Avascular Necrosis

Avascular necrosis is a disease resulting from the temporary or permanent loss of blood supply to the bone. Without blood, bone tissue dies and causes the bone to collapse. If the disease affects the bones near a joint, it often leads to collapse of the joint surface.

Etiology

Avascular necrosis can be caused by injury (trauma-related avascular necrosis or joint dislocation) or by certain risk factors (non-traumatic avascular necrosis). The latter causes can include:

• Some medications (steroids)
  
  
• Blood coagulation disorders
  
  
• Excessive alcohol use

Increased pressure within the bone, which is also associated with avascular necrosis, causes the blood vessels to narrow, making it hard for them to deliver enough blood to the bone cells. 

Symptoms

In the early stages of avascular neurosis, a person may not have any symptoms. As the disease progresses, however, most people experience joint pain - at first only when putting weight on the affected joint, and then even when resting. Pain usually develops gradually and may be mild or severe. If avascular necrosis progresses and the bone and surrounding joint surface collapse, pain may develop or increase dramatically. Pain may be severe enough to limit a person's range of motion in the affected joint 

Diagnosis

After giving a complete physical examination and asking about a patient's medical history, a doctor may use one or more imaging techniques to diagnose vascular necrosis. As with many other diseases, early diagnosis increases the chances of treatment success. Tests to measure pressure inside a bone may be used when a doctor strongly suspects a patient has vascular necrosis, even though X-rays, bone scans, and MRIs may be normal. These tests are very sensitive and can detect increased pressure within the bone, but they require surgery.

Treatment 

This condition requires evaluation and management by a medical professional and may include:

• Medicines to reduce fatty substances (lipids), which increase with corticosteroid treatment, or to reduce blood clotting if clotting disorders are present 
  
  
• Nonsteroidal anti-inflammatory drugs to reduce pain
  
  
• Weight bearing reduction to the affected joint by limiting activities or by using crutches; in some cases this can slow the damage and allow natural healing
  
  
• Range of motion exercises  to maintain or improve joint range of motion
  
  
• Electrical stimulation to induce bone growth

• Core decompression - Removal of the inner layer of the bone, which reduces pressure within the bone, increases blood flow to the bone, and allows more blood vessels to form
  
  
• Osteotomy - Reshapes the bone to reduce stress on the affected area
  
  
• Bone graft - Transplant healthy bone from one part to the diseased area to support a joint after core decompression
  
  
• Arthroplasty/total joint replacement - Total joint replacement with artificial parts in late-stage vascular necrosis and when the joint is destroyed.