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
[{'content': 'Not true about synovial chondromatosis \nSelect and explain. \nA. Snow storm appearance of joint, B. Most common cause of loose bodies in joint, C. Most common in knee joint, D. Trauma can lead to synovial chondromatosis', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Most common cause of loose bodies is osteoarthritis.', 'role': 'assistant'}]