Avascular necrosis of the femoral head in children under the age of three.

Avascular necrosis of the femoral head in very young children may be secondary to traumatic, septic, metabolic, iatrogenetic causes. In most cases, however, the etiology is unclear and generally described in the orthopedic literature in ambiguous terms. Radiologically, the femoral head ossification center may be condensed, deformed or fragmented. Etiologically, the cases placed in 3 groups: idiopathic osteochondritis of the femoral head or early discovered Perthes' disease; dysplasia capiti femoris or a malformation belonging to the group of spondylo epiphyseal dysplasia; deformation of the femoral head through malposition such as C.D.H. Though it is a typical complication of the treatment of dislocated hips, avascular necrosis may occur in association with untreated and even mild subluxation.