Legg-Calve-Perthes Disease

What is Legg-Calve-Perthes disease?

Legg-Calve-Perthes disease (also known as Perthes disease) is a rare condition in which the ball-shaped head of the thighbone (femoral head) temporarily loses its blood supply. As a result, the head of the thighbone collapses, and the area becomes inflamed and irritated.

As the condition runs its course, the body will absorb the dead bone cells and replace them with new bone cells. The blood supply will eventually return and the femoral head will heal. But the shape of the femoral head will have changed and no longer move smoothly in the hip socket. If left untreated, Perthes disease can cause arthritis later on.

For the majority of children with Perthes disease, only one hip is ever affected. In 10 to 12 percent of children with the condition, both hips are affected though usually not at the same time.

A healthy hip compared to a hip joint with Legg-Calve-Perthes disease. In the healthy hip, the femoral head is round and fits securely into the hip socket. In the hip with Perthes disease, the femoral head has flattened out, and there’s a pocket of empty space in the socket. The surrounding area is red and inflamed.

What are the symptoms of Legg-Calve-Perthes disease?

Signs and symptoms of Perthes disease can include:

  • walking with a limp (can be a “painless limp”)
  • limited range of motion and stiffness in the hip, groin, thigh, or knee
  • pain in the hip, groin, thigh, or knee that gets worse during activity

What causes Legg-Calve-Perthes disease?

Perthes disease is idiopathic, which means that there is no known cause for this condition. What is clear is that when blood supply to the femoral head is disrupted, the bone starts to break down.

About one out of every 12,000 children develop Perthes disease. Boys are five times more likely to be affected than girls, but when girls are affected, the condition tends to be more severe.

Perthes disease most often affects children who are between 4 and 10 years old, very physically active, and small for their age. The condition tends to be more common in children who have been exposed to second-hand smoke.

What are the stages of Legg-Calve-Perthes disease?

Legg-Calve-Perthes disease takes place in four phases:

Phase 1: Necrosis

The blood supply to the femoral head is disrupted, causing the hip joint to become inflamed, stiff, and painful. Areas of the bone turn into dead tissue (avascular necrosis). In x-rays, the femoral head appears less round. This phase can last from several months up to one year.

Phase 1: Necrosis. Interrupted blood flow to the head of the femur causes the femoral head to become misshapen and a pocket to open up in the hip socket.

Phase 2: Fragmentation

The body “cleans up” the dead bone cells and replaces them with new, healthy bone cells. The femoral head begins to remodel into a round shape again, but the joint is still inflamed and painful. This phase can last up to two years.

Phase 2: Fragmentation. As the interrupted blood flow continues, the pocket in the hip socket grows larger.

Phase 3: Reossification

The femoral head continues to remodel itself back into a round shape with new bone once blood flow is restored. This phase can last from one to three years.

Phase 3: Reossification. Healthy blood flow returns to the head of the femur and new bone grows, making the gap in the socket smaller.

Phase 4: Remodeling

Normal bone cells replace the new bone cells, and the femoral head becomes more of a mushroom shape than a ball. This phase can last a few years as the bone heals.

Phase 4: Remodeling. Healthy blood flow continues but the femoral head is flat and slightly indented and the gap in the hip socket remains.

How we care for Legg-Calve-Perthes disease

Specialists in Boston Children’s Child and Young Adult Hip Preservation Program have deep experience diagnosing and treating children with Legg-Calve-Perthes disease. In fact, Boston Children’s orthopedic surgeon Arthur Thornton Legg, MD, was the one of the first to recognize and describe Legg-Calve-Perthes disease in 1910. Our specialists have continued to lead the way in pioneering advanced techniques for treating this condition.

Our expansive team of pediatric orthopedic hip specialists provide world-class care throughout each patient’s journey, collaborating over both common and complex hip disorders to provide our patients comprehensive care. Our goal is the same as yours: to help your child get better so they can return to being healthy and pain-free.

Patient and family resources

Download our patient fact sheet for Legg-Calve-Perthes disease to learn more.