This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Avascular necrosis and osteochondroses, Subject name: Orthopaedics
[{'content': 'A 45 year old was given steroids after renal transplant. After 2 years he had difficulty in walking and pain in both hips. Which one of the following is most likely cause - \nSelect and explain. \nA. Primary osteoahritis, B. Avascular necrosis, C. Tuberculosis, D. Aluminum toxicity', 'role': 'user'}, {'content': 'Answer: B \nExplanation: High dose coicosteroid & alcohol abuse are the commonest causes of avascular necrosis,the commonest site being femoral head.the mechanism is intravascular thrombosis-hyperlipidemia & fatty degeneration of liver;fat embolism give rise tocapillary endothelial damage,platelet aggregation & thrombosis. reference:Apleys,9th edition,page no104', 'role': 'assistant'}]