What is the primary diagnostic test for SCFE?

• A. Ultrasound of the hip
• B. MRI of the hip
• C. X-ray of the hip.
• D. CT scan of the pelvis

Answer: (C)

Plain X-ray imaging of the hip is the primary diagnostic test for Slipped Capital Femoral Epiphysis. In adolescents with hip or knee pain and a limp, SCFE slips the femoral head downward and backward at the growth plate, and this is best seen on radiographs of the pelvis with an AP view and a frog-leg lateral view. Look for displacement of the epiphysis relative to the metaphysis, widening of the growth plate, and the Klein line sign (a line along the top of the femoral neck that should intersect the femoral head; if it doesn’t, slip is likely). The frog-leg lateral view is especially helpful to reveal posterior displacement that may be subtle on the AP view.

Ultrasound isn’t diagnostic for SCFE and won’t reliably show the slip. MRI can detect early slips or occult instability when radiographs are inconclusive, but it’s not the first-line test. CT isn’t routinely used for initial diagnosis; it may be reserved for complex anatomy or surgical planning.