Legg-Calvé-Perthes disease is a juvenile form of idiopathic osteonecrosis of the femoral head that can lead to permanent femoral head deformity and premature osteoarthritis.According to two recent multicenter, prospective cohort studies, current nonoperative and operative treatments have modest success rates of producing a good outcome with a spherical femoral head in older children with Legg-Calvé-Perthes disease.Experimental studies have revealed that the immature femoral head is mechanically weakened following ischemic necrosis.Increased bone resorption and delayed new bone formation, in combination with continued mechanical loading of the hip, contribute to the pathogenesis of the femoral head deformity.Biological treatment strategies to improve the healing process by decreasing bone resorption and stimulating bone formation appear promising in nonhuman preclinical studies.