1) Perthes disease is avascular necrosis of the femoral head that typically affects children between the ages of 4-8. It has an unknown etiology but is thought to be related to insufficient blood supply to the femoral head.
2) On x-ray, the disease progresses through stages of avascular necrosis, fragmentation, revascularization, and healing. Classification systems describe the extent of involvement and prognosis.
3) Treatment aims to contain the femoral head within the acetabulum during revascularization to encourage spherical remodeling. Conservative methods use bracing and casting while surgical methods include femoral and pelvic osteotomies. The goal is containment until late regeneration is complete around 2 years.