Avascular necrosis of the femoral head

Avascular necrosis of the femoral head is an orthopedic condition frequently encountered in small breed dogs. Several synonyms exist to describe this same joint affliction: aseptic necrosis of the femoral head, juvenile osteochondritis or even Legg-Calve-Perthes disease. Regardless of the term used, the problem remains the same and causes your dog pain, which must be remedied as quickly as possible.

Avascular necrosis of the femoral head, as previously mentioned, generally occurs in small dogs. The ``toy`` breeds and terriers are most susceptible to developing this condition which appears before 1 year of age in most cases. Often, the animal is presented in clinic for the acute pain (just began) of a posterior member or a chronic pain (lasting since several weeks or months). Your pet may demonstrate intermittent limping, a reluctance to running, getting up, taking the stairs, jumping and in the worst case, no longer put weight on the affected limb.

During your dogs’ examination, the veterinarian will perform various palpations with the goal of locating the pain in his paw: is it in his hip, knee, ankle etc? He will also check for the presence of muscular atrophy, that is to say a muscle that is smaller which indicates that the animal has not been using his paw adequately for some time. Depending upon the results of the exam, one or several x-rays will be recommended in order to verify the condition of the bones and joints in the area afflicted with pain. The results are available within fifteen to twenty minutes.

Radiographically, the changes typical with this condition are present in the hip joint: a deformation of the femoral head and neck, a change in the opacity ( in color) of the femoral head and neck, light to severe osteoarthritis depending on the case, sometimes even a fracture in the femoral neck. The breed and age of the dog, along with the physical examination and the radiographic lesions are generally sufficient to diagnose the disease.

Why has this problem appeared in your dog?? We do not yet possess all the answers to this question, but a genetic predisposition is strongly suspected in most cases. The problem begins with a vascular disorder: the vessel that nourishes the femoral head and neck ceases to bring blood to this area which causes the death (necrosis) of this area. Following the death of the bone, the degenerative changes in the bone and cartilage remain and the pain begins.

And now, what do we do? It is possible to administer anti-inflammatories to temporarily calm your pet but THE solution is surgical. This operation consists of removing the femoral head and neck to transform

the painful joint into a “pseudo-joint” where the hip muscles replace the function of the femoral head and neck. The surgery can even be done here at the hospital, but you can go consult a veterinary orthopedic surgeon in a reference center if you prefer.

Following the surgical procedure, antibiotics and anti-inflammatories will be prescribed and a physiotherapy protocol established. The physiotherapy is put into place with the goal of a quick return to the normal use of the limb. Complete recovery may take 3 to 6 months and different medical follow ups will need to be done depending upon the progression of your pet.

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