Cross-cultural adaptation and validation of a revised Italian Anterior Knee pain Scale version

BACKGROUND: The study aimed to validate a revised Italian version of the Anterior Knee pain Scale (AKpS) by addressing shortcomings in previous adaptations and following the COSMIN guidelines to ensure robust psychometric evaluation. METHODS: One hundred thirty patients with anterior knee pain symptoms were recruited, with 65 undergoing a retest after 7 days to assess the scale's reliability. Structural validity was assessed through confirmatory factor analysis (CFA) to evaluate the scale's dimensionality. Internal consistency was measured using Cronbach's alpha, while test-retest reliability was assessed using the intraclass correlation coefficient (ICC). Measurement error was evaluated using the standard error of measurement (SEM) and the smallest detectable change (SDC). Construct validity was examined by correlating the AKpS with other established scales, including the Knee Injury and Osteoarthritis Outcome Score, Internal Knee Documentation Committee, Victorian Institute of Sport Assessment-patella, Short-Form 36 Health Survey, and the Visual Analogue Scale. RESULTS: The CFA supported a three-factor model encompassing pain intensity and interference, functional limitations in daily activities, and knee structural and functional issues. The scale demonstrated good internal consistency (Cronbach's alpha=0.79) and excellent test-retest reliability (ICC=0.91), with low measurement error (SEM<5%). Construct validity was confirmed through moderate-to-strong correlations with related scales, particularly in domains related to pain intensity, symptoms, and daily functioning. CONCLUSIONS: The newly validated scale, demonstrating strong psychometric properties, meets international standards for clinical assessment tools, making it a reliable and effective instrument for assessing anterior knee pain in the Italian context.