Legg-Calvé-Perthes disease (or Perthes disease) is a rare hip condition that affects children.

Over a number of years, the ball-shaped top of a child's thighbone (femoral head) breaks down and re-forms. The disease goes through four phases:

• Initial phase. The femoral head loses its blood supply. The hip joint becomes inflamed, stiff, and painful. Parts of the bone turn into dead tissue. The ball of the thighbone becomes less round. This phase can last from several months up to 1 year.
• Fragmentation phase. The body absorbs the dead bone cells and replaces them with new, healthier bone cells. The femoral head begins to re-form into a round shape. The joint is still irritated and painful. This phase can last from about 1 to 3 years.
• Reossification phase. The femoral head continues to re-form into a round shape with new bone. This phase is often the longest phase and lasts for a few years.
• Healing phase. Normal bone cells replace the new bone cells. This last phase can last a few years to complete the healing process.

The cause of Legg-Calvé-Perthes disease is unknown. It typically occurs in children ages 3 to 12. The majority of cases affect only one hip.

Children with Legg-Calvé-Perthes disease may have:

• Pain in their hip that gets worse with activity
• Pain in the thigh or knee area
• A limp
• Decreased mobility in the hip
• Muscle loss in the upper leg and hip

These symptoms may seem like other health problems of the hip. Make sure your child sees their doctor for a diagnosis.

Your child's doctor will do a complete health history and physical exam of your child. Your child may also need:

• X-rays. This test makes images of internal tissues, bones, and organs.
• Bone scans. This test looks for any breakdown in the joints. It helps find bone diseases and tumors. It can find the cause of bone pain or inflammation.
• MRI. This test uses a combination of large magnets, radio waves, and a computer to make detailed images of organs and structures within the body.

Treatment will depend on your child's symptoms, age, and general health. It will also depend on how severe the condition is.

The goal of treatment is to keep the roundness of the femoral head and to prevent deformity while the condition runs its course. Treatment depends on the amount of hip pain and stiffness. It's also based on X-ray changes over time and how much the femoral head has collapsed.

Treatment may include:

• Rest. Your child may need to limit activity. They may need crutches or a wheelchair. In some cases, your child may need bed rest.
• Medicines. Pain relievers, such as ibuprofen, may help ease pain in the hip joint.
• Physical therapy. This treatment can keep the hip muscles strong and promote hip movement.
• Surgery. Your child may need surgery to hold the femoral head in the hip socket.
• Casting or bracing. This treatment may be tried to help hold the femoral head in the hip socket. But it is used less often now. Surgery is thought to be more effective.

The more severe the case, the greater the likelihood that your child may have limited hip motion, differences in leg lengths, and other hip problems in adulthood.

• Legg-Calvé-Perthes disease is a rare hip condition that affects children. Over a number of years, a child's femoral head breaks down and re-forms.
• The disease has four phases.
• Children with this disease feel pain and stiffness in their hip joint.
• X-rays and bone scans can help diagnose it.
• Treatment goals include controlling pain, maintaining hip motion, and keeping the hip deformity from getting worse.

Tips to help you get the most from a visit to your child's doctor:

• Know the reason for the visit and what you want to happen.
• Before your visit, write down questions you want answered.
• At the visit, write down the name of a new diagnosis and any new medicines, treatments, or tests. Also write down any new instructions your doctor gives you for your child.
• Know why a new medicine or treatment is prescribed and how it will help your child. Also know what the side effects are.
• Ask if your child's condition can be treated in other ways.
• Know why a test or procedure is recommended and what the results could mean.
• Know what to expect if your child does not take the medicine or have the test or procedure.
• If your child has a follow-up appointment, write down the date, time, and purpose for that visit.
• Know how you can contact your child's doctor after office hours, and on weekends and holidays. This is important if your child becomes ill and you have questions or need advice.