Avascular Necrosis: Avascular necrosis (aseptic necrosis or osteonecrosis) is a death of bone, which leads to destruction of the adjacent joint. Causes include fracture, dislocation, steroid medication usage, and excessive alcohol consumption. Risk factors include smoking, pregnancy, radiation therapy and chemotherapy, bone marrow and blood diseases, and the bends. Pain is the main symptom. Treatment involves treating the underlying cause of avascular necrosis and surgery.