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 psoriatic arthritis \nSelect and explain. \nA. CASPER Criteria, B. Involves DIP, C. Pencil in cup deformity, D. Bamboo sign', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]