Abstract
BACKGROUND: The Lysholm knee score and Tegner activity scale are frequently used patient-reported outcome measures in patients with anterior cruciate ligament (ACL) injuries because of their excellent psychometric properties. These questionnaires were originally developed in the English language. PURPOSE: To translate and cross-culturally adapt these measures into the Indonesian language and study their validity and reliability so that they can be used in the Indonesian-speaking population with ACL injuries. STUDY DESIGN: Cohort study (diagnosis/symptom prevalence); Level of evidence, 2. METHODS: After a forward-backward translation procedure and cross-cultural adaptation, validity and reliability were investigated. A total of 253 patients with an ACL injury were sent 4 questionnaires (36-Item Short Form Health Survey, Kujala anterior knee pain scale, Indonesian Lysholm knee score [I-LK], and Indonesian Tegner activity scale [I-TS]). The responses of those patients were analyzed. Following COSMIN guidelines, construct validity, test-retest reliability, internal consistency, floor and ceiling effects, and measurement errors were determined. The Bland-Altman method was used to explore absolute agreement. RESULTS: A total of 106 patients (42% response rate) were included in this study. Construct validity was considered to be good, as more than 75% of the predefined hypotheses on correlations between the I-LK, I-TS, and other measures were confirmed. Reliability proved excellent, with a high test-retest correlation for both questionnaires (intraclass correlation coefficient = 0.99). Bland-Altman analysis showed no systematic bias between testing and retesting. The internal consistency of the I-LK was good (Cronbach alpha = 0.73). For the I-LK and I-TS, floor and ceiling effects were less than 15% (floor: 0% and 4.7%, respectively; ceiling: 12.3% and 3.8%, respectively); the standard error of measurement was 1.8 and 0.9, respectively; the minimal detectable change at the individual level was 5.1 and 0.6, respectively; and the minimal detectable change at the group level was 2.4 and 0.5, respectively. CONCLUSION: Both the I-LK and I-TS appear to be good evaluation tools for Indonesian-speaking patients with an ACL injury.