Legg-Calve-Perthes disease is a temporary condition in children in which the ball-shaped head of the thigh bone (femur), also known as the femoral head, loses its blood supply. Hence, the femoral head collapses. The body will absorb the dead bone cells and replace them with new bone cells, eventually reshaping the femoral head of the thigh bone. The femur is the large bone in the thigh, and the femoral head is the rounded ball at the end of the bone that fits into the hip socket. Legg-Calve-Perthes disease causes the hip joint to become painful and stiff for a short period of time.
Legg-Calve-Perthes disease is also known as avascular necrosis or Chandler disease in adults. Avascular necrosis is a disease resulting from the temporary or permanent loss of the blood supply to the bones. Without blood, the bone tissue dies and causes the bone to collapse. Avascular necrosis usually affects people between 30-50 years of age. This monograph pertains to Legg-Calve-Perthes disease in children.
Approximately one in 1,200 children younger than 15 years is affected, usually aged two to 12 years. Legg-Calve-Perthes disease typically affects one hip, but sometimes it develops in both hips. The disease affects both joints in 10-20% of children. When both hips are involved, they are usually affected one after the other and not at the same time. A family history is present in 6% of patients.
Legg-Calve-Perthes disease goes through four phases of changes that affect the head of the femur.
Phase 1: Blood supply is absent to the femoral head and the hip joint becomes inflamed, stiff, and painful. Portions of the bone turn into dead tissue. The ball of the thigh bone becomes less round in appearance on x-rays. This phase can last from several months up to one year. The individual can still walk.
Phase 2: The body cleans up the dead bone cells using the immune system
and replaces them with new, healthier bone cells. The femoral head begins to remodel into a round shape again. The joint is still irritated and painful. This phase can last from one to three years.
Phase 3: The femoral head continues to model itself back into a round shape with new bone. This phase lasts for one to three years.
Phase 4: Permanent bone cells replace the new bone cells. This last phase can last a few years to complete the healing process.
The long-term outlook for Legg-Calve-Perthes disease is often good, especially for children who develop the condition very young. The younger the child, the more time there is to reshape the affected hip bone.
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