Introduction

Arthritis is one of the most common diseases affecting Americans today. However, a related disease is affecting both the young and old alike. Many hip replacements are performed, not for arthritis, but for avascular necrosis (AVN). Each year 10,000 to 20,000 people develop AVN according to the National Institute of Arthritis and Musculoskeletal and Skin Diseases, Health Topics, (January 2001).

AVN occurs when bone tissue dies off resulting in the collapse of the bone. It is caused by the loss of blood to the bone. Areas most commonly affected by the disease are the hips, upper arms, knees, shoulders and ankles. Common names for this disease include avascular necrosis, osteonecrosis, aseptic necrosis and ischemic bone necrosis.

The disease can be caused by:

• Injury: A joint that has been injured, through fracture or dislocation, increases risk of AVN because blood vessels may be damaged. Blood circulation to the bone is disrupted resulting in trauma-related AVN.
• Steroids: Long-term use of corticosteroids (medicines used to treat inflammatory diseases such as rheumatoid arthritis, inflammatory bowel disease and vasculitis), like prednisone, is associated with non-traumatic AVN. These drugs may hamper the body's ability to break down fatty substances resulting in clogged blood vessels, decreasing blood flow to the bone.
• Alcohol: Excessive alcohol use may keep the body from breaking down the fatty substances, which may lead to blocked arteries.

Arthritis and AVN affect both men and women at higher rates as they age. The majority of cases involve people between the ages of 30 and 50 years. However, it can affect people of all ages. Conditions associated with AVN are Gaucher's disease, pancreatitis, radiation treatments, chemotherapy, decompression disease and blood disorders, like sickle cell disease.

Patients in the early stages of avascular necrosis may not display any symptoms. As the disease gradually progresses, patients begin to experience joint pain. If untreated, the bone and surrounding joint surface will eventually collapse, resulting in severe pain. At this point, the pain may limit the patient's range of motion in the joint. Stiffness and limping are also symptoms of AVN. In cases involving the hip, osteoarthritis may develop. The time between the onset of AVN and the loss of joint mobility differs for each patient. This process can take anywhere from several months to over a year.

Finding the appropriate treatment for your symptoms and stage of disease is important to prevent further breakdown of your joints. Some conservative treatments available to achieve this goal include:

• Medicines to alleviate pain and reduce fatty substances that increase with the use of steroids.
• Use crutches or walker to assist in reducing weight bearing to slow damage and promote the healing process.
• Limiting your daily activities may be recommended to reduce stress on the affected joint.
• Range of motion exercises to maintain or improve joint range of motion.
• Electrical Stimulation to stimulate bone growth.

Conservative methods typically work best when avascular necrosis is diagnosed early. When these methods aren't enough to relieve the pain or save the joint from damage, doctors may recommend surgery. There are several types of surgery available to treat AVN with the goal of providing long-term relief. Some of the most common surgeries include:

• Core Decompression to relieve pain by improving blood flow and reducing pressure in the bone. Core decompression surgery removes the inner layer of bone from the affected area. This surgery works best for patients in the early stages of AVN.
  
  
• Osteotomy designed to reduce stress on the joint. Osteotomy reshapes the bone. Patients with advanced AVN get the most benefits from osteotomy.
• Bone grafts to increase blood supply. Grafts transplant healthy bone from one part of the patient to the affected area.
• Arthroplasty/total joint replacement replaces the diseased joint with an implant made of metal, plastic or ceramic. Hip replacement, usually appropriate for patients in the late stages of AVN, is designed to reduce pain and increase patient mobility.

Chronic joint pain from avascular necrosis and arthritis can disrupt your everyday activities. If you may be suffering from AVN, discuss your symptoms and treatment options with your physician. Age, medical history, cause and the stage of the disease will determine the best method of treatment for you.