A 10-year-old overweight boy with hip pain and limping has radiographic disruption of Klein's line. What is your initial impression?

A 10-year-old overweight boy with hip pain and limping has radiographic disruption of Klein's line. What is your initial impression?

• A. Slipped Capital Femoral Epiphysis
• B. Subcapital Femoral Fracture
• C. Legg-Calvé-Perthes Disease
• D. Avascular Necrosis

Answer: (A)

Disruption of Klein's line points to slipped capital femoral epiphysis. Klein's line runs along the superior border of the femoral neck on hip radiographs; in a normal hip, the superior femoral head lies just under or crosses this line. When the capital femoral epiphysis slips downward and posteriorly through the growth plate, the head no longer aligns with that line—so the line appears disrupted. This radiographic sign, combined with the patient being an overweight preteen with hip pain and a limp, makes SCFE the most likely diagnosis. Legg-Calvé-Perthes disease would typically show flattening or fragmentation of the femoral head in a younger child and evolves differently on imaging. A subcapital femoral fracture would present with an acute fracture line and displacement. Avascular necrosis is a potential complication or later finding, not the initial radiographic clue.

Disruption of Klein's line points to slipped capital femoral epiphysis. Klein's line runs along the superior border of the femoral neck on hip radiographs; in a normal hip, the superior femoral head lies just under or crosses this line. When the capital femoral epiphysis slips downward and posteriorly through the growth plate, the head no longer aligns with that line—so the line appears disrupted. This radiographic sign, combined with the patient being an overweight preteen with hip pain and a limp, makes SCFE the most likely diagnosis.

Legg-Calvé-Perthes disease would typically show flattening or fragmentation of the femoral head in a younger child and evolves differently on imaging. A subcapital femoral fracture would present with an acute fracture line and displacement. Avascular necrosis is a potential complication or later finding, not the initial radiographic clue.