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: Surgery
[{'content': 'Avascular necrosis of head of femur occurs commonly at : \nSelect and explain. \nA. Subcapital region, B. Transcervical region, C. Subchondral region, D. Trochanteric region', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Avascular necrosis is common with fractures to the subcapital region. Subcapital fractures damage the ascending vessels, thereby causing avascular necrosis and nonunion. Subcapital is the most common location for a femoral fracture. Ref: Srinivasan R.C., Tolhurst S., Vanderhave K.L. (2010). Chapter 40. Ohopedic Surgery. In G.M. Dohey (Ed), CURRENT Diagnosis & Treatment: Surgery, 13e.', 'role': 'assistant'}]