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': 'A most common cause of bony ankylosis- \nSelect and explain. \nA. Rheumatoid arthritis, B. Pyogenic arthritis, C. Traumatic arthritis, D. Osteoarthritis', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ankylosis\n\nAnkylosis is the fusion of bones in a joint leading to stiffness of the joint.\nAnkylosis may be : -\n\n1) Fibrous ankylosis: - Two articular surfaces are fused by fibrous tissue.\nThe feature are : -\n\nSome movement of joint is possible (though just a jog of movement).\n\n\nMovements may be painless or painful.\nMost common cause is tubercular arthritis.\n\n\n2)\xa0Bony ankylosis: - There is a bony union between two articular surfaces. The features are : -\n\nNo movements possible.\na Joint is painless\nA most common cause is acute suppurative arthritis (septic arthritis).\nSometimes, stiffness may also occur due to extra-articular etiology such as in Bum contracture, myositis ossificans etc. It is called False ankylosis.', 'role': 'assistant'}]