What is Perthes disease?
Perthes disease (also known as Legg-Calve-Perthes disease, or Calve Perthes disease, or avascular necrosis) is a childhood disorder which affects the head of the femur ( the ball of the ball and socket joint of the hip). In Perthes disease the blood supply to the growth plate of the bone at the end of the femur (called the epiphysis) becomes inadequate. As a result the bone softens and breaks down (a process called necrosis). It is not clear why this blood vessel problem occurs in the femoral head. It is not due to injury, or to a general blood vessel problem. A child with Perthes’ disease is usually otherwise well. Over several months the blood vessels regrow, and the blood supply returns to the ‘dead’ bone tissue. New bone tissue is then laid down and the femoral head regrows and remodels over several years. This is similar to how bone reforms and remodels after any ‘normal’ fracture or break to a bone, but takes longer. Perthes disease is not really as a disease, but that was the name given to it when it was first discovered.
What are the symptoms?
The condition usually begins with hip or groin pain, or a limp. Sometimes knee pain is the first symptom. The pain persists and there may be wasting of the muscles in the upper thigh, shortening of the leg and stiffness of the hip, which can restrict movement and cause problems with walking. When Perthes disease has been present for a long time the affected leg may appear to be shorter and thinner than the unaffected one. A GP will normally refer a child with suspected Perthes’ disease to a specialist. Tests which may be done include:bones2 X-rays of the hip. X-ray pictures can show a femoral head which is broken or damaged. A typical appearance is a ‘flattened’ femoral head when it should normally look rounded in the hip socket. However, the X-ray can be normal in the early stages of the disease before the ‘softened’ bone breaks. An X-ray every few months can show the progress of the breakdown, and then healing as new fresh bone is made and gradually ‘remodelled’. Bone scan. This may be done to confirm Perthes’ disease in the early stages when the X-ray picture is normal, but symptoms suggest that Perthes’ disease is the problem. An MRI scan or other tests are sometimes used to asses the extent of the damage.
What happens next?
Until recently most children with Perthes’ disease were treated with a plaster cast or 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. So, in some cases a specialist may simply review the child every now and then to check that the femoral head remains in the right place as it heals. 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. 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 remodels. Treatments advised can depend 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.
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). The child can walk and weight bear in these devices but they may need to be worn for many months. At the very least, physical acivity may be severely restricted if the hip condition is itself severe. In contrast, some specialists will allow full activity, although some sports may be inappropriate. While there is limited evidence of sport and activity affecting the course of the condition, there can remain the possibility of on-going damage to a weakened hip bone if it is not well contained within its joint; the effect on the entire family of a diagnosis may lead to anxiety and this should be supported by the team treating you.
Q. Why are there so many different sources of information about Perthes’ disease that give different answers?
A. This is because Perthes’ disease is a condition where there are fewer certainties than in many other hip conditions in childhood. Even the greatest experts in the world have uncertainties about what to do with individual patients with Perthes’ disease. Information sites on Perthes’ disease tend to range from those that do not recommend any active treatment to those that might give you the impression that all children need active treatment and a great proportion of children need operations. Many of these latter information sources are from centres where by attracting many of the more difficult to treat cases, it is easy to have the impression that a high proportion of children need operations. There are therapeutic nihilists – practitioners who do not believe that any treatment in Perthes’ disease is effective and therefore that no active treatment should be offered. Whilst it is true that in at least three quarters of children who have Perthes’ disease, there is no role for surgical treatment, there is a small minority that vary as a proportion of any doctor’s practice, who will probably benefit from more active intervention, such as surgery.
Q. Why are there so many different operations?
A. Surgeons operative practice is, to an extent, dictated by who trained them, who their trainer was trained by and so on. They also tend to do operations they are familiar with and relatively few surgeons are, in general, developing new operations for any condition. Another point to bear in mind is that in different phases of the disease, different operations can have a role. For instance, in relatively early stages of the disease, varus femoral osteotomy and Salter pelvic osteotomy have a role. In intermediate stages of the disease, triple pelvic osteotomy can have a role. In later stages of the disease in childhood, valgus femoral osteotomy can have a role. Perthes’ disease is such a variable condition that it would be difficult to find two children in any hundred of comparable age, size, weight, disease severity and disease extent and this has confounded many experts’ efforts to standardise treatment and, indeed, to perform properly controlled trials. Please remember that your child’s own specialist is the person to ask about the activities which he or she regards as appropriate for your child. Children under the age of 5 have a very good chance of a full recovery, but it is known that the older the child the less optimistic the prognosis.