Osteoarthritis (OA) is a common degenerative disease associated with functional impairments, activity limitations, participation restrictions, as well as poor quality life. Therefore, the comprehensive assessment is important to determine how complex problems affect patients with OA. The first aim of this study was to link and allocate items of The Western Ontario and McMaster Universities (WOMAC) OA index with ICF Comprehensive Core Set for osteoarthritis. The second aim was to examine the relationship between the quality of life and each ICF component's scores determined based on clinical data of WOMAC in OA.

Inclusion Criteria:

• diagnosed with OA according to American College of Rheumatology clinical criteria for OA of the knee or hip;[14,15]
• being in the age range 18-65; and
• absence of other diseases affecting functions and daily life (orthopedic, neurological, cardiovascular, metabolic disease and lung pathology).

Exclusion Criteria:

• comorbidity affecting lower extremity and functions (patellofemoral pain syndrome, rheumatoid arthritis, ligament tear, meniscus);
• previous lower extremity surgery;
• Intra-articular steroid or hyaluronic acid injection in the last three months
• cognitive impairments;
• pregnancy; and
• illiteracy.

Eighty-seven patients with OA were included in this study, who met inclusion criteria and were diagnosed with OA by the same rheumatologist according to the American College of Rheumatology Clinical Classification Criteria for OA.