The Femoral Head Notch

The femoral head notch is a defect at the vertex of the proximal femoral ossification center in mid-childhood. This may be seen as a normal variant and can be mistaken for early or "abortive" Legg-Perthes disease.

It can be differentiated from Legg-Perthes by noting the absence of associated changes of ischemic necrosis: diminished size and sclerosis of the ossification center, widening of the distance between the medial acetabular wall and the ossification center, and a fracture line.

Defects seen in intermediate stage Legg-Perthes disease may mimic the femoral head notch, but are located lateral to the vertex, not centrally.

Finally, abnormalities in Legg-Perthes disease are characteristically more obvious and better defined on the lateral view, while the femoral head notch is actually less defined on this view.

References

Ozonoff MB, Ziter FM Jr. The femoral head notch. Skeletal Radiol. 1987;16(1):19-22.