Perthes' Disease

What is Perthes' disease?

Perthes' disease is a condition of the hip which occurs in some children. It was first described in 1910 by three separate doctors and so it is sometimes called Legg-Calve-Perthes' Disease after each of these doctors.

What happens in Perthes' disease?

Who gets Perthes' disease?

About 1 in 10,000 children between the ages of 2 and 15 years develop Perthes' disease each year. It occurs most commonly between the ages of 4 and 8 years. About four boys are affected for every one girl. It usually only occurs in one hip, but in about 1 in 8 cases it occurs in both hips (at separate times).

What are the symptoms of Perthes' disease?

Symptoms tend to develop gradually and can include:

• Limp. This may gradually become worse over a few weeks.
• Pain in the hip and groin area. The pain may radiate to the knee or thigh. Sometimes the pain is felt in the knee, instead of in the hip - this is called 'referred pain'.
• Stiffness and reduced range of movement of the affected hip.
• In time, the affected leg may become slightly thinner (wasted), because it is not used as much as the other leg.
• The affected leg may look shorter than the 'good' leg.

How is Perthes' disease diagnosed?

A GP will normally refer a child with suspected Perthes' disease to a specialist. The diagnosis can usually be made by a doctor's examination of the hip, plus an X-ray (this is usually an X-ray of both hips so that the two sides can be compared).

Sometimes other tests may be helpful, if the diagnosis is not clear or if a more detailed picture of the hip joint is needed. Possible tests are: an MRI scan, a bone scan and an arthrogram (an X-ray where dye is injected into the joint space). Sometimes blood tests, or a sample of fluid from the joint, may be needed to rule out other problems such as infection.

What is the treatment for Perthes' disease?

The aim of treatment is to promote the healing process and to ensure that the femoral head remains well seated in the hip socket as it heals and regrows. Treatment depends on the age of the child and the severity of the condition. Treatments may include 'observation', bed rest and crutches, a plaster cast or special leg brace, or surgery.

Observation and physiotherapy

In the past, children with Perthes' disease were treated with a plaster cast, a brace, or surgery. However, it is now known that at least half of cases heal well without any treatment, particularly children aged five and under, and milder cases.

Most children with Perthes' disease can be treated by physiotherapy and home exercises - these are to keep the hip joint mobile and in a good position in the hip socket. Your child will need regular reviews to check how the femoral head is healing. Advice may include to encourage swimming (to keep the hip joint active in the full range of movements), but to avoid heavy impact on the joint such as running or jumping. However, advice will be tailored to your child's needs.

Bed rest and/or crutches

May be needed for a short time at first if symptoms are bad.

Plaster casts or a special brace

These may be considered in more severe cases or in older children. The aim is to keep the femoral head well positioned in the hip socket. So these devices keep the leg slightly 'abducted' (slightly pointing outwards). Special braces (also called called 'orthotic' devices') may be advised. With many of these, the child can walk and weight bear, but they may need to be worn for many months.

Surgery

An operation may be considered in some cases. Surgery can help to keep the femoral head well positioned whilst it heals, or can improve the shape and function of the joint if it has not healed well. There are various options, depending on each child's individual situation.

What is the outcome (prognosis)?

In most cases the femoral head regrows and remodels back to normal or near normal. The function of the hip then returns to normal. It can take two or more years (even several years) for this to occur after the condition first starts.

The main concern is that the femoral head may not reform properly, so that 'flattening' of the femoral head can occur in some cases. In this situation a permanent change in the joint may remain. This can cause permanent stiffness of the hip joint. It can also cause arthritis of the hip joint at an earlier age than usual, for example, at around age 40.

Factors which may affect outcome include:

• Age. The younger the child when the condition develops, the better the chance of a good outcome. This is because they have longer to grow and this gives more time for the hip to remodel before the child finishes growing. Children who develop Perthes' disease after about the age of 8-9 have the highest risk of persisting problems.
• Gender. For any given age when the condition develops, boys have a better chance of a good outcome than girls. This may be because girls tend to finish growing a bit earlier than boys.
• Severity. The more severe the condition (which can be judged by the X-ray pictures of the hip), the greater the risk that problems will persist.

Further help and information

Perthes' Association

PO Box 773, Guildford, GU1 1XN
Helpline: 01483 306637 Web: www.perthes.org.uk

Perthes' Association Scotland

29 Leander Crescent, Deanpark Estate, Renfrew, PA4 0XB
Tel: 0141 885 0001 or 0141 561 0001