Radiographic Findings in Slipped Capital Femoral Epiphysis

Plain Radiography
Plain radiography in anteroposterior and lateral views is the primary and often the only imaging study needed to evaluate a slipped epiphysis. Common radiographic findings include widening and irregularity of the physis, a decrease in epiphyseal height in the center of the acetabulum, a crescent-shaped area of increased density in the proximal portion of the femoral neck, and the “blanch sign of Steel” corresponding to the double density created from the anteriorly displaced femoral neck overlying the femoral head.

In an unaffected patient, the Klein line, a straight line drawn along the superior cortex of the femoral neck on anteroposterior radiograph, intersects the lateral capital epiphysis. As progressive displacement of the epiphysis occurs in SCFE, the amount of the Klein line that intersects the epiphysis decreases, compared with the uninvolved hip, and eventually the line fully misses intersection with the proximal femoral epiphysis . A true lateral (cross-table lateral) radiographic view of the hip better defines the extent of posterior displacement of the femoral epiphysis.

Computed Tomography.
CT can be used to confirm epiphyseal displacement and accurately measure the amount of displacement in patients with symptoms suggestive of an SCFE but without documentation on plain radiographs.

Technetium 99M Bone Scan.Bone scanning will show increased uptake in the capital femoral physis of an involved hip, decreased uptake in the presence of osteonecrosis, and increased uptake in the joint space in the presence of chondrolysis.