Necrosis of the Femoral Head

This condition is also called Legg-Calvé Perthes disease, Legg-Perthes disease or sometimes aseptic necrosis of the femoral head.

What is the condition?

The hip is a ball and socket joint. Necrosis or death of the femoral head means that the ball part of the joint is no longer properly functioning. This is because during the growing phase the bone of the femoral head becomes deprived of its blood supply and dies. The body then attempts to heal the defect and a deformed femoral head, which does not fit the socket, is the result. This in turn stimulates arthritic change so that there is progressive unilateral or bilateral hind leg lameness, pain and restricted joint movement in a dog sometimes as young as five months.

What causes the condition?

We know that it is a hereditary condition of small breed juvenile dogs, particularly terriers. It is associated with an autosomal recessive gene.

How is it diagnosed?

Usually slowly increasing lameness and disinclination to bear weight are the main clinical signs. Usually one hind leg is affected before the other but occasionally small dogs are presented with the condition affecting both femoral heads simultaneously. On clinical examination there is usually restricted joint movement, lack of muscle and apparent limb shortening. The owners often speak of a change in temperament. A sweet tempered Toy Poodle becoming increasingly snappy is an example. Radiography will confirm the diagnosis.

What is the treatment?

The treatment of choice is excision arthroplasty of the femoral head and neck. This means that the whole of the diseased ball of the ball and socket joint is removed. Because the condition affects small, young dogs, especially terrier types, it is found to be unnecessary to replace the hip joint. This is necessary in larger, heavier dogs for example hip replacement is one of the treatments available for those suffering from hip dysplasia. Post operatively dogs suffering from Perthes disease will usually be walking well in about four to six weeks.

What happens to the joint if part of the hip is removed?

Healing involves the laying down of fibrous tissue and in a very short time in a young dog a false joint is created. Within months, in the majority of cases, it will be hard to tell that the joint has been operated.

Do complications occur?

Occasionally return of function does not occur as anticipated or the dog starts to use the limb and then once more shows signs of increasing lameness. This however is relatively uncommon but sometimes does involve further surgery.

Will I be able to breed from my dog?

In view of the hereditary implications veterinary advice must be that you should not breed from an affected animal.

Is there anything else I should know?

In a proportion of cases of Legg-Perthes disease a slipping knee cap (medial luxation of the patella) can occur and this can result in subsequent lameness. Again this is a relative uncommon complication.