Gradual breaking down and re-forming of the head of the femur (thighbone)
Perthes’ disease is a rare condition in which the head of the femur (thighbone) softens and breaks down, and is gradually replaced by new bone over 18 months to 2 years. The disease causes pain in the hip and sometimes in the knee. An affected child may walk with a limp and have restricted movement of the hip. Perthes’ disease occurs mainly in boys between the ages of 4 and 8 and is more severe in older children. The disease affects 1 in 10,000 children. Of these, 1 in 10 has the disease in both hips.
The cause of Perthes’ disease is not known. The condition requires treatment, and you should consult your doctor if your child develops a limp or has a painful hip or knee.
Initial treatment is bed rest until the pain subsides. In younger children, bed rest may be sufficient, but sometimes traction is used to place the femur under tension and hold it in the correct position. In more severe cases, casts or braces may be used to protect the hip joint and hold the head of the femur securely in the hip socket while the bone re-forms. Occasionally, surgery is required. Your child’s progress will be monitored by X-rays every few months while the head of the femur recovers. He or she will probably have physiotherapy to encourage mobility of the joint during healing.
About 3 in 10 of those affected develop the joint condition osteoarthritis later in life. In general, a complete recovery is more likely in a child under the age of 8 years.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.