Translation, Cross-Cultural Adaptation and Validation of the 10-Item Spine Functional Index (SFI-10) for Greek Patients with Musculoskeletal Spine Disorders

Background Musculoskeletal spine disorders are a leading cause of disability worldwide. The Spine Functional Index (SFI) is a whole-spine patient-reported outcome measure, and its short form (SFI-10) has demonstrated satisfactory psychometric properties across multiple languages. However, no validated Greek version has been available. Methods This cross-sectional study included 110 adults with chronic, non-specific spinal pain. Participants completed the Greek version of the SFI-10, alongside established measures of pain and health-related quality of life. Internal consistency, test-retest reliability, measurement error, structural validity and convergent validity were calculated. Results The Greek SFI-10 demonstrated acceptable internal consistency (Cronbach’s α = 0.794) and excellent test-retest reliability (ICC _2,1 = 0.955). Measurement error was low (SEM = 0.403; MDC ₉₀  = 0.935), and responsiveness indices indicated adequate sensitivity to change. Factor analyses supported a one-factor structure (EFA eigenvalue = 4.96), with good model fit in CFA (CFI = 1.000; RMSEA = 0.000). Convergent validity was confirmed through significant correlations with NPRS (r = 0.634; p < 0.001), SF-BPI pain interference (r = 0.819; p < 0.001), SF-BPI pain severity (r = 0.628; p < 0.001) and EQ-5D-5L (r = − 0.722; p < 0.001). Conclusion The Greek version of the SFI-10 is a valid and reliable patient-reported outcome measure for assessing whole-spine function in individuals with musculoskeletal spine disorders. Its brevity and ease of use support its application in both clinical practice and research, involving Greek-speaking populations.