Question:medium
A 30 year old patient with nephrotic syndrome has been on steroids for 14 years. He has bilateral difficulty in abduction and internal rotation of the hip, and attempting to flex the hip results in abduction. What is the cause?
A 30 year old patient with nephrotic syndrome has been on steroids for 14 years. He has bilateral difficulty in abduction and internal rotation of the hip, and attempting to flex the hip results in abduction. What is the cause?
Show Hint
Long-term steroids are a classic cause of femoral head osteonecrosis.
Updated On: Jul 8, 2026
- Avascular Necrosis of Femur Head
- Septic Arthritis
- Renal Osteodystrophy
- Heterotopic Calcification
Show Solution
The Correct Option is A
Solution and Explanation
Step 1: Start from the drug history.
Steroids taken for 14 years is the loudest clue here. A high cumulative steroid dose is one of the top causes of bone death in the femoral head, working through fat embolism and raised pressure inside the bone that cuts off blood supply.
Step 2: Match the exam findings to the diagnosis.
As the femoral head caves in on its weight bearing surface, the hip loses internal rotation and abduction first. When the patient tries to flex the hip, the joint surfaces no longer glide smoothly, so the leg drifts into abduction instead of flexing straight, the sign described in the question.
Step 3: Test the other choices against the story.
Septic arthritis would show a hot, swollen, acutely painful joint with fever, not a slow bilateral change over years. Renal osteodystrophy affects bone mineral turnover from kidney failure and gives generalised bone pain and deformity, not this specific hip sign, and nothing here says the kidneys have failed. Heterotopic calcification needs a trigger like major trauma or spinal injury, which is not present here.
Step 4: Settle on the diagnosis.
The combination of prolonged steroid use with loss of internal rotation and abduction, plus a positive flexion-abduction sign, points to avascular necrosis of both femoral heads.
\[ \boxed{\text{Avascular Necrosis of Femur Head}} \]
Steroids taken for 14 years is the loudest clue here. A high cumulative steroid dose is one of the top causes of bone death in the femoral head, working through fat embolism and raised pressure inside the bone that cuts off blood supply.
Step 2: Match the exam findings to the diagnosis.
As the femoral head caves in on its weight bearing surface, the hip loses internal rotation and abduction first. When the patient tries to flex the hip, the joint surfaces no longer glide smoothly, so the leg drifts into abduction instead of flexing straight, the sign described in the question.
Step 3: Test the other choices against the story.
Septic arthritis would show a hot, swollen, acutely painful joint with fever, not a slow bilateral change over years. Renal osteodystrophy affects bone mineral turnover from kidney failure and gives generalised bone pain and deformity, not this specific hip sign, and nothing here says the kidneys have failed. Heterotopic calcification needs a trigger like major trauma or spinal injury, which is not present here.
Step 4: Settle on the diagnosis.
The combination of prolonged steroid use with loss of internal rotation and abduction, plus a positive flexion-abduction sign, points to avascular necrosis of both femoral heads.
\[ \boxed{\text{Avascular Necrosis of Femur Head}} \]
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