.