Background: The Merle d'Aubigné-Postel (MDP) score is a widely used patient-reported outcome measure (PROM) for assessing hip function, encompassing domains of pain, walking ability, and mobility. Despite its global application, a validated Persian version has been unavailable. This study aimed to translate, culturally adapt, and evaluate the reliability and validity of the Persian MDP score for use in Persian-speaking patients undergoing total hip arthroplasty (THA).

Methods: Following Guillemin's guidelines, the MDP score was translated into Persian through forward and backward translations, expert review, and pretesting with 20 patients to ensure cultural relevance and clarity. The adapted tool was then validated in 103 Persian-speaking patients post-THA with a minimum follow-up of one year, assessing internal consistency (Cronbach's alpha), test-retest reliability (intraclass correlation coefficient [ICC]), construct validity (correlation with Harris Hip Score [HHS]), criterion validity (correlation with HHS and Western Ontario and McMaster Universities Osteoarthritis Index [WOMAC]), and content validity (floor and ceiling effects). Inter-rater reliability was assessed among three orthopedic residents for the mobility component.

Results: The Persian MDP demonstrated high internal consistency (α = 0.74) and excellent test-retest reliability (ICC = 0.95; 95% CI: 0.91-0.98). Inter-rater reliability for the mobility component was excellent (ICC = 0.89; 95% CI: 0.82-0.94). Construct validity was supported by strong domain-specific correlations (e.g., MDP pain vs. HHS pain: r = 0.73; 95% CI: 0.62-0.81). Criterion validity was confirmed by robust correlations with WOMAC (r = 0.745; 95% CI: 0.65-0.82) and HHS (r = 0.753; 95% CI: 0.66-0.83). Content validity showed a minimal floor effect (0%) and acceptable ceiling effect (14.5%).

Conclusion: The Persian MDP score is a valid and reliable tool for assessing outcomes after THA in Persian speakers. Its simplicity and strong psychometric properties support its use in both clinical practice and research. However, the ceiling effect warrants consideration in populations with excellent outcomes.