Osteonecrosis

Osteonecrosis is a disease caused by reduced blood flow to bones in the joints. With too little blood, the bone starts to die and may break down.

Osteonecrosis is also known as:

• Avascular necrosis
• Aseptic necrosis
• Ischemic necrosis.

Osteonecrosis is most often found in the hips, knees, shoulders, and ankles. You may have osteonecrosis in one or more bones.

According to the American Academy of Orthopaedic Surgeons, 10,000 to 20,000 people develop osteonecrosis each year, and most of them are between 20 and 50 years of age.

Symptoms and Diagnosis

When osteonecrosis first begins, you may not have any symptoms. You may start to feel pain when you put weight on a joint with osteonecrosis. As the disease gets worse, you may have more pain and the joint may hurt even when you rest. Pain may be mild or severe.

If the bone and joint start to break down, you may have severe pain and not be able to use the joint. For instance, if you have osteonecrosis in the hip, you may not be able to walk. The time from the start of symptoms to losing use of the joint can range from months to more than a year.

To diagnose osteonecrosis, your doctor will take your medical history and do a physical exam. Your doctor may then order one or more tests to see which bones are affected:

• X ray
• Magnetic resonance imaging (MRI)
• Computed tomography (CT) scan
• Bone scan
• Bone biopsy
• Measure of the pressure inside the bone.

Causes

Osteonecrosis is caused when the blood flow to the bone decreases, but why this happens is not always clear. Some known causes of osteonecrosis are:

• Steroid medications
• Alcohol use
• Injury
• Increased pressure inside the bone.

Risk factors for osteonecrosis are:

• Radiation treatment
• Chemotherapy
• Kidney and other organ transplants.

Osteonecrosis is more common in people with illnesses such as:

• Cancer
• Lupus
• HIV
• Gaucher’s disease
• Caisson disease
• Gout
• Vasculitis
• Osteoarthritis
• Osteoporosis
• Blood disorders such as sickle cell disease.

Osteonecrosis can also affect people for no known reason, even if they have no other health problems.

Reference:

National Institute of Arthritis and Musculoskeletal and Skin Diseases, USA.