"A-" means without, "vascular" means blood vessel, therefore avascular
necrosis means that the bone has died because it lost its blood
supply.
Lupus patients who have been taking steroids for a long period
can develop avascular necrosis.
This is caused by the change in blood flow to part of a bone, which
results in the death of that area of bone.
The body tries to repair this area of dead bone, but the bone weakens
& part of the bone surface may collapse.
The main symptoms are pain when the joint is being moved or bearing
weight, later, the pain can also be felt when resting.
The most commonly affected areas, are the knees, hips & shoulders.
There is no treatment for the condition, but joint replacement
is an option.