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': 'The joint commonly involved in sphffitic arthritis is- \nSelect and explain. \nA. Hip, B. Shoulder, C. Wrist, D. Knee', 'role': 'user'}, {'content': "Answer: D \nExplanation: Syphilic arthritis\n\nSyphilic arthritis may be seen in congenital or acquired syphilis.\n\nCongenital syphilis\n\nThe joint may be affected early or late : -\n\n\nEarly congenital syphilis : - Osteochondritis in juxta-epiphyseal region results in breakdown of the bone and cartilage.\nLate congenital syphilis : - Painless synovitis at puberty is called clutton's joint. Most common site is knee followed by elbow, and often is bilateral.\n\nAcquired syphilis\n\nJoint may be involved in the secondary or tertiary stage.\n\n\nSecondary stage : - Transient polyarthritis.\nTertiary stage : - Gummatous polyarthritis, Chorcot's (neuropathic) joint.", 'role': 'assistant'}]