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What is Perthes disease?

What is Perthes disease?

Perthes disease is a childhood disorder which affects the top of the femur bone. The femur is the bone in your thigh. It affects the ball part of the ball and socket joint where it meets the hip. In Perthes disease, the blood supply to the top of femur is reduced, making the bone soften and break down. This is known as ‘avascular necrosis’.

This causes the ball of the joint to be flattened, rather than round. This reduces the movement of the hip joint. There are 4 stages to the disease with the end stage being remodelling. This whole process can take between 2 to 4 years.

What is the cause of Perthes disease?

The cause is unknown. It is more likely to happen in boys than girls and most commonly occurs between 4 and 8 year olds.

Signs and symptoms

Signs and symptoms of Perthes disease include:

  • Persistent hip or groin pain, however knee pain may be the only symptom
  • A painful limp may be present
  • Wasting of the muscles in the upper thigh and bottom
  • Loss of movement at the hip, with stiffness and muscle spasms
  • Sometimes shortening of the affected leg

What may my child need?

Your GP may refer your child for an X-ray of the hip, which can diagnose the presence of Perthes disease.

How do I help my child?

Your child should avoid heavy impact on the joint such as running or jumping activities. Encourage swimming and other non-weight bearing activities to help keep your child fit.

Physiotherapists can give exercises to help maintain a full range of motion. Support your child with their physiotherapy.

As your child’s physical activity will be restricted you may need to consider a more healthy diet.


Abduction and adduction

Ask your child to lie on their back, and bring their leg out to the side and then back across the mid position. Repeat 10 times, 3 times a day.

Illustration of adult holding child's ankle and tummyIllustration of adult holding child's tummy and ankle, and pulling their leg outwards

Flexion and extension

Ask your child to lie on their back, bend their knee towards their chest and then lower back down to the surface.

Illustration of adult holding child's ankle and knee and bringing up to chest

Ask your child to lie on their tummy, bend their knee and then lift their foot towards the ceiling. Repeat 10 times 3 times a day.

Illustration of child laying on tummy and adult lifting their knee up

External rotation and internal rotation

Ask your child to lie on their tummy with their knees bent to 90 degrees. Keeping the knees together, take their feet away from each other and then towards each other, just like windscreen wipers. Repeat 10 times 3 times a day.

Illustration of child laid on their tummy and adult crossing their ankles over

Illustration of child laid on their front and adult holding their ankles outwards

The amount of activity your child will be allowed to do will depend on the severity of the condition and the specialist doctor will guide you with this. Please remember that your child’s own specialist is the person to ask about the activities which they feel appropriate for your child.

Treatments advised will depend on the age of your child and the severity of the condition. Treatments may include ‘observation’, crutches, surgery, and short term hospital rest.

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Please note: this is a generic information sheet relating to care at Sheffield Children’s NHS FT. These details may not reflect treatment at other hospitals. This information is not intended as a substitute for professional medical care. Always follow your healthcare professionals’ instructions. If this resource relates to medicines, please read it alongside the medicine manufacturer’s patient information leaflet. If this information has been translated into another language from English, efforts have been made to maintain accuracy, but there may still be some translation errors. If you are unsure about any of the guidance in this resource or have specific questions about how it relates to your child, always ask your healthcare professional for further advice.

Resource number: PT20

Resource Type: Article

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