Perthes Disease

Legg Calve Perthes syndrome is a degenerative disease of the hip joint, where growth/loss of bone mass leads to some degree of collapse of the hip joint and to deformity of the ball of the femur and the surface of the hip socket. The disease is typically found in young children, and it can lead to osteoarthritis in adults. The effects of the disease can sometimes continue into adulthood. It is also known more simply as Perthes disease, Legg Perthes Disease or Legg Calve Perthes Disease (LCPD). It is named for Arthur Legg, Jacques Calvé and Georg Perthes and was first described by Karel Maydl.

Causes of Calve Perthes Disease

Perthes disease affects the top of the femur (thigh bone) where it meets the hip bone. The blood supply to the growth plate of the bone (epiphysis) becomes inadequate. As a result, the bone softens and breaks down - a process called necrosis.
This happens gradually over several weeks. Then, as the blood supply recovers, the bone reforms and hardens. This takes 18 to 36 months and may lead to a deformed shape, with flattening of the ball-shaped head of the femur that normally fits into the round socket of the hip joint. Recent research has suggested Perthes' may be linked to a subtle problem with blood clotting.

What are the symptoms?

• The first sign of Perthes' hip disease is usually hip or groin pain, or a limp. Knee pain can also be an early symptom.
• The pain persists and there may be wasting of the muscles in the upper thigh, shortening of the leg and stiffness of the hip, which can restrict movement and cause problems with walking.
• When Perthes' disease has been present for a long time, the affected leg may be shorter and thinner than the unaffected one.

Who's affected?

Perthes' is a hip disorder which most commonly affects children between the ages of four and eight, but younger children and teenagers can also develop the condition. It affects around one in 20,000 children and is up to five times more common in boys. It's also more common among Caucasians. In ten to 20 per cent of cases, both hips are affected.

Stages of Legg-Calvé-Perthes Disease

Initial stage - The femoral head stops growing and remains smaller than the unaffected side.
Resorptive or fragmentational stage - During this stage, the dead bone is removed or reabsorbed by the healing process. Because the dead bone is removed from the femoral head and the loss of bone weakens the strength of the femoral head, it can become flattened or collapsed. With the removal of the dead bone, the femoral head starts to break up into fragments, thus the stage being called fragmentational stage. In some patients, this stage can take one to two years to complete.
Reossification stage - Slowly new bone starts to fill in the areas where the dead bone has been removed. Since ossification means bone formation, this stage is called the stage of reossification.
Healed stage - The femoral head has completely healed itself. Because the femoral head will heal itself, the disease is often said to be "self-healing" or "self-limiting." However, it is important to know that self-healing does not mean that the femoral head will always heal back to its original round shape. The age of the patients at the time of diagnosis and the extent of the femoral head damage may affect how well the femoral head will heal itself back to its normal round shape.

How's it diagnosed?

If a child with hip pain has limited hip movement, an x-ray will be taken to check for Perthes'. In the early stages of the disease this may be normal, so the x-ray must be repeated if symptoms persist. Bone scans, MRI scans and other tests may also be used.

What's the treatment?

The aim of treatment is to reduce hip pain and stiffness, prevent deformity of the head of the thigh bone, and achieve and maintain a full range of movement in the hip joint.
Treatment depends on the severity of the condition. In mild cases, where less than half the head of the femur is affected, bed rest and traction may be all that are needed. In more severe cases, the femur may have to be splinted in position using a plaster cast or calipers. Occasionally, surgery is required.
Most children recover well with minimal long-term problems, especially if they're under six and the disease is mild. But in older children where more than half the head of the femur is affected, there's an increased risk of deformity and arthritis later in life.