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
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 - 
Select and explain. 
A. Primary osteoarthritis, B. Avascular necrosis, C. Tuberculosis, D. Aluminum toxicity
B: Avascular necrosis
Answer: B: Avascular necrosis 
Explanation: This patient has : -

History of steroids intake
Pain in both hip
Difficulty in walking


The diagnosis is AVN of the hip.
In 50% of idiopathic cases and 80% of steroid-induced AVN are bilateral.

About other options

Tuberculosis of hip is usually unilateral.
Primary osteoarthritis of hip does not occur at 45 years and has nothing to do with steroid intake.
Aluminium toxicity does not cause bilateral hip pain.