This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General, Subject name: Orthopaedics
[{'content': 'Pathognomic sign of traumatic fracture is \nSelect and explain. \nA. Tenderness, B. Swelling, C. Crepitus, D. Bruising', 'role': 'user'}, {'content': "Answer: C \nExplanation: C. i.e. (Crepitus) (545 - Apley 8th)* Crepitus or abnormal movement is pathognomic to traumatic fracture.* Posterior - interosseous nerve invovemet in Monteggia fracture dislocation* Peroneal nerve involvement in knee dislocationMotor cyclists fractures - The motorcyclists sustains a ring fracture and the pillion rider an atlanto - occipital avulsion with dural tear Anteroflexion without impact on the occiput seems to be a rare casual mechanism of the 'ring' fracture.", 'role': 'assistant'}]