What is Legg-Calvé-Perthes disease?

Legg-Calvé-Perthes disease (or Perthes disease) is a rare condition in children in which the ball-shaped head of the thigh bone, referred to as the femoral head, loses its blood supply. As a result, the femoral head collapses. Over time, the body absorbs the dead bone and replaces it with new bone, but this process can lead to flattening of the ball. As a result, Legg-Calvé-Perthes disease can cause the hip joint to become painful and stiff for a period of time.

Phases

Legg-Calvé-Perthes disease goes through four phases of changes that affect the head of the femur. The phases include:

• Phase 1 - Initial phase. Blood supply is absent to the femoral head and the hip joint becomes inflamed, stiff, and painful. Portions of the bone turn into dead tissue. The ball of the thigh bone becomes less round in appearance on X-rays. This phase can last from several months up to 1 year.
• Phase 2 - Fragmentation phase. The body starts absorbing the dead bone and forming new bone. During this stage the ball is “soft” and is at risk for flattening even just from the forces every day activities. The joint is usually irritated and painful. A limp is common. This phase can last from 1 year to 3 years.
• Phase 3 - Reossification phase. During this phase, the bone of the ball starts to harden and the femoral head begins to remodel into a round shape again. This phase lasts for 1 year to 3 years.
• Phase 4 - Healing phase. After the bone fully grows back, the shape of the ball continues to develop until a child stops growing. 

Causes of Legg-Calvé-Perthes disease

The cause of Legg-Calvé-Perthes disease is unknown. It is four times more likely to occur in boys than girls and is uncommon in African-Americans.

Legg-Calvé-Perthes disease can be seen in children 2 years to 12 years of age, with most children being 6-9 years of age. The majority of cases affect only 1 hip, although 10% of the time both hips can be affected.

Symptoms of Legg-Calvé-Perthes disease

The child typically complains of pain in his or her hip that is aggravated by activity. Sometimes, they will also experience pain in their thigh or knee area. The child usually walks with a limp and reports that rest will alleviate the pain. Over time, you may notice muscle loss in the upper leg and hip.  

The symptoms of Legg-Calvé-Perthes disease may resemble other conditions or medical problems of the hip. Always consult your child's doctor for a diagnosis.

Diagnosis of Legg-Calvé-Perthes disease

In addition to a complete medical history and physical examination, diagnostic procedures for Legg-Calvé-Perthes disease may include:

• X-rays. A diagnostic test that uses invisible electromagnetic energy beams to produce images of internal tissues, bones, and organs onto film.
• Magnetic resonance imaging (MRI). A diagnostic procedure that uses a combination of large magnets, radiofrequencies, and a computer to produce detailed images of organs and structures within the body.
• Perfusion MRI. A specialized type of MRI using dye (contrast) injected through an IV that allows doctors to understand areas of the hip that are getting good blood flow and areas where blood flow is deficient. This is one of the best tests to identify Perthes early before irreversible changes occur.  CHOP is one of the only hospitals in the area that has special perfusion MRI techniques specifically designed for children with Perthes disease, and has been a leader nationally in the development of this new technology.

Treatment for Legg-Calvé-Perthes disease

Specific treatment for Legg-Calvé-Perthes disease will be determined by your child's doctor based on:

• Your child's age, overall health, and medical history
• The extent of the condition
• Your child's tolerance for specific medications, procedures, or therapies
• Expectations for the course of the condition
• Your opinion or preference

The goal of treatment is to preserve the roundness of the femoral head and to prevent deformity while the condition runs its course. Treatment options are dependent on the amount of hip pain, stiffness, and X-ray changes over time, as well as how much of the femoral head has collapsed.

Although there is some controversy about the pros and cons of various treatment options, the principles of treatment in Perthes are the same. The first goal is to regain hip motion and keep the ball as round as possible in order to maximize the function of the hip into adulthood. 

Containment is another major guiding principle in the treatment of Perthes disease. Containment refers to the concept of keeping the soft ball (femoral head) deep within the socket (acetabulum) so that the socket itself acts as a mold to keep the ball round. There are several ways to “contain” a hip, and your doctor will discuss the best options with you during your visit. Depending on the stage of the severity of disease, treatment may include::

• Rest
• Activity restrictions
• A period of reduced weightbearing with crutches and/or a wheelchair
• Physical therapy (to keep the hip muscles strong and to promote hip movement)
• Medications, such as ibuprofen
• Casting or bracing (to hold the femoral head in the hip socket, permit limited joint movement, and allow the femur to remold itself into a round shape again) 
• Bony surgery on the femur (thigh bone) or the socket to contain the femoral head in the hip socket

Consequences of Legg-Calvé-Perthes disease as a young adult

Some patients who are initially well-treated for Perthes disease may develop more pain and symptoms as older teenagers and young adults. This usually occurs from the residual shape of the hip after the hip has fully healed. 

CHOP’s Young Adult Hip Preservation Program specializes in the management of these patients. In many cases, symptoms can be alleviated and function improved by physical therapy, selective injections and/or specialized hip preservation surgeries. 

Long-term outlook

The ultimate goal in Legg-Calvé-Perthes disease is to preserve the flexibility of the hip joint and the roundness of the femoral head. Ideally, the condition is diagnosed early so that flattening (collapse) of the femoral head can be minimized and containment principles can be used to remodel the ball back into a round shape.

The two most critical factors that determine the outcome are the child's age at diagnosis and how much of the femoral head is affected by this condition.

Early treatment at centers with experience can help preserve the shape of the hip, but patients are still at risk for having hip problems as adults. The more severe the case, the greater the likelihood that the child may experience limited hip motion, differences in leg lengths, and early arthritis requiring a hip replacement later in life.