The Department of Orthopaedic Surgery

Pediatrics

Patient Guide to Perthes Disease

Perthes Disease is a disorder of the hip in young children. The blood supply to the femoral head (the "ball" that is the upper part of the femur that inserts into the socket of the hip) is interrupted. The femoral head then "necroses" (i.e. loses blood supply) which weakens the bone and can lead to a fracture. The bone is then taken up by the body (or resorbed) which can lead to a complete collapse of the femoral head. Later in life, degenerative joint disease (very much like osteoarthritis) can develop.

It all sounds very complicated, but basically what happens is that the femoral head dies from lack of blood, collapses, and is resorbed. Perthes affects less than 1% of the general population and is therefore very rare.

Does Perthes disease run in the family?

Studies have shown that the children with parents that have the disease are more likely to get it. In fact, between 2% and 10% of children with Perthes disease have at least one family member with the disease.

What are the signs and symptoms of Perthes disease?

The most common way a parent notices that something is not right is the insidious development of a limp. A patient will actually lean the pelvis over the affected limb when putting weight on it. The child might complain of mild pain in the groin area, thigh, or knee. This pain is usually worse with activity and improves with rest.

The doctor looks to see if the child has problems rotating the leg. The thigh, calf, and buttock muscles can "atrophy" (i.e. become smaller) if the affected limb goes a long time without use. The doctor may notice that the affected leg is shorter than the normal leg in cases where Perthes disease has been going on for a long time.

Radiograph of patient with Perthes.

What causes Perthes disease?

The cause is currently not known. There are several theories. As mentioned above, the supply of blood to the femoral head is lost. The reasons for this, however, are unclear. It might be due to trauma that damages the blood vessels or disorders which cause the blood to clot and clog up the veins.

What is the treatment for Perthes disease?

In general, it is very important to keep the joint moving. This is because the cartilage on the femoral head depends on the liquid in the joint (called the "synovial fluid") for its nutrition. Moving the hip helps to supply the cartilage with this fluid.

Is there surgery involved in the treatment?

Surgery may be warranted to treat Perthes disease, but is not recommended for children under the age of 6 years old unless the femoral head is not anywhere near its normal location. The pediatric orthopaedic surgeon may break the bones of the femur and/or acetabulum (the cup that fits around the femoral head) and fix them in a more anatomically correct position. This procedure, called an "osteotomy," allows the femoral head to grow in its normal spherical fashion. It is important to put the head back into the cup.

The position of the head is determined by doing x-ray studies. If the doctor is able to put the head back into the acetabulum (the cup), it may help to use casts to keep it there. If the head does not fit back into the acetabulum, other procedures may be needed to reduce pain and help the child with movement.

Radiograph of patient after
osteotomy surgery

Are there complications of Perthes disease to know about?

Yes. The head of the femur may lose its normal, spherical shape and/or collapse. Also, degenerative joint disease can occur (i.e. as occurs in osteoarthritis). The affected leg may lose some of its motion and may become shorter than the normal leg.

How will my child with Perthes disease do in the long run?

This varies from patient to patient. The presence of some signs usually carries a worse prognosis. These include the development of Perthes when the child is older than 8 years old, the development of a poor range of motion, and the presence of a non-round femoral head even after treatment. In most patients, pain resolves during the teenage years. However, it is estimated that approximately 50% of patients who develop Perthes disease as a child will need hip replacement by later adulthood (i.e. 50 to 60 years of age).

For more information, please contact the following site:

Perthes Assocation: http://www.perthes.org.uk

National Osteonecrosis Foundation: http://www.nonf.org

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