PERTHES DISEASE GENERAL INFORMATION

What is this disease?

Perthes' Disease is the name applied to a condition which affects the upper end, or head, of the thigh bone, where it enters into the formation of the hip joint. In this condition the growing part of the head goes through a series of changes, in which it softens, may become flattened, and then gradually re-forms.

How is Perthes' diagnosed?

Early diagnosis greatly improves the rate of recovery. Delayed treatment or diagnosis after the age of 8 may affect the outlook. Consult the doctor immediately the condition is suspected, or if the child limps for more than 48 hours. An x-ray must be taken; Perthes' cannot be diagnosed by a blood test.

How long will it last?

The condition runs a slow course. As you have probably already noted in the case of your own child, the onset of symptoms - limp, pain in hip or knee - develops slowly and insidiously. There may be no pain at all. It must be remembered that every case is different. So, too, the recovery phase takes a long time - rarely less than 18 months; often 2 years or even longer. This may seem an unbearably long period of disability, but if considered in relationship to your child's total life span, it is not long.

What causes Perthes' Disease?

The changes of the disease are due to the fact that the growing end (epiphysis) of the thigh bone (femur), has its blood supply cut off. This results in the softening of part or all of the bony 'nucleus' of the epiphysis. The smooth cartilage ('gristle') covering this bone remains unchanged as it is feed by the joint fluid, so you don't have to worry about the shape of the bone in x-rays.

The cause of the interruption of blood supply is not known. The condition usually develops between the ages of about 4 and 10 years, when the stage of development of the epiphysis renders it especially liable to such interruption. It occurs much more commonly in boys than in girls. When the process develops there is often a first pain in hip or knee, and some muscle spasm associated with limping.

The affected part of the bone looks denser in the x-rays. Over a period of time (measured in months), this bone is gradually and irregularly absorbed in the body, giving rise to the fragmented or broken-up appearance in the x-ray.

Sometimes the head becomes swollen beyond its normal size and if this occurs, it may become squashed out of its normal smoothly rounded shape. In these cases, the head does not return to its normal shape but the new bone grows into a deformed shape which would then remain for the rest of the child's life and may be a source of disability in the hip. This is rarely the case.

What of the other hip?

The opposite hip may become affected, either at the same time or later, in about one case in eight. If your child complains of an ache in the good leg, tell the doctor.

What is the treatment of Perthes' Disease?

Many patients with Perthes' Disease merely require observation and x-ray from time to time. Often a period of bedrest with no physical activity is necessary to ease severe pain and limping.

Futher treatment may include:

• traction to the involved leg
• braces to hold the legs apart
• plaster cast for protection and support
• physiotherapy, including swimming
• use of a wheelchair to prevent weight-bearing
• surgery to insert metal plates and screws and to change the angle of the thigh bone.

NB: Surgery in only necessary in 2% of all cases.

What of my child's schooling?

Your child can and should attend school as normal, but some restriction of physical activities may be necessary.

What of my child's future?

Perthes' is a self-limiting disease. It will pass through the stages described above and finally heal. This may take a long time, but in the great majority, the child will have a painless hip with a good range of movement. A few will be left with some stiffness and some pain in the hip. Because the precise cause is unknown, results cannot always be predicted. The outlook is poorer where treatment is delayed or if the disease occurs after the age of 8. But early detection and adherence to treatment greatly improves the outlook.