In adolescents with hip pain and limp, which condition must be screened, and which radiographic views are recommended?

• A. Slipped capital femoral epiphysis; AP pelvis and frog-leg lateral views
• B. Avascular necrosis; MRI of the hip
• C. Leg length discrepancy; standing full-length X-ray
• D. Septic arthritis; hip ultrasound and X-ray

Answer: (B)

In adolescents with hip pain and a limp, screening for avascular necrosis is crucial because AVN can progress and damage the femoral head if not detected early. MRI of the hip is the best tool for this purpose because it is highly sensitive to early bone marrow changes and can reveal necrotic areas before X-rays show any abnormality. Early MRI findings guide timely management to preserve the joint. While standard radiographs (AP pelvis and frog-leg lateral) are good for initial assessment and for detecting conditions like slipped capital femoral epiphysis, they may appear normal early in AVN, making MRI the more reliable option when AVN is a concern.