Avascular

Avascular Necrosis

Avascular necrosis (AVN), also known as osteonecrosis, is a condition that occurs when there is a loss of blood supply to the bone. Without an adequate blood supply, the bone tissue dies and the bone collapses. If this process involves the bones near a joint, it often leads to joint collapse. Avascular necrosis can occur in any bone, but it most commonly affects the ends of long bones such as the femur, humerus, and tibia.

Pathophysiology

Avascular necrosis is caused by the interruption of blood flow to a bone. This can occur due to trauma, such as a fracture or dislocation, or due to non-traumatic factors such as long-term use of high-dose steroids, excessive alcohol consumption, or certain medical conditions like sickle cell disease. The lack of blood flow leads to the death of bone cells and the eventual collapse of the bone structure.

Risk Factors

Several factors can increase the risk of developing avascular necrosis:

• Trauma: Fractures or dislocations can damage blood vessels and interrupt blood supply to the bone.
• Steroid Use: Long-term use of corticosteroids is associated with avascular necrosis.
• Alcohol Consumption: Excessive alcohol intake can lead to fatty deposits in blood vessels, reducing blood flow to bones.
• Medical Conditions: Conditions such as lupus, HIV/AIDS, and pancreatitis can increase the risk.
• Radiation Therapy: Radiation can damage blood vessels and lead to avascular necrosis.

Symptoms

The symptoms of avascular necrosis vary depending on the stage of the disease and the bone affected. Common symptoms include:

• Pain: Initially, pain may occur only when putting weight on the affected joint. As the condition progresses, pain may be present even at rest.
• Limited Range of Motion: As the joint becomes more affected, movement may become limited.
• Joint Collapse: In advanced stages, the joint may collapse, leading to severe pain and disability.

Diagnosis

Diagnosis of avascular necrosis typically involves a combination of clinical evaluation and imaging studies. Common diagnostic tools include:

• X-rays: Can show changes in bone structure in advanced stages.
• MRI: More sensitive than X-rays and can detect early changes in bone tissue.
• CT Scan: Provides detailed images of bone structure.
• Bone Scan: Can show decreased blood flow to the affected area.

Treatment

Treatment for avascular necrosis aims to improve the function of the affected joint, relieve pain, and prevent further bone damage. Options include:

• Medications: Pain relievers and anti-inflammatory drugs.
• Physical Therapy: Exercises to maintain joint mobility.
• Surgery: Options include core decompression, bone grafts, or joint replacement.

Prognosis

The prognosis for avascular necrosis depends on the stage at which it is diagnosed and the effectiveness of the treatment. Early diagnosis and treatment can improve outcomes and prevent joint collapse.

Also see

• Osteoporosis
• Bone Fracture
• Joint Replacement
• Sickle Cell Disease