This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Orthopaedics
A 60-year-old man with diabetes mellitus presents with painless, swollen right ankle joint. Radiographs of the ankle show destroyed joint with a large number of loose bodies. The most probable diagnosis is - 
Select and explain. 
A. Charcot's joint, B. Clutton's joint, C. Osteoarthritis, D. Rheumatoid arthritis
A: Charcot's joint
Answer: A: Charcot's joint 
Explanation: Painless swollen ankle, destroyed joint and multiple loose bodies in a diabetic patient suggest the diagnosis of Charcot’s joint (neuropathic joint).
Joint destruction without pain is characteristic of Charcot’s joint.