Question:medium
Which of the following is a radiological sign in Perthes disease?
Which of the following is a radiological sign in Perthes disease?
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The necrotic head collapses and drifts out of the acetabulum on imaging.
Updated On: Jun 24, 2026
- Epiphyseal calcification
- Organized calcification
- Lateral subluxation of femoral head
- Restriction of abduction
Show Solution
The Correct Option is C
Solution and Explanation
Step 1: The disorder in question is a childhood osteonecrosis of the capital femoral epiphysis caused by interruption of its blood supply, known eponymously as Perthes disease.
Step 2: When the dead epiphysis collapses and broadens, the femoral head can no longer sit fully inside the socket and drifts outward. On a radiograph this lateral migration of the head is reported as lateral subluxation, a true imaging feature of the disease.
Step 3: Supporting X-ray clues across the stages are a subchondral crescent fracture line, a dense then fragmented epiphysis, joint-space widening, and eventual flattening into coxa plana.
Step 4: Limited abduction belongs to the bedside examination rather than the film, and neither epiphyseal calcification nor organized calcification describes Perthes. Hence the imaging sign is lateral subluxation of the femoral head.
\[\boxed{\text{Lateral subluxation of femoral head}}\]
Step 2: When the dead epiphysis collapses and broadens, the femoral head can no longer sit fully inside the socket and drifts outward. On a radiograph this lateral migration of the head is reported as lateral subluxation, a true imaging feature of the disease.
Step 3: Supporting X-ray clues across the stages are a subchondral crescent fracture line, a dense then fragmented epiphysis, joint-space widening, and eventual flattening into coxa plana.
Step 4: Limited abduction belongs to the bedside examination rather than the film, and neither epiphyseal calcification nor organized calcification describes Perthes. Hence the imaging sign is lateral subluxation of the femoral head.
\[\boxed{\text{Lateral subluxation of femoral head}}\]
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