Avascular necrosis (AVN) is the cellular death of bone components due to interruption of the blood supply. Collapse of bone structure, bone destruction, and loss of joint function may ensue.  AVN affects bones with a terminal blood supply.  The pathophysiology is unclear though theories include vascular occlusion, intravascular coagulation, mechanical stress, and vasculopathy leading to structural damage to walls of veins and arteries. 

     Common locations include the femoral heads, scaphoid, capitate, and talus.

     Predisposing factors include:

• trauma
• chronic corticosteroid use
• alcohol abuse
• chronic pancreatitis
• sickle cell disease or other hemoglobinopathies
• HIV
• osteomyelitis
• malignancy
• renal transplant
• dysbarism (Caisson disease)
• pregnancy