A 71-year-old man comes to the clinic reporting bilateral knee pain that has progressively worsened over six months. He describes a deep aching that is worst after prolonged standing and improves with rest. He has tried acetaminophen at maximum doses without adequate relief. His medical history is notable for a duodenal ulcer diagnosed three years ago, treated successfully with H. pylori eradication; he has been symptom-free since. He also has well-controlled hypertension managed with amlodipine and mild hyperlipidemia. He has no history of myocardial infarction, stroke, heart failure, or chronic kidney disease, and he does not use anticoagulants or corticosteroids. Examination reveals bilateral knee crepitus and mild joint-line tenderness. Knee radiographs show symmetric joint space narrowing with marginal osteophyte formation bilaterally. Creatinine is 0.9 mg/dL and blood pressure is 128/76 mmHg.
Which of the following is the most appropriate pharmacotherapy for this patient's knee pain?