A 62-year-old woman from Delhi presents with a 3-year history of progressive pain and stiffness in both knees, worse in the morning and after prolonged sitting. She has a BMI of 28 kg/m². On examination, there is crepitus on knee flexion, mild effusion, and bony enlargement of the joint margins. X-ray of both knees shows joint space narrowing, osteophytes, and subchondral sclerosis. She has tried NSAIDs with partial relief. Which of the following is the most appropriate next step in management?