What Is Legg-Calvé-Perthes Disease?

Legg-Calvé-Perthes (leg cal-VAY PER-teez) disease, often called Perthes disease, is a problem that changes the hip joint and the way bone grows at the top of the thighbone (femur). It most often happens in one hip, but can affect both. 

It may lead to:

• stiffness in the hip joint
• hip arthritis as an adult
• one leg being shorter than the other (called leg length discrepancy)

What Happens in Legg-Calvé-Perthes Disease?

The hip is the joint where the leg meets the body. The top of the thighbone is ball-shaped. It fits inside a round socket. This ball and socket joint lets us move our legs around in all directions.

In Perthes disease, not enough blood reaches the ball of the hip. As a result:

• Bone cells in the ball of the hip starve and die.
• The body starts to break down the ball of the hip.

After a few months, the body starts to rebuild the bone. The rebuilt part could be normal, flattened, or enlarged. If the rebuilt ball is not normal, it may not fit well inside the hip socket, causing problems with moving the hip. The changes happen slowly. It usually takes about 2–3 years from the time symptoms start until the bone is finished rebuilding.

What Are the Signs & Symptoms of Legg-Calvé-Perthes Disease?

Perthes disease can cause:

• Limping: Often the first sign of Perthes is a limp. Parents might notice a change in the way their child walks or runs during sports. One hip may seem stiff or have less movement.
• Pain: Most kids have some pain in the hip, groin, thigh, or knee.

These problems may come and go, and usually:

• begin slowly
• stay mild
• are on one side, but may involve both hips
• are worse with activity and get better with rest

What Causes Legg-Calvé-Perthes Disease?

Doctors don't know what causes Perthes disease.

Who Gets Legg-Calvé-Perthes Disease?

Most kids who develop Perthes are between 4 and 10 years old. It happens more often in boys than in girls.

How Is Legg-Calvé-Perthes Disease Diagnosed?

When a child has signs of Perthes disease, the doctor will:

• ask about the symptoms
• do an exam to check the hip's movement
• order X-rays
• possibly order blood tests to make sure another problem isn't causing the symptoms

Kids with Perthes disease will have X-rays repeated during care, which can last for several years. In the condition's early stages, bone changes don't always show up on an X-ray. So the doctor may order another test, such as an MRI (magnetic resonance imaging).

How Is Legg-Calvé-Perthes Disease Treated?

A specialist in children's bone problems (a pediatric orthopedist or orthopedic surgeon) most often treats children with Perthes disease. Treatment goals are to:

• decrease pain
• help the bones heal so the hip works the best it can. The better the bone heals, the less chance the hip joint will "wear out" later and develop early arthritis.

Treatment may include:

• medicine for pain and inflammation
• putting less weight on the hip joint. Kids usually need to stop running and jumping for a while. Some kids may need to use crutches or a walker for a few weeks or months.
• wearing a brace or cast
• physical therapy (PT)

Some children with Perthes disease may need surgery. Sometimes the leg affected by Perthes disease is shorter and may need either a lift in the shoe or, rarely, surgery.

What Else Should I Know?

Most children with Perthes disease will heal well and have no long-term problems. The degree of recovery depends on how much of the bone is involved. Kids who have only a small area of bone affected tend to heal the best. Also, younger children tend to heal better than older kids.

A child who has ongoing problems might:

• need surgery to make the hip work as well as possible and put off the need for hip replacement surgery
• develop hip pain and arthritis as a young adult
• need hip replacement surgery at a younger age than most adults who get a replacement

When Should I Call the Doctor?

Call the doctor right away if your child has a limp and hip pain. Go to the emergency department right away if your child also has a fever. Doctors there can make sure there isn't some other problem, like an infection.