• Reference Number: HEY1496/2024
• Departments: Paediatrics, Physiotherapy
• Last Updated: 31 July 2024

What is Perthes?

Perthes is a condition that affects the hip joints in children. The hip joint is a ball (femoral head) and socket (acetabulum) joint. This leaflet has been produced to give you some information on the condition but should not replace discussion between yourself and your child’s doctor.

The cause is unknown, but it is known that the blood supply to the ball of the hip is disrupted.  This will eventually lead to softening of part or all of the ball of the hip.  Consequently, the ball becomes soft and loses its round shape becoming more like a ‘rugby ball’ in appearance.

Ultimately the blood supply recovers, and new bone will be made in the ball part of the joint.  However, the ball will not return to its original round shape.

The whole process may last 3 to 4 years from initial symptoms to full regeneration of the bone.

What are the facts?

Perthes affects children between the ages of 3 to 12 years, but most commonly begins between 5 to 8 years.  It affects children at a rate of 1 in 9000.

Boys are affected four times more frequently than girls.

Occasionally both hips can be involved but onset is not usually at the same time.

What are the symptoms?

Your child may experience the following:

• Reduced movement in the hip joint.
• Pain in the hip / groin and / or knee joint, which may present as fidgeting
• Limping due to pain, muscle weakness or reduced movement.

Symptoms can vary from day to day and can occur suddenly without any reason.

How is it diagnosed?

Perthes, once established, can be diagnosed by an x-ray, however, it is difficult to diagnose in the early stages.  This is because the first symptoms are due to inflammation of the joint and this does not appear on an x-ray.  Therefore, your child may have had problems for 6 months or longer before diagnosis.

How is it treated?

Treatment, although important, cannot cure this condition.  The blood supply recovers as part of the body’s own repair process. Therefore, the main aim of treatment is to encourage the shape of the ‘ball and socket’ joint to remain round and maintain mobility.

Consultants both within the same hospital and at different hospitals often treat Perthes differently.  Your consultant may restrict certain activities, e.g. high impact / running / jumping, for part or all of the Perthes process.

If your child is in a lot of pain, he/she may require an Orthopaedic Consultant review. If the movement is very poor and the ‘ball and socket’ joint does not fit together properly then surgery may be required.  This may mean your child being in plaster casts for 6 weeks or non-weight bearing using crutches or a zimmer frame.

What other treatment is there?

Physiotherapy plays a large part in the treatment of Perthes and consists of exercises to help maintain the hip joint range of movement, improve muscle power and ease pain.  This may be done regularly at Hull Royal Infirmary, but you will be taught a home exercise programme to enable regular completion. Exercise and movement are good for children; therefore, they are encouraged to swim with parents if possible and participate in activities / PE, although they may have to be adapted slightly to accommodate any restrictions.

Children sometimes find walking long distances can cause pain in the hip, therefore a wheelchair, which will be referred for by your therapist, can be of benefit in these circumstances; it may need to be used to and from school but should not be required around school.

Children may find sitting cross-legged painful, especially for prolonged periods, and so they may benefit from sitting on a chair rather than the floor

What is the outlook for my child?

Children with Perthes usually recover function once new bone is formed.  They may lack some movement but manage to participate in most sports and activities.

Your child may develop arthritis in later life, depending on the final shape of the hip joint and the age of the child when the condition was diagnosed.  The younger a child is when they develop Perthes generally the better the outcome.

This leaflet was produced by the Children’s Physiotherapy & Occupational Therapy Department, Hull University Teaching Hospitals NHS Trust and will be reviewed in July 2027.

General Advice and Consent

Most of your questions should have been answered by this leaflet, but remember that this is only a starting point for discussion with the healthcare team.

Consent to treatment

Before any doctor, nurse or therapist examines or treats your child, they must seek your consent or permission. In order to make a decision, you need to have information from health professionals about the treatment or investigation which is being offered to your child. You should always ask them more questions if you do not understand or if you want more information.

The information you receive should be about your child’s condition, the alternatives available for your child, and whether it carries risks as well as the benefits. What is important is that your consent is genuine or valid. That means:

• you must be able to give your consent
• you must be given enough information to enable you to make a decision
• you must be acting under your own free will and not under the strong influence of another person

Information about your child

We collect and use your child’s information to provide your child with care and treatment. As part of your child’s care, information about your child will be shared between members of a healthcare team, some of whom you may not meet. Your child’s information may also be used to help train staff, to check the quality of our care, to manage and plan the health service, and to help with research. Wherever possible we use anonymous data.

We may pass on relevant information to other health organisations that provide your child with care. All information is treated as strictly confidential and is not given to anyone who does not need it. If you have any concerns please ask your child’s doctor, or the person caring for your child.

Under the General Data Protection Regulation and the Data Protection Act 2018 we are responsible for maintaining the confidentiality of any information we hold about your child. For further information visit the following page: Confidential Information about You.

If you need information about your child’s (or a child you care for) health and wellbeing and their care and treatment in a different format, such as large print, braille or audio, due to disability, impairment or sensory loss, please advise a member of staff and this can be arranged.