[A review of avascular necrosis, of the hip and beyond].

Avascular necrosis is an ischemic or cytotoxic necrosis of epiphyseal bone, responsible for joint pain, altered life quality and frequently affecting young patients. Avascular necrosis can be unifocal or multifocal, underlining the possibility of a systemic origin. Avascular necrosis involves the femoral head in more than 75% of cases. Although avascular necrosis is irreversible, many risk factors must be sought, including corticosteroid treatment, hypercholesterolemia, sickle cell disease or alcohol abuse. MRI imaging is the main exploration for the diagnostic and staging of the disease, and should be performed in unexplained hip pain in young patients with normal X-rays. In the earlier stages of the disease (stage I and II of the Arlet and Ficat classification), joint surface is preserved, and conservative treatment is recommended. In the more advanced stages (III and IV of the Arlet and Ficat classification), the articular surface collapses and joint arthroplasty is the main treatment. However, there are some recent therapeutic advances, based on mesenchymal stem cells, which may contribute, in the future, to improve the bad functional prognosis of the disease.