Avascular Necrosis

What is Avascular Necrosis (AVN)?

Avascular necrosis (AVN), also known as osteonecrosis, is a debilitating condition characterized by the death of bone tissue due to a lack of blood supply. When AVN primarily affects the femoral head, it can have significant implications for hip joint health and function. In this comprehensive overview, we will explore the causes, risk factors, symptoms, diagnosis, treatment options, and prognosis of avascular necrosis, focusing primarily on its manifestation in the femoral head.

What causes AVN?

Avascular necrosis of the femoral head can occur due to various factors that disrupt the blood supply to the bone tissue. The most common cause is the interruption of blood flow to the femoral head, leading to ischemia and subsequent bone cell death. This interruption may result from trauma, such as hip dislocation or fracture, which can damage blood vessels supplying the femoral head. Additionally, certain medical conditions and risk factors can predispose individuals to AVN, including corticosteroid use, excessive alcohol consumption, blood clotting disorders, radiation therapy, and systemic diseases such as lupus or sickle cell disease. Chronic repetitive stress on the hip joint, such as that experienced by athletes or individuals with certain occupations, may also increase the risk of AVN by compromising blood flow to the femoral head over time.

What are the symptoms of AVN?

The symptoms of avascular necrosis of the femoral head typically develop gradually and may vary depending on the stage and severity of the condition. Early signs may include mild hip pain or discomfort, particularly during weight-bearing activities or movement. As AVN progresses, symptoms may worsen and may include persistent hip pain, limited range of motion, stiffness, and difficulty walking or bearing weight on the affected hip. In advanced stages, the femoral head may collapse, leading to severe pain, joint deformity, and functional impairment.

How is AVN diagnosed?

Diagnosing avascular necrosis of the femoral head often involves a combination of clinical evaluation, imaging studies, and laboratory tests. Physical examination may reveal tenderness over the hip joint, limited range of motion, and signs of hip joint instability. Imaging studies such as X-rays, magnetic resonance imaging (MRI), or computed tomography (CT) scans are used to assess the extent of bone damage, detect changes in the shape or structure of the femoral head, and evaluate the surrounding hip joint structures. Blood tests may be performed to assess for underlying medical conditions or risk factors associated with AVN, such as elevated levels of inflammatory markers or coagulation disorders.