Perthes' disease is a condition that affects children, particularly boys, between the ages of 4 and 10 years old. The condition is characterised by degeneration of the hip joint, as a result of limited blood supply. While the joint can heal, the condition may lead to osteoarthritis and joint problems later in life.
Also referred to as Legg-Calve-Perthes disease in honour of the doctors who identified the condition. Also called avascular necrosis.
What is Perthes disease?
It is a condition characterised by degeneration of the ball and socket joint of the hip. The head of the femur softens and dies as a result of loss of blood supply to the area. As the dying cells are replaced by new bone, the joint becomes less stable. Depending on treatment, rehabilitation and management of the condition, the patient may have an increased risk of osteoarthritis in the hip later in life.
What causes Perthes' disease?
While the mechanism for bone degeneration is known to be loss of blood supply to the hip joint, the precise cause of the blood loss is not known. Several theories exist, including one that abnormal blood clotting blocks the small arteries to the joint. Another is that the main artery to the femoral head closes too early, perhaps as a result of injury or malnutrition. Genetics may be involved, since the condition is five times more likely to affect boys - this link has not been proven, however.
What are the symptoms of Perthes' disease?
Initially, mild pain and limping are the symptoms, experienced over a period of months. The muscles around the hip joint may spasm to increase the pain. The pain is worsened when the hip is moved. Occasionally, the pain may be felt in the knee joint or the groin area.
How is Perthes' disease diagnosed?
The pain is an indicator of the condition. Together with history, a physical examination of movements causing pain help to establish a diagnosis. X-rays are however the primary method for confirming diagnosis. An MRI-scan is not necessary, but can establish the degree of deformity.
How is Perthes' disease treated?
Treatment is based around avoiding degenerative arthritis later in life. There is no cure for Perthes' disease and so the focus of treatment is management, and allowing the femoral head to grow normally and without deformity. This may involve the prescription of pain medication, but primarily focuses on removing pressure on the hip joint, by means of several things: the use of crutches when walking, bed rest, and traction in some cases. Anti-inflammatory medications are used to reduce the inflammation around the bone. In time, physical exercises can be introduced to develop strength in the affected area. In some cases, especially with older children, surgery is an option to realign the hip joint.
What is the prognosis?
Prognosis depends on the severity of the condition, the timing and quality of treatment and rehabilitation. In younger children, where the condition is identified early, the prognosis is relatively good, since there is time for the bone to heal and grow normally. However, with age, the prognosis worsens, and the risk of developing osteoarthritis later in life increases.
When to call your doctor
Children often do not actively report the pain symptoms of Perthes' disease, but will show a pronounced limp, which may last for weeks. If no obvious cause of the limp (such as an acute injury) can be established, physical examination would be required to identify a cause.
How can Perthes' disease be prevented?
Since the cause of the loss of blood flow is not conclusively known, prevention is not known either. There is evidence that malnutrition can lead to Perthes disease, suggesting that adequate nutritional practices may prevent the condition.