Avascular necrosis, also known as osteonecrosis, is a condition characterized by the death of bone tissue due to a lack of blood supply. This impairment in blood flow can be caused by various factors such as injury, excessive alcohol consumption, corticosteroid use, or certain medical conditions like sickle cell disease. As blood flow decreases, the affected bone becomes weakened, leading to eventual collapse and joint damage. Commonly occurring in the hip, knee, and shoulder joints, avascular necrosis can cause pain, limited mobility, and even disability if left untreated.