Validation of the Spanish Version of the Forgotten Joint Score in Total Hip Arthroplasty

Objective: To translate, culturally adapt, and validate the Forgotten Joint Score (FJS) into Spanish for use in patients who have undergone total hip arthroplasty (THA). Methods: The FJS was translated and culturally adapted following international guidelines. A cross-sectional validation study was conducted in two Chilean institutions. Patients who underwent THA for primary osteoarthritis between 2018 and 2019 were recruited. The Spanish FJS and the validated Spanish version of the Oxford Hip Score (OHS) were administered to assess reliability and validity. Internal consistency was measured using Cronbach’s alpha. Test-retest reliability was assessed using the intraclass correlation coefficient (ICC), Lin’s concordance correlation coefficient (CCC), and the Bradley-Blackwood test. Construct validity was evaluated through Spearman’s correlation with the OHS. Results: A total of 241 patients completed the first round, and 184 completed the second round. The Spanish FJS showed excellent internal consistency (Cronbach’s alpha = 0.967 and 0.977 for the first and second rounds, respectively). Test-retest reliability was strong (ICC = 0.84; CCC = 0.84), with no significant difference between rounds (p = 0.52). Construct validity was supported by a moderate negative correlation with the OHS (rho = -0.64 and -0.65 for rounds one and two, respectively). Ceiling and floor effects were low across both instruments. Conclusion: The Spanish version of the FJS is a valid and reliable patientreported outcome measure for assessing satisfaction and joint awareness following THA. Its inclusion in clinical practice and national registries is strongly recommended for Spanish-speaking populations.