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.