Translation, cross-cultural adaptation and validation of the Hamstring Outcome Score (HaOS) in French for surgically treated hamstring injuries

Background: The Hamstring Outcome Score (HaOS) is a patient-reported outcome measure designed to assess function following hamstring injuries. No French version currently exists. Purpose: To translate, culturally adapt, and validate the HaOS in French (HaOS-Fr) in a cohort of patients undergoing surgical repair for proximal hamstring avulsion injuries (PHAI). Methods: A prospective study was conducted between July 2020 and July 2022 in a sport surgery center. Forty-eight French-speaking patients who had undergone surgical treatment for PHAI were included at 6 months postoperatively. The HaOS questionnaire was translated and culturally adapted using international guidelines, including forward and backward translation, expert committee review, and pretesting. Psychometric evaluation was performed according to COSMIN criteria. Construct validity was assessed by comparing HaOS with the UCLA activity scale, Tegner scale, Lysholm score, and subjective hip value. Discriminant validity was tested by comparing injured vs. uninjured sides. Test-retest reliability was evaluated in 10 patients. Return to sport (RTS) was also documented. Results: The HaOS-Fr showed excellent internal consistency (Cronbach’s α = 0.93) and excellent test-retest reliability (ICC = 0.90, 95% CI [0.86–0.94]). Construct validity showed strong correlation with Lysholm (r = 0.801), moderate with UCLA (r = 0.478), and weak with subjective hip value (r = 0.297); correlation with Tegner was not significant (p = 0.066). HaOS scores were significantly higher in uninjured limbs (p < 0.001). Among 48 patients, 64.6% returned to sport, and 64.5% of them at the same level. ROC analysis for RTS prediction showed AUC = 0.631 (p = 0.14). No floor or ceiling effects were detected. Conclusion: The HaOS-Fr is a valid, reliable, and feasible tool for evaluating outcomes in French-speaking patients after surgical treatment for PHAI. It enables functional assessment and contributes to reinjury risk stratification.