This is a randomized, double-blind study to compare the efficacy and safety of LAYLA tablet and CENATONE tablet in the treatment of osteoarthritis of the knee.

Inclusion Criteria:

• Patients ≥40 and ≤80 years of age
• Radiographic evidence of grade 1,2 or 3 osteoarthritis based on the Kellgren & Lawrence radiographic entry criteria
• Stable osteoarthritis during 3 months
• Score of 100mm Pain VAS ≤ 80mm at screening
• Score of 100mm Pain VAS ≥ 40mm at baseline
• Written consent form voluntarily

Exclusion Criteria:

• Disease of spine or other Lower limb joints that could affect fo evaluate the efficacy
• History of surgery or arthroscopy of the study joint within 6 months
• Trauma of study joint within 12 months
• Medication of constantly(more than 1 week) corticosteroid by oral within 3 months
• Diagnosed with psychical disorder, and taking medication
• Medication of intra-articular injection within 3 months
• Uncontrollable Hypertension patients at screening test
• History of upper gastrointestinal ulceration within 6 months, History of upper gastrointestinal bleeding within 12 months
• History of lower gastrointestinal bleeding within 12 months
• History of coronary artery bypass, systemic lupus erythematosus or mixed connective tissue disease
• Serum creatinine, ALT, AST, total bilirubin over ULN X 2.0 at screening test
• History of hypersensitivity of LAYLA, CENATONE or NSAIDs
• Participation in another clinical trials within 4 weeks
• Medication of constantly (more than 1 week) narcotic analgesics within 3 months
• Not consent about using effectual contraception method during trial
• Pregnant or lactating woman
• History of malignant tumor within 5 years
• Investigator's judgment