Knee Injury and Osteoarthritis Outcome Score or International Knee Documentation Committee Subjective Knee Form: Which Questionnaire Is Most Useful to Monitor Patients With an Anterior Cruciate Ligament Rupture in the Short Term?

Purpose: To evaluate which questionnaire, the Knee Injury and Osteoarthritis Outcome Score (KOOS) or the International Knee Documentation Committee Subjective Knee Form (IKDC subjective), is most useful to evaluate patients with recent anterior cruciate ligament (ACL) ruptures or those within 1 year of an ACL reconstruction. Methods: Patients with recent (0-6 months) ACL ruptures or those with indications for ACL reconstruction were included. All patients completed the questionnaires shortly after trauma or preoperatively and again 1 year later. The KOOS has 5 subscales, each scored separately. The IKDC subjective consists of one total score. The following measurement properties of the KOOS and IKDC subjective were assessed: content validity (n = 45), construct validity (n = 100), test-retest reliability (n = 50), and responsiveness (n = 50). Results: Regarding content validity, 2 KOOS subscales (Pain and Activities of Daily Living) were scored as nonrelevant. Two of the 18 questions on the IKDC subjective were assessed as nonrelevant. Only the KOOS subscale Sport and Recreation Function had acceptable construct validity (79% confirmation of the predefined hypotheses). None of the KOOS subscales had a sufficient score for responsiveness (<75% confirmation of the predefined hypotheses). The IKDC subjective scored acceptable for construct validity (84% confirmation of the predefined hypotheses) and responsiveness (86% confirmation of the predefined hypotheses). All KOOS subscales and the IKDC subjective had a reliability (intraclass correlation coefficient [ICC]) of 0.81 or higher. Conclusions: The IKDC subjective is more useful than the KOOS questionnaire to evaluate both patients with recent ACL ruptures and those in the first year after ACL reconstruction. Level of Evidence: Level III, prognostic validation study.