Avascular Necrosis

Avascular necrosis is a progressive condition, a disease that worsens over time. It occurs when blood flow to a bone is disrupted. Since bone tissue is living and requires a continuous supply of oxygen and nutrients, any prolonged interruption in circulation can cause bone cells to die. As the affected bone weakens, it may collapse, leading to joint deterioration and arthritis.

The hip joint is the most commonly affected site because of its unique vascular structure. The femoral head, which forms the ball of the hip joint, relies on small blood vessels that can be easily compromised due to trauma, disease, or other underlying conditions.

Avascular necrosis often develops gradually, and symptoms may not be noticeable in the early stages. As the condition progresses, patients may experience:

• Joint pain – The most common symptom is pain in the affected joint, which may start as mild discomfort and gradually worsens. Hip avascular necrosis typically presents with pain in the groin, thigh, or buttock.
• Stiffness and limited range of motion – As the hip femoral head bone deteriorates, joint stiffness and restricted movement become more prominent, making activities like walking, standing, or sitting for prolonged periods difficult.
• Pain with weight-bearing activities – Many patients report increased pain while walking or putting weight on the affected limb.
• Persistent discomfort at rest – In advanced cases, pain may persist even when resting or lying down.
• Joint instability or collapse – As the bone weakens, the joint may become unstable, leading to a risk of collapse and severe arthritis.

Early diagnosis of avascular necrosis is crucial to prevent further joint damage. Hip surgeon Dr. Danial Kaplan will evaluate your symptoms, review your medical history and perform a comprehensive examination. The diagnostic process will include:

Dr. Kaplan will perform a physical exam including joint mobility, range of motion, and areas of tenderness. He will order imaging studies including X-rays, an MRI, and possibly a CT scan. He may also order a bone scan to help identify areas of reduced blood flow which can indicate avascular necrosis. Blood tests can help identify underlying medical conditions that contribute to AVN, such as autoimmune diseases or clotting disorders.

Avascular necrosis occurs when blood flow to the bone is compromised. There are several possible causes and risk factors:

Trauma-Related Causes

• Fractures and Dislocations – A significant fracture or joint dislocation can damage the blood vessels supplying the bone, leading to AVN.
• Repetitive Stress or Overuse – High-impact activities or repetitive joint stress, particularly in athletes, may contribute to AVN over time.

Non-Traumatic Causes

• Corticosteroid Use – Long-term or high-dose corticosteroid use (such as prednisone) is a leading risk factor for AVN. While the exact mechanism is unclear, steroids are believed to increase fat deposits in blood vessels, restricting circulation to the bone.
• Excessive Alcohol Consumption – Heavy alcohol use can lead to fatty deposits in blood vessels, reducing blood flow to bones and increasing the risk of AVN.
• Medical Conditions – Certain health conditions, such as sickle cell disease, lupus, and blood clotting disorders, can impair circulation and contribute to AVN development.
• Radiation and Chemotherapy – Treatments for cancer, including radiation and chemotherapy, may weaken bone structure and disrupt blood supply.
• Pancreatitis – Chronic inflammation of the pancreas has been linked to AVN, possibly due to its effects on lipid metabolism and blood flow.
• Autoimmune Diseases – Conditions like rheumatoid arthritis and lupus can cause systemic inflammation, affecting blood supply to bones. 

In some cases, avascular necrosis develops without a clear cause. This is known as idiopathic avascular necrosis. Genetic factors and metabolic imbalances may play a role.

Avascular necrosis can affect anyone, but certain groups are more at risk:

• Athletes and active individuals – High-impact sports and repetitive joint stress increase susceptibility to avascular necrosis, especially in weight-bearing joints.
• Individuals with chronic medical conditions – Patients with autoimmune disorders, sickle cell disease, or metabolic disorders have an increased likelihood of developing avascular necrosis.
• Patients on long-term use of corticosteroids or chemotherapy can compromise blood flow to bones.
• Heavy alcohol users – Chronic alcohol consumption is a significant risk factor.
• Some organ transplant patients develop AVN due to immunosuppressive medications that affect blood flow.