History of Osteonecrosis

About 20,000 new people are diagnosed with osteonecrosis (ON) every year. It is characterized by the death and collapse of a large portion of the bone. Though this can be painful and severely affect joints like the hip and shoulder, it is not life-threatening.

Definition

• Osteonecrosis ("osteo"- bone, "necrosis" - death) is a condition in which the bone dies as a result of blood loss. Osteonecrosis also has been called ischemic necrosis of the bone and avascular necrosis (AVN). Some doctors still refer to it by the latter acronym because is simple to write and recognize.

Types

• ON can either be post-traumatic or non-traumatic. Post-traumatic ON occurs after bone fractures and dislocations. The trauma weakens the structure of the bone and the local blood vessels and can make the patient susceptible to ON. Non-traumatic cases of ON have no beginning trauma and are difficult to detect.
  Osteonecrosis of the hip is the most common form, followed by ON of the shoulder. For every 10 cases of ON of the hip, there is one case of ON of the shoulder. Knee and ankle ON occur even less frequently.

Causes

• It is important to remember that bones are living tissue and thus need the circulation of blood to survive. When they lose this blood supply, bones weaken and collapse. The effects felt by the patient can range from mild pain to an inability to walk.
  The risk factors of non-traumatic ON are further broken down into two groupings: definite and probable. Patients with definite factors like major fractures, dislocations, sickle cell disease, exposure to chemotherapy and arterial disease face a high level of risk of ON. Probable causes include steroid and alcohol abuse, blood-clotting disorder, lipid disturbances and kidney disease. Many researchers believe that these conditions play a part in ON, but their presence in a patient's history do not make them a certain cause of ON.

Treatment

• Treatment of ON can be broken down into two groups: pharmaceutical and surgical.
  Research into pharmaceutical treatments of ON have so far been inconclusive. There are, however, some hypotheses that are being pursued. Lipid-lowering agents are medications that aim to decrease the amount of lipids (fats) in the bone. Some studies are also looking at using hypertensive medication, drugs used to lower blood pressure.
  Surgical treatments vary. A common procedure includes removing a piece of the bone core to relieve pressure in the affected area. Surgeons might also take a bone graft from another part of the body (like the fibula). Another method is placing a metal cap on the head of the femur bone to replace damaged bone.

Warnings

• When you feel joint pain, talk to your doctor. It might not be osteonecrosis, but early treatment has the best prospect for success.
  If you receive a diagnosis of ON, play an active role in your recovery. Learn about your condition and ask questions.