Reliability, validity and responsiveness of the Spanish version of the Knee Injury and Osteoarthritis Outcome Score (KOOS) in patients with chondral lesion of the knee.

PURPOSE: The purpose of this study was to perform a cross-cultural adaptation of the Knee Injury and Osteoarthritis Outcome Score (KOOS) into Spanish and to evaluate the psychometric properties of this version in patients with chondral lesion of the knee, as expressed by its validity, reliability and responsiveness.
METHODS: The translation followed an established forward-backward translation procedure with independent translations and counter-translation, according to the recommendations for the cross-cultural adaptation of HRQL measures. Twenty Spanish-speaking patients who underwent arthroscopic surgery for knee cartilage defects with a microfracture technique were enrolled in the study. Diagnosis was made based on clinical criteria and radiological confirmation through magnetic resonance imaging. Patients showing signs of instability, axial malalignment or generalised knee osteoarthritis were excluded from the study.
RESULTS: Cronbach's alpha value for the study of the questionnaire was >0.7 in all the KOOS domains except for Symptoms domain. The test-retest reliability was confirmed with an ICC value greater than 0.8 in all the KOOS domains. A significant agreement between the KOOS domains and the scales of the SF-36 with related content, particularly in the areas of physical function and pain, was observed.
CONCLUSION: Spanish KOOS questionnaire is valid, reliable and responsive for use in Spanish patients with symptomatic chondral lesion of the knee receiving surgical intervention.