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 neutral triangle is seen radiologically in- \nSelect and explain. \nA. Neck femur, B. Proximal humerus, C. Calcaneum, D. Talus', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Neutral triangle of the calcaneum\n\nWithin the trabeculae of calcaneus lies the neutral triangle, an area directly below the distal edge of a posterior facet.\nThe base of the triangle is the weakest, most vulnerable portion of the calcaneum.\nAxial impaction of the talus into the calcaneum results in a vertical fracture through the neutral triangle, and it represents the primary fracture line.', 'role': 'assistant'}]