A 6-year-old boy presents with a 3-month history of intermittent limping and mild left hip discomfort. Plain radiograph shows increased density of the left femoral head with a subchondral fracture line (crescent sign). Which investigation is most useful for assessing the extent of femoral head involvement and prognosis?
- A MRI of the hip ✓
- B Ultrasound of the hip
- C Plain radiograph (AP and frog lateral)
- D Bone scintigraphy
Correct answer: A. MRI of the hip
Explanation
MRI is the most sensitive modality for assessing the extent of epiphyseal infarction, articular surface congruity, and lateral pillar status in Perthes disease. It detects bone marrow edema and cartilaginous changes before plain radiograph changes evolve. Bone scintigraphy has largely been replaced by MRI. Plain radiographs are used for initial diagnosis and staging but underestimate cartilaginous involvement.
Reference: Rockwood and Wilkins' Fractures in Children, 9th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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