Double-Blind, Double Dummy, Randomized Comparison Study to Evaluate the Efficacy and Safety of Valdecoxib 10 mg Once Daily and Naproxen 500 mg Twice Daily in Treating the Signs and Symptoms of Osteoarthritis of the Knee

Inclusion Criteria: * Korean outpatients with symptomatic radiologic evidence of OA of the knee (diagnosed according to the modified American College Rheumatology criteria) * Patient's Assessment of Arthritis Pain measurement of at least 40 mm on VAS * Patients had not received any NSAIDs or analgesics within 2 days (within 4 days for subjects taking oxaprozin, piroxicam or full dose aspirin) prior to the Baseline Visit Exclusion Criteria: * Diagnosis of inflammatory arthritis, gout, pseudogout, Paget's disease, or any chronic pain syndrome that, in the Investigator's opinion, would interfere with the assessment of the Index Knee * Symptomatic anserine bursitis or acute joint trauma of the Index Knee * Arthroscopy performed on the Index Knee within the past 12 months * Complete loss of articular cartilage of the Index Knee * Administration of oral, or intramuscular, intravenous, or soft tissue injections of corticosterosteroids within 4 weeks prior to screening visit * Administration of intra-articular injection of corticosteroids or hyaluronic acid preparation in the Index Knee within 3 months or 6 months, respectively