Perthes' disease

Disclaimer: This fact sheet is for education purposes only. Please consult with your doctor or other health professional to make sure this information is right for your child.

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What is Perthes' disease?

Perthes' disease is a disorder of the hip joint in children. Children often have difficulty in describing their initial symptoms. In the early stages of Perthes' disease, your child will have a limp that often comes and goes. The limp may get worse as the disease progresses. Eventually, your child may feel pain in the knee, thigh or groin when they put weight on the leg or move the hip joint. Also, there will be less movement in the hip joint. If your child has had the condition for a long time, the affected leg may be slightly thinner and shorter.

Despite pain and limping, these children are healthy. Perthes' disease usually affects children between the ages of three and eleven years. It is more common in boys than in girls. Only one hip is affected in over three-quarters of children.

What causes Perthes' disease?

The cause of Perthes' is unknown. The disease has several phases: Initially, there is a temporary loss of blood supply to the ball-shaped end of the thighbone, (called the femoral head). The lost blood supply causes the ball to soften and collapse. This collapse causes the round femoral head to become flattened or deformed like a mushroom. It no longer fits perfectly in its socket. In fact, as it heals, it may even grow outside the socket. Most children with Perthes' disease recover completely. However, it may take from two to five years to repair the damaged bone. If the femoral head is not seriously deformed, normal hip function will return. Major deformity may lead to persisting stiffness and premature arthritis of the hip.


In the early stages, evidence of Perthes' disease cannot always be diagnosed by x-ray. Your doctor may request a bone scan, ultrasound or MRI scan so that the correct diagnosis can be made. These tests are not usually needed if the appearance on the x-ray is typical of Perthes disease.


Treatment aims to reduce hip pain and stiffness, and prevent deformity of the femoral head. The treatment your doctor prescribes will depend on your child's age and the severity of your child's condition.

Mild condition or child under five

If your child is less than five years old, or if the hip joint is only mildly affected, your child may need no immediate treatment. If there is pain or stiffness, they will need bed rest to relieve the hip joint from weight-bearing movements. Your child should not take part in any high-impact activities, like jumping or running, until the joint is healed. However, swimming and gentle cycling are OK. They will also need regular checkups with their doctor to monitor their condition.

Child over five

Children who are diagnosed aged over five will require careful evaluation to decide if they require more complex treatment. Non-surgical treatment aims to keep the ball of the joint deeply seated inside the socket. This is done with a brace or plaster cast that restricts some movement but allows weight bearing and walking. The brace or cast usually needs to be worn for one or two years. If the femoral head is severely deformed, or your child refuses to wear a brace, surgery may be needed. The aim of surgery is to optimize your child's hip function and promote regular physical activity. Your doctor will discuss appropriate surgical options with you.

Surgery can also be required after the Perthes is healed to optimize the child's hip function and allow them to be as active as possible in late childhood and early adult life.

Emotional support

Children with Perthes' disease are otherwise healthy and usually want to lead the same active lifestyle as their peers. If you try to limit their activity, they may become frustrated and anxious. Be understanding and supportive. Help your child to find other activities they enjoy that do not require too much weight bearing on the affected leg. Recovery is a long, slow process. Reassure your child that they will recover and will eventually be able to resume their regular physical activities.


  • Recovery is a slow process. Be patient and explain this to your child.
  • Most children recover completely.
  • Avoid high impact activities, like running and jumping, until the hip joint heals.

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Sydney Children's Hospital, Randwick
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