Italian version of the International Knee Documentation Committee Subjective Knee Form: cross-cultural adaptation and validation

PURPOSE: Patient-oriented measures, represented by self-administered questionnaires, have become an important aspect of clinical outcome assessment. To be used with different language groups and in different countries, questionnaires must be translated and adapted to new cultural characteristics, and then validated by a widely accepted process to evaluate reliability and validity, fundamental characteristics for each measure. The aim of the study was to perform the cross-cultural adaptation and to assess the reliability and validity of the Italian version of the International Knee Documentation Committee (IKDC) Subjective Knee Form. TYPE OF STUDY: A cross-cultural adaptation and cross-sectional study of a sample of patients undergoing anterior cruciate ligament (ACL) reconstruction with a subsample followed up prospectively for retest reliability. METHODS: The IKDC Subjective Knee Form was culturally adapted for Italian-speaking people, following the simplified Guillemin criteria. Reliability and validity were assessed in a cross-sectional study of 50 consecutive patients undergoing ACL reconstruction. A subsample of 20 patients was followed up prospectively for retest reliability. RESULTS: The results were compared with other validated patient-oriented measures. The principal IKDC scale showed a high correlation with other patient-oriented measures as hypothesized, and it also showed good values with regard to reproducibility, consistency, and validity, compared with the versions of IKDC published in other languages. CONCLUSIONS: These findings suggest that the evaluation capacities of the IKDC Italian version are equivalent to those of other language versions of the IKDC. LEVEL OF EVIDENCE: Level II.