(See also Overview of Bone Disorders in Children.)
Legg-Calvé-Perthes disease is an osteochondrosis, which is a group of disorders of the growth plate of bones that occur when the child is growing rapidly. Doctors are not sure what causes osteochondrosis, but the disorders do seem to run in families. Osgood-Schlatter disease, Köhler bone disease, and Scheuermann disease are other osteochondroses.
Legg-Calvé-Perthes disease develops most commonly among boys between the ages of 5 and 10. The disease usually affects only one leg. About 10% of children have a relative who has the disease. It is caused by a poor blood supply to the upper growth plate of the thighbone (femur) near the hip joint. The poor blood supply causes the end of the thigh bone to die and collapse (avascular necrosis or osteonecrosis). The reason for the poor blood supply in Legg-Calvé-Perthes disease is not known. Other problems also can interrupt blood supply to the growth plates. Such problems include sickle cell disease and taking corticosteroid drugs. However, hip damage from these and other known causes is not considered Legg-Calvé-Perthes disease.
Legg-Calvé-Perthes disease can cause severe hip damage without causing significant symptoms at first. The severe damage may, however, lead to permanent arthritis of the hip. The first symptom of Legg-Calvé-Perthes disease often is pain in the hip joint and trouble walking. Pain begins gradually and progresses slowly. The pain tends to worsen when moving the hip or walking. Some children complain of pain only in the knee. A limp can develop, sometimes before the child has much pain. Eventually, joint movement becomes limited, and the thigh muscles may become wasted (atrophied) from lack of use.
The diagnosis of Legg-Calvé-Perthes disease is confirmed by x-rays. An MRI is done if x-rays are normal or the doctor needs more information on the severity. Later x-rays may show changes around the growth plate, such as a fracture or destruction of the bone.
Doctors take x-rays of the child's skeleton if the disorder runs in the child's family or both of the child's legs are affected. These x-rays are taken to rule out hereditary disorders of the skeleton.
Blood tests are done to rule out other disorders. Doctors try to determine whether the symptoms resulted from an injury.
Treatment of Legg-Calvé-Perthes disease includes prolonged bed rest and immobilization of the hip (for example, with a cast or splint). The choice of treatment depends on the child's age and amount of bone damage. Sometimes the partial immobilization provided by bed rest is sufficient. However, sometimes nearly total immobilization using traction, slings, plaster casts, or splints for 12 to 18 months is necessary. Such treatments keep the legs rotated outward.
Physical therapy is used to keep the muscles from tightening up and wasting away.
If a child is over age 6 and has moderate or severe bone destruction, surgery may be helpful.
Even without treatment, Legg-Calvé-Perthes disease usually gets better, but it takes longer, usually 2 to 3 years, and there is an increased risk of hip arthritis developing later in life.
Treatment with bisphosphonates (drugs that help increase bone density) has been effective, but more studies are needed.