It is 100 years since Legg Calve Perthes disease was first identified.

Still little is known about the disease.

The reseach team at Alder Hey Childrens Hospital, Liverpool, UK hope to improve the knowledge of this disease.

E-mail for more info.

More details will be added as the project develops...



What is Perthes Disease?

Perthes disease is a condition that affects children’s hips. The blood supply to the top of the thigh bone (head of femur) is lost and consequently nutrients are unable to reach the hip. We do not know what causes this interruption in blood supply.  The result of the restriction in blood supply is that the head of femur becomes soft and begins to collapse. This causes the child to limp and usually pain. Over a period of a few years the bloods supply returns and the hip reforms.


Why do we treat Perthes Disease?

As the top of the femur bone softens and collapses the joint can be misshapen. Normally the hip joint is made of a ball and socket – diagram below. The benefit of this type of joint is that a smooth round ball in a similar shaped socket allows a great deal of smooth movement within the socket. If the ball becomes misshapen this may restrict some of the movement of the hip joint. In the longer term the difference in shape may cause the onset of early arthritis.

The treatment of Perthes disease is therefore designed to maximise the movement of the hip joint by trying to help the top of the femur bone remain circular in shape.

Treatment of Perthes disease doesn’t actually change the disease itself – i.e. from the start of the process, until the end will always take about 3 years to get better.


How long will my child have pain for?

Pain in Perthes disease tends to follow a waxing and weaning course – that is to say that it is often intermittent and will come and go. The pain tends to be worse in the early stages and gradually improves – though occasionally will ‘flare up’ usually just when you think things are settling down!

Clearly every child is slightly different, and your child’s experience will depend somewhat of their treatment.


What causes Perthes Disease?

We do not know what causes Perthes disease – other than to know that the blood supply to the hip is in someway blocked. There are lots of theories as to the cause but all remain unproven. Doctors in Liverpool, Glasgow and Northern Ireland are all active in seeking to understand about the cause of the disease.


What are the Symptoms of Perthes Disease?

Typically children complain of pain in their groin or knee. This may only come to light after a trivial ‘bang’ or may go on for many months before it is diagnosed. Occasionally the only features of Perthes disease is an abnormal walk or a limp in the child.


Who gets Perthes Disease?

Children who get Perthes disease are generally between 4 and 8 years old – although may be as young as 2 years and as old as 14 years old. Boys tend to get it more than 3 times as often as girls. Typically children who get Perthes disease are usually slightly shorter that their classmates at school – although this is not always the case. Usually just one hip is affected, but about 10 – 15% children will have the involvement of the opposite hip involved within a couple of years of their initial diagnosis.


How is Perthes disease diagnosed?

Doctors will always start by examining the child and asking some questions to try to rule out other potential causes for the pain. Following this the doctor will do some tests, some of which are detailed below:

X-Ray – All children will receive an x-ray of their hips in making the diagnosis. This is quick and painless. In very early disease the x-ray may appear normal. If the x-ray is normal the doctor may chose to ‘watch and wait’ or to get a different test.

Bone Scan – A test that some children may receive in making the diagnosis. A small safe dose of a radioactive chemical is given to the child via a needle into their vein. Special x-rays are then taken that will show if the blood supply to the hip is normal or abnormal. This test is better at identifying very early disease than x-rays.

MR Scan – A Magnetic Resonance scan is a special scan which takes many pictures of the child from different angles using a powerful magnetic field. It is a useful test when a doctor has a particular question about a child’s Perthes disease – though frequently is not necessary. It is a safe test, but requires a patient to lie very still for 10 minutes or so in a loud machine.


What to expect as the treatment progresses?

Throughout the treatment of Perthes Disease doctors will take x-rays to monitor the progression of the disease. They will observe the hip go through 4 stages of change.

Flattening – Initially the top of the femur bone will become slightly flattened and very dense which shows up as white on an x-ray (called sclerosis). This can be a fairly subtle change and difficult to see.

Breaking-up – The head of the hip bone next begins to break up into many pieces (called fragmentation). This can be a concerning feature for relatives but is all part of the healing process.

New Growth – The head begins to reform in patches and can look quite similar to the breaking up phase of the disease (called re-ossification).

Taking shape – This is where the head is reformed in its new shape – preferably as circular as possible (called remodelling).


What tests may be required after the diagnosis is made?

Some times a doctor may chose to do an arthrogram. This is a day-case procedure where the child is put to sleep by general anaesthetic. Some dye is injected into the hip joint and x-rays taken to show the doctor how round the femur bone is, and guide the doctor in their treatment of Perthes. This test is not always required.


When to treat Perthes Disease?

When to treat Perthes disease and how to treat Perthes disease is the cause of much debate in the scientific literature. The purpose of treatment is maintaining the roundness of the femur bone in order to maximise movement and minimise the risk of arthritis in the long-term.

Younger children (below 5 years old) are less likely to need treatment than older children, however sometimes do.

When to start treatment depends upon a combination on the age of your child, the x-ray appearance of the hip joint and the degree of pain and stiffness in the hip. Naturally the expertise and preference of your child’s consultant also plays a significant factor in the treatment.


How to treat Perthes Disease?

As already discussed, how to treat Perthes disease is the cause of much debate in the scientific literature. We therefore present a range of ways that Perthes disease can be treated and urge you to discuss there in more depth with your own consultant, and gain support from the Perthes association.

(1)   “Watchful Waiting”

This is what doctors called ‘conservative treatment’ and is a form of simple observation. It is usually most appropriate in the very young patient who are minimally restricted by Perthes disease. The doctor may suggest trying to restrict your child’s activity – although we accept this is difficult in 3 or 4 year olds! The doctor will simply see you child at intervals to repeat an x-ray of the hips and examine your child to see how much movement they have.

(2)   Splintage

Splintage involves some means of keeping the child’s legs separated with the intention of trying to maintain the collapsed ball of the femur snugly in the round hip socket to encourage it to adopt this shape as it recovers. This may be done with Plaster-of-paris (called a spica plaster, or broomstick plaster), or other designs of splints or callipers. This treatment has generally lost favour over the past few years and in light of scientific research most surgeons will consider earlier operative intervention, although there is still occasionally a role, in some instances, for this form of treatment.

(3)   Operations

There are several forms of operations. All aim to keep the head of the femur bone snugly in the hip socket, so that it reforms in a circular shape. Which operation to do will depend on the age of your child and your surgeon’s preference.

(1)   Femoral Osteotomy – This is typically done in children under 7 or 8 years old. It involves dividing the thigh bone and resetting it using a metal plate and screws. Children may be put in a spica cast following this treatment to give some extra support for a period whilst the bone heals. This typically involves about a week in hospital whilst the child has strong pain killers and gets used to coping in their cast. The metal plate and screws will need to be removed after about 1 – 2 years – this will be a daycase or an overnight procedure.

(2)   Shelf Osteotomy – This is typically done in older children (7 or 8 years and older). It involves creating a ‘porch’ onto the side of the hip socket to keep the hip firmly in place. This is done by repositioning some of the bone from the pelvis adjacent to the socket. This will again require about 1 week in hospital. Children are usually not allowed to put weight through their leg for 6 weeks or so following this period to allow the bone to heal. No screws or plates are routinely used in this procedure – although occasionally may be required.

(3)   Joint Distraction – This is a new technique, still in its infancy, which remains somewhat ‘experimental’. Metal pins are put into both the femur bone and the socket to pull the two apart allowing the femur bone to reform within the socket without it been squashed. This requires a metal bar and some pins on the outside of the child’s skin – which both parent and child will quickly adapt to and usually manage with relative ease. The duration of this treatment will be dependent on a number of factors and your doctor will advise you as to this.

(4)   Medicines

a.       Pain Killers – All doctors will encourage you to give regular pain killers to your child as prescribed by your doctor. Common painkillers that are helpful are regular paracetamol (Calopol), along with an anti-inflammatory as required (usually Ibuprofen or Dicolfenac). Other pain killers may be used if these fail.

b.      Bisphosphonates – These are drugs which are used in adults to treat osteoporosis. They alter the way that bone is behaves, although it is unclear if they will be beneficial in Perthes disease. Their use is therefore experimental in a small number of centres around the world. They often are quite difficult to ‘stomach’, and are made completely useless if taken with milk! We await results to suggest if this drug is beneficial.

(5)   Long Term Effects

Perthes disease is not thought to have any long term ill effects on health – apart from the potential for early hip arthritis. The age at which arthritis develops is dependent upon how circular the hip forms at the end of treatment.

  • Hips which become almost normal on x-rays have a good prognosis and the risk of arthritis in the long term is similar to someone without Perthes disease. Hips which are not circular do have an increased risk of arthritis. The age at which arthritis will develop will depend upon the shape of the head of femur – your doctor will be able to give you an idea as to when they consider arthritis may develop – although you must understand that this is an educated estimation and not a definite value!

  • Leg Length  can be altered by Perthes disease. Typically the Perthes affected leg will be the shorter leg and this is a result of the top of the femur becoming squashed and altered in shape. Surgery such as a varus osteotomy may also shorten the leg further. The difference in the length of the legs is rarely a problem. The lengths of peoples legs are often different and does not cause difficulties – certainly it is known that David Beckham was found to have a difference in the length of his legs when he had his medical examination for Real Madrid – and it doesn’t hold him back too much! If the leg length is more than a 2cm or so the doctor may discuss options to treat this. Treatment is not necessary and depends upon discussions between the child, their parents and the doctors. Ways to treat a difference in leg length:
  • Insoles – The most simple way is to put insoles in the shoes of the child to give them a ‘lift’. These are simple and easy although frequently children do not like wearing them and it can be awkward to find the right shoes.
  • Surgery – This can:

i.                            Make the short leg longer This is a big operation with considerable scaring. It will require the use of a special frame on the outside of the leg, secured with pins going through the bone. This will gradually be altered by about 1mm each day to gradually grow the femur bone. The frame will be present for several months while the bone heals. It is a good option for very large limb length discrepancy but very rarely required in Perthes. 

ii.                    Make the long leg shorter. This is a much simpler operation with less scarring. It involves putting metal plates around the knee in the longer leg around the time of puberty. This slows down the growth in the longer leg and lets the shorter leg catch-up! A potential problem with this operation is that the overall height of the child will be slightly reduced (by as much as is the difference in their leg lengths) – this may not be a concern, however we know that children with Perthes disease are often shorter than their friends and therefore some children do not want this to be done.

We regret we are unable to comment on individual cases of Perthes disease and this information is intended for guidance only.

A useful link in the UK to help you manage your Perthes disease is the Perthes Association:

If you would like to see additional details of this website, or wish to hear more about our research then please contact us.