Legg-Calve-Perthes disease (LCPD) is idiopathic osteonecrosis or idiopathic avascular necrosis of the capital femoral epiphysis of the femoral head. This condition was described independently by Arthur Legg, Jacques Calve, and Georg Perthes in 1910. This process is also known as coxa plana, Legg-Perthes, Legg Calve, or Perthes disease.