Translation, Validation, and Cultural Adaptation of the Greek Versions of the Lysholm Knee Score and Tegner Activity Scale in Patients With Anterior Cruciate Ligament Injury

Background: The Lysholm score and the Tegner Activity Scale (TAS) are two knee-specific patient-reported outcome measures with widespread clinical and research use in patients after anterior cruciate ligament (ACL) injury. However, there is a lack of previously validated Greek-language patient-reported outcome measures for ACL-injured patients. The aim was to translate, cross-culturally adapt, and evaluate the psychometric properties of the Lysholm score and TAS in Greek for patients with ACL injury. Methods: Translation and cross-cultural adaptation of Lysholm and TAS questionnaires into Greek, along with a full psychometric assessment of both questionnaires, were conducted using international guidelines. Convergent validity was assessed by determining their correlation to the Greek International Knee Documentation Committee - Subjective Knee Form (IKDC-SKF) and 36-Item Short Form Health Survey (SF-36) physical functioning subscale using Pearson’s correlation coefficient (r). Internal consistency of the Greek Lysholm score was determined using the Cronbach’s alpha coefficient (α). Test-retest reliability was examined in 40 patients drawn from the total study sample with the intraclass correlation coefficient (ICC) comparing the Greek Lysholm score and TAS values at baseline and around seven days later. Results: The questionnaires were distributed to 98 adult patients with ACL injury (mean age: 25.5 years; 77 males). Forward-backward translations and cultural adaptation were smooth and consistent. Factor and Rasch analyses confirmed the unidimensional proposed factor structure of the Lysholm score. Both Lysholm and TAS showed strong correlation with the IKDC-SKF (r = 0.800 and r = 0.662, respectively) and the SF-36 physical functioning subscale (r = 0.713 and r = 0.597, respectively). There were no floor and ceiling effects. The Greek Lysholm score showed excellent internal consistency (α = 0.852), whilst both Lysholm and TAS had excellent test-retest reliability (ICC: 0.995 and 1, respectively). Conclusions: The Greek-translated versions of the Lysholm score and TAS for patients with ACL injury are conceptually equivalent to the original versions with excellent cross-sectional validity and reliability. They are valid and reliable outcome measures for assessment of knee function and activity level in patients with ACL injury in Greece, and their use is recommended in clinical practice and research for ACL-injured patients in Greece.