Background: Western Ontario and McMaster Universities (WOMAC) Osteoarthritis index is a multidimensional self-reported disease-specific questionnaire that assesses pain, stiffness and physical disability in patients with Osteoarthritis (OA) of the knee joint. Purpose: The aim of the study was to assess validity and reliability of the Arabic Version of WOMAC Osteoarthritis index in Egyptians with knee OA. Methods: The Arabic version of WOMAC Osteoarthritis Index was administered to fifty Egyptian knee OA. Range of motion (ROM) of knee flexion and radiographic severity were assessed for all patients by digital goniometer and X-Ray, respectively. Validity was assessed by relating the WOMAC to knee flexion range of motion and radiographic severity using spearman correlation coefficient. Besides, internal consistency and reliability were evaluated by Cronbach’s alpha and intra-class correlation coefficients (ICC), respectively.

Results: Arabic Version of WOMAC Osteoarthritis Index showed weak correlation with knee flexion range of motion (rho=-0.36, P=0.037) and little non-significant correlation with radiographic severity. Cronbach’s alphas were 0.74–0.82. Test–retest reliability was 0.58–0.693.

Conclusion: Arabic Version of WOMAC Osteoarthritis Index is a reliable but less valid index for use in Egyptian patients with knee OA.