Cross-cultural adaptation, reliability and validity of the European Portuguese version of the Lower Extremity Functional Scale

PURPOSE: To translate and culturally adapt the LEFS into European Portuguese and evaluate its measurement properties in adults with lower limb musculoskeletal disorders. METHODS: The LEFS was translated and adapted following international guidelines. A total of 105 participants completed the LEFS, SF-36 and baseline form; 80 repeated the LEFS after 48-72 h. Structural validity was assessed by confirmatory factor analysis. Internal consistency, test-retest reliability, measurement error, floor/ceiling effects and construct validity through a priori hypothesis testing were evaluated. RESULTS: Cross-cultural adaptation supported conceptual, semantic and operational equivalence. Structural validity was mixed: one-factor and correlated two-factor models met the SRMR criterion, whereas other fit indices were suboptimal. Internal consistency was adequate (α = .984), and test-retest reliability was good (ICC = .970; weighted kappa = .769-.956). SEM was 4.17 and SDC was 11.56. Floor and ceiling effects were minimal (2.9% and 0%). Construct validity hypotheses were confirmed, with strongest correlations between LEFS and SF-36 Physical Functioning (ρ = .916 total; .555 acute; .812 chronic). CONCLUSION: The European Portuguese LEFS showed adequate internal consistency, good test-retest reliability, acceptable measurement error and evidence supporting construct validity; structural validity should be interpreted cautiously.