This is a condition in which the bone of the femoral head becomes weakened and sometimes collapses. It is thought to be due to an interruption of the blood supply to the bone, but it is not known why this happens. A similar problem can occur in bones elsewhere in the body, but it can be particularly devastating in the hip because of the pain and disability that it can cause. AVN seems to be part of a family of disorders that may include bone marrow oedema syndrome, transient osteoporosis of the hip, and idiopathic capsulitis (a condition rather like a 'frozen shoulder').
How can AVN treated?
When symptoms first begin, pain can be excruciating. The abnormality may only show up on MRI scanning and at this stage it is important to distinguish between avascular necrosis and other causes of bone marrow oedema. Many patients will benefit from an extended period on crutches, and some may benefit from drug treatments to improve blood flow or reduce bone damage. In a few patients, surgery may be appropriate and this may involve arthroscopically guided drilling of the femoral head, vascularised grafting of the damaged area, or reconstruction of the bone and its overlying cartilage.