Distal irregularities of the femur simulating malignancy.

Roentgenograms of the knees, externally rotated, in 100 children were reviewed in evaluation of the irregularity seen on the posteromedial aspect of the distal femurs. Dissection studies of the soft tissue and osseous structures were carried out in order to determine the etiology of this irregularity. It is more commonly seen in boys and on the left side and may be mistaken for malignancy.This apparent break in the cortex, with irregularity and occasional diminutive spicule formation, is a normal finding and due to the medial supracondylar ridge. An aponeurotic sheath from the extensor tendon of the adductor magnus muscle attaches along the medial supracondylar ridge, and with muscle stress and growth causes the development of this ridge. The development of the adductor tubercle is due to the attachment of the extensor tendon of the adductor magnus.The medial supracondylar ridge is not usually seen in the preschool age and is most commonly identified in oblique or lateral projections of the knee in the 10...