{"knowledge_schema": {"broad_category": "Medicine \u2192 Rheumatology \u2192 Joint Disorders", "refinement": "This problem involves diagnosing a joint condition based on clinical presentation, laboratory findings, and imaging results.", "specific_scope": "The focus is on a 68-year-old patient with ankle pain and swelling, with negative X-rays and synovial fluid analysis showing no crystals or infection.", "goal": "Identify the most likely diagnosis based on the provided clinical information and test results."}, "summary": "The clinical scenario describes a 68-year-old patient with persistent ankle pain and swelling, negative X-rays, and synovial fluid analysis that shows no crystals or signs of infection. Given the symptoms and the laboratory findings, the most likely diagnosis is Osteoarthritis, as it is common in older patients and can present with similar symptoms without acute inflammatory changes in the synovial fluid."}