Role of Methotrexate in Ultrasound Proven Synovitis in Primary Knee OA

Inclusion Criteria: * Men and women aged between 40 to 70 years * Patients fulfilling American College of Rheumatology (ACR) clinical and radiological criteria for knee OA. (knee pain + at least 3 of 5 that not including "no palpable warmth") * Knee pain on most days for at least 6 months, with a pain VAS of at least 40mm * Radiological grading of OA with Kallgren-Lawrence grade of 2 to 3 * Patients with the presence of knee synovitis in Musculoskeletal ultrasound Exclusion Criteria: * Any known inflammatory arthritis * BMI \>= 40 kg/m2 * Abnormal renal (e.g. abnormal renal function Creatinine clearance \<35 ml) hepatic (including active hepatitis B, hepatitis C, abnormal liver function), hematological (e.g. white cell count \< 4 × 109/L, platelets \<100 ×109/L, or hemoglobin \< 9 g/dL), function * Use of intra-articular, intramuscular or oral corticosteroids in previous 4 weeks * History knee joint surgery, Charcot joint * Severe valgus knee deformity (angle of genu valgum \> 30°) * Use of any disease modifying agents (e.g. hydroxychloroquine or sulfasalazine) in previous 3 months * Allergic to MTX * Pregnant or lactating women