Cross‑cultural adaptation and validation of the Persian version of the new Knee Society Knee Scoring System (KSS)

Abstract

Abstract Background The new Knee Society Knee Scoring System (KSS) has been widely used to assess the symptoms, satisfaction, expectations, and physical activities of patients who undergo total knee arthroplasty (TKA). KSS has been translated and validated into many languages but not Persian. The aim of this study was to translate and evaluate the validity and reliability of the Persian version of the new KSS. Methods The Persian version of the new KSS was translated and culturally adapted according to international guidelines, including translation, back-translation, pre-testing, and expert committee review. A total of 142 patients scheduled to undergo TKA were included in this study and were asked to complete the Persian-KSS, Oxford Knee Score (OKS), and the Visual Analogue Scale (VAS) index both two weeks before the surgery and 6 months after the surgery. Face, content, and construct validity were evaluated to assess the validity of Persian-KSS. Results The Persian-KSS was comprehensive, indicating that the Persian version of KSS was clear and easy to understand for Persian-speaking patients undergoing TKA. The reliability of the Persian-KSS, assessed by Cronbach’s alpha, was 0.894 and 0.800 for the pre- and post-operative stages, respectively. The intraclass correlation coefficient (ICC) assessed the test–retest reliability, which was 0.766 and 0.796 for the pre- and post-operative stages, respectively. The construct validity analysis of Persian-KSS demonstrated a statistically significant correlation between Persian-KSS and the OKS (r = − 0.935, p-value = 0.000 for the pre-operative stage, and r = − 0.809, p-value = 0.000 for the post-operative stage) and VAS index (r = − 0.401, p-value = 0.001 for the pre-operative stage and r = − 0.259, p-value = 0.029 for the post-operative stage). Conclusion The Persian-KSS, developed after the translation and cross-cultural adaptation process, was proven to be a reliable and valid assessment measure for those who undergo TKA.