Radiological study of severe proximal femoral focal deficiency.

Twenty-two hips in 20 children, all classified as Amstutz type 3 proximal femoral focal deficiency, were studied by means of plain radiographs, arthrograms (30), ultrasound examination (six), computed tomography (CT) scans (including five arthrographies with CT) and magnetic resonance imaging (MRI; nine). These investigations demonstrated that in 15 hips, the superior femoral epiphysis was mobile in the acetabulum, whereas in six others, it was fixed and fused to the acetabulum. In one case, it was impossible to prove whether the epiphysis was mobile or fixed. The key radiologic and other image features that allow these conclusions to be drawn are described. The therapeutic implications are important, as it would be pointless or harmful to attempt to consolidate the femoral neck or put it into valgus when the epiphysis is spontaneously fixed to the acetabulum.