Perthes disease

Perthes' disease is a condition where the top of the thigh bone (the femoral head) softens and breaks down. It occurs in some children and causes a limp and other symptoms. The bone gradually heals and reforms as the child grows. The aim of treatment is to ensure that the femoral head reforms back into its normal shape so that the hip joint can work well.

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 Calvé-Legg-Perthes disease after each of these doctors.

What happens in Perthes' disease?

Perthes' disease occurs in a part of the hip joint called the femoral head. This is the rounded top of the femur (the thigh bone) which sits inside the acetabulum (the hip socket). Something happens to the small blood vessels which supply the femoral head with blood. So, parts of the femoral head lose their blood supply. As a result, the bone cells in the affected area die, the bone softens, and the bone can fracture or become distorted. The severity of the condition can vary.

Over several months the blood vessels regrow, and the blood supply returns to the bone tissue. New bone tissue is laid down, and so the femoral head reforms and regrows. This is similar to how bone reforms and regrows after any normal fracture or break to a bone. But, with Perthes' disease, it takes longer (up to several years). The main concern with regrowth of the femoral head is to ensure that it forms a good spherical (rounded) shape. This helps it to fit well into the hip joint socket. If the femoral head is less rounded, hip movements may be affected and there may be more wear and tear on the hip joint.

The exact cause of the blood vessel problem that occurs in the first place is not known. A child with Perthes' disease is usually otherwise well.

Perthes' disease usually only affects one hip, but in about 1 in 6 cases it affects both hips (usually at separate times).

Who gets Perthes' disease?

In the UK, about 1 in 1,000 children will get Perthes' disease. It occurs most commonly between the ages of 4 and 8 years. About four boys are affected for every one girl.

What are the symptoms of Perthes' disease?

Symptoms tend to develop gradually and can include:

    • A limp. This may gradually become worse over a few weeks.

    • Pain in the hip and groin area. Sometimes pain is felt just in the knee or the thigh instead of in the hip - this is called referred pain.

    • Stiffness and a reduced range of movement of the affected hip.

    • In time, the affected leg may become slightly thinner (wasted) because the thigh muscles become thinner as they are not used so much as those in the other leg.

    • The affected leg may look shorter than the good leg.

How is Perthes' disease diagnosed?

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 suggested if the diagnosis is not clear or if a more detailed picture of the hip joint is needed. Possible tests may include: an MRI scan, a bone scan or an arthrogram (an X-ray where dye is injected into the space within a joint). Also, blood tests, or a sample of fluid from the hip 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. Which is the best treatment can depend on the age of the child and the severity of the condition. Treatments may include observation, bed rest and/or crutches, a plaster cast or special leg brace, or surgery. Your doctor will advise on the best treatment for your child.

Observation and physiotherapy

In younger children (under 5 years old), and those with mild disease, Perthes' disease will usually heal well without any specific treatment. These children are treated by observation, often with physiotherapy or home exercises. The home exercises help to keep the hip joint mobile and in a good position in the hip socket. Advice may also include to encourage swimming (to keep the hip joint active in the full range of movements) but to avoid activities that can lead to heavy impact on the hip joint, such as those involving trampolines and bouncy castles. However, any advice will be tailored to your child's needs. Your child will also need regular follow-up with their specialist to check how their femoral head is healing. Regular X-rays of their hips are usually suggested.

Painkillers may also be useful to help relieve pain. Common painkillers suggested are ibuprofen and paracetamol.

Bed rest and/or crutches

This may be needed by some children for a short time if their symptoms are bad.

Plaster casts or a special brace

These may be considered in some cases. The aim is to keep the femoral head well positioned in the hip socket. The cast or brace usually helps to keep the leg slightly abducted (slightly pointing outwards). The special braces are also called orthotic devices. With many of these, the child is able to walk and weight bear, but the braces usually need to be worn for many months. The success of brace treatment is not entirely clear, and many doctors are increasingly advising surgery.


An operation may be considered in some cases, particularly in older children or those more severely affected. Surgery can help to keep the femoral head well positioned whilst it heals, or can improve the shape and function of the femoral head if it has not healed well. There are various options, depending on each child's individual situation. If surgery is being considered, you should discuss the options fully with your child's surgeon.

What is the outcome (prognosis)?

In many cases, the femoral head regrows and remodels back to normal, or near-normal. The hip joint then returns to normal and is able to work as usual. However, it can take two or more years after the condition first starts.

The main concern is that the femoral head does not reform properly. Flattening of the femoral head can occur in some cases and this can lead to a permanent change in the hip joint. This may cause 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. Sometimes, a hip replacement is needed as treatment for arthritis.

Things which may affect outcome include:

    • Age. The younger the child is when Perthes' disease develops, the better the chance of a good outcome. This is because there is longer 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 permanent hip joint problems, such as stiffness and arthritis; there is less time for the hip to remodel before they finish growing.

    • 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 of permanent problems with the hip joint.

Long term irregularity of joint surface leads to degenerative changes /osteoarthritis of hip requiring TOTAL HIP REPLACEMENTFurther help and information

Perthes Association

PO Box 773, Guildford, GU1 1XN

Helpline: 01483 306637 Web:

Aims to help and advise families of children with Perthes' disease.

More about Perthes Disease

Perthes is a condition in children characterized by a temporary loss of blood supply to the hip. Without an adequate blood supply, the rounded head of the femur (the " ball " of the " ball and socket " joint of the hip) dies. The area becomes intensely inflamed and irritated.

Although the term 'disease' is still used, Perthes is really a complex process of stages. Treatment of Perthes may require periods of immobilization or limitations on usual activities. The long-term prognosis is good in most cases. After 18 months to 2 years of treatment, most children return to normal activities without major limitations.

Perthes disease usually is seen in children between 4 years and 10 years of age. It is five times more common in boys than in girls. It was originally described nearly a century ago as a peculiar form of childhood arthritis of the hips.


The child may show signs of limping and may complain of mild pain. The child may have had these symptoms intermittently over a period of weeks or even months. Pain sometimes is caused by muscle spasms that may result from irritation around the hip. Pain may be felt in other parts of the leg, such as the groin, thigh, or knee. When the hip is moved, the pain worsens. Rest often relieves the pain.

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X-rays usually diagnose the condition. The child with Perthes can expect to have several X-rays taken over the course of treatment, which may be two years or longer. The X-rays usually will look worse before gradual improvement is seen.

Perthes disease involves the patient's left hip. The other side is normal.

(Courtesy of Texas Scottish Rite Hospital for Children)


Girls tend to have more extensive involvement; therefore, the expectations (prognosis) are generally poorer than with boys.

For very young children (those 2 to 6 years of age) who show very few changes on their initial X-rays, treatment is usually simply observation.

The older child is treated in order to improve the hip's range of motion.

Nonsurgical Treatment

Anti-inflammatory medications, such as ibuprofen, are used to lessen inflammation of the hip joint or synovium (sleeve of tissue surrounding the hip joint). These medicines are often used for months. The medications will be adjusted or discontinued, depending on the healing stage.

A child with Perthes disease may tend to walk with a limp due to a stiff hip. To help restore hip joint range of motion, the child may be encouraged to walk with crutches and participate in physical therapy. Bed rest in traction may be needed in some cases, however.

With physical therapy, the child will be shown some simple exercises to do until the final stage of healing has occurred.

Hip abduction

The child will lie on his or her back, keeping knees bent and feet flat. With the parent's hands on the child's knees, assist the child as he or she pushes the knees out and as squeezes the knees together.

Hip rotation

With the child on his or her back and with the legs out straight, roll the entire leg inward and outward.

If range of motion becomes limited or if X-rays or MRIs indicate that a progressive deformity is developing, a cast may be used to keep the head of the femur within the acetabulum, or hip socket.

Petrie casts are two long leg casts with a wooden bar that hold the legs spread apart in a position similar to the letter "A." The application of the initial Petrie cast usually is performed in the operating room. During the procedure, the surgeon usually will place a small amount of dye into the hip joint (arthrogram) to aid in evaluating the degree of "flattening" of femoral head. Occasionally, the adductor longus muscle in the groin must be lengthened through a small incision to permit the hip to rotate into a more favorable position.

Petrie casts keep the legs spread far apart in an effort to maintain the hips in the best position for healing.

(Courtesy of Texas Scottish Rite Hospital for Children)

After the cast is removed, usually after four to six weeks, exercises are reinstituted. This treatment may be continued until range of motion is returned or the hip enters the final stage of the healing process.

Surgical Treatment

Surgical treatment re-establishes the proper alignment of the bones of the hip. The head of the femur is placed deep within the socket, or acetabulum. This alignment is kept in place with screws and plates, which will be removed at a later time. In some cases, the socket must also be made deeper because the head of the femur has actually enlarged during the healing process and no longer fits snugly within. After either procedure, the child is often placed in a cast from the chest to the toes for 6 to 8 weeks.After the cast is removed, the child will again participate in physical therapy. Activities will be designed so that the child only partially bears weight on the affected hip. X-rays will show when the final stages of the healing are under way.

An osteotomy to the left hip puts the femoral head in a better position to heal.

(Courtesy of Texas Scottish Rite Hospital for Children)