Legg-Calvé-Perthes Disease
Perthes disease is a condition of unknown etiology in which the vascular supply of the developing femoral head is temporarily interrupted, causing necrosis and collapse of the bony femoral head, followed by spontaneous revascularization and healing of the necrotic bone. It was independently described by four different authors (Legg, Calvé, Perthes, and Waldenstrom) in 1909 and 1910. They identified the condition as an affliction of the hip distinct from trauma and infection. The term "coxa plana" was applied to the characteristic flattening of the femoral head seen in Perthes disease. It was not until 10 years later that the actual pathology of avascular necrotic bone was described. EPIDEMIOLOGY The condition has its onset in children ranging in age from 2 to 12 years, with the majority of patients presenting between the ages of 4 and 8 years. Boys are affected four times more frequently than girls, and the condition is bilateral in approximately 15% of affected children. Certain constitutional factors are frequently found in children with Perthes disease. Skeletal age is delayed in nearly 90% of children affected with it. Affected boys have been found to be an average of 1 in shorter and affected girls 3 in shorter in height than their unaffected peers. Birth weight of affected children is frequently lower than average.