Cross-cultural adaptation, validity and reliability of the Arabic version of the Forgotten Joint Score for knee arthroplasty

Purpose To evaluate the validity and reliability of the Arabic version of this questionnaire in Arabic patients who underwent total knee arthroplasty (TKA). Methods The Arabic version of the English FJS (Ar-FJS) was modified according to cross-cultural adaptation best practices. The study included 111 patients who underwent TKA 1–5 years ago and completed the Ar-FJS. The reduced Western Ontario and McMaster Universities Osteoarthritis Index (rWOMAC) and 36-Item Short Form (SF-36) were used to assess the construct validity of the study. Fifty-two individuals took the Ar-FJS test twice to evaluate the test–retest reliability. Results The reliability of the Ar-FJS demonstrated a Cronbach's α value of 0.940 and an intraclass correlation coefficient of 0.951. The ceiling effect of the Ar-FJS was 5.4% ( n = 6), whereas the floor effect was 1.8% ( n = 2). Additionally, the Ar-FJS showed correlation coefficients of 0.753 and 0.992 for the rWOMAC and SF-36, respectively. Conclusion The Ar-FJS-12 demonstrated excellent internal consistency, repeatability, construct validity, and content validity and can be recommended for patients in Arabic-speaking communities who have undergone knee arthroplasty.