Avascular necrosis of the femoral head in children.

Two types of AVN occur in childhood. The first is the idiopathic type best characterized by Legg-Calvé-Perthes' disease associated with repeated infarctions that slow the healing process. The second is the traumatic type caused by a direct insult to the blood supply of the developing femoral head. Both can result in profound growth disturbances of the proximal femur and early degenerative changes. They may have little effect on hip function or appearance. The variables affecting these outcomes are the age of the child, the degree of femoral head involvement, the presence of at-risk signs, the ability of the acetabulum to contain the healing head, and whether or not the growth plate closes as a result of the AVN. Bone scans and magnetic resonance imaging offer some potential for improved accuracy in diagnosis and prediction. The recommendation treatment for AVN in children is to treat the synovitis whenever it occurs or recurs. Abduction bracing should be used for the first six months in most young children with idiopathic AVN of the Legg-Calvé-Perthes' type. Protected weightbearing with crutches should suffice for the early phases of traumatic AVN. Within six months, one should be able to determine the classification and whether to continue the treatment being used or to change to another form of treatment. Petrie casts are used rarely but can be very useful in certain patients. Prolonged crutch use may help to prevent collapse while relieving symptoms in the older child.(ABSTRACT TRUNCATED AT 250 WORDS)