Legg-Calve-Perthes disease is a complex pediatric hip disorder with many uncertainties. Various theories on its etiology have been proposed but none have been validated conclusively. Through experimental studies, however, some insight into the pathogenesis of a femoral head deformity after ischemic necrosis has been gained. These studies reveal that mechanical and biological factors contribute to the development of the femoral head deformity. Better understanding of the pathobiology of Legg-Calve-Perthes disease will lead to the development of more effective treatments, which are able to specifically target the pathogenic processes.