Avascular Necrosis is the death of the bone or necrosis which results from a situation where there is a problem with the vascular system. Avascular Necrosis is the death of bone tissue because of poor blood supply or avascularity- lack of blood supply.

This disease predominantly affects the long bones, particularly the femur which joins at the hip. The other joints that can be affected are the head of the humerus (Shoulder), sometimes the tibia (Knees), and sometimes even the bones in the hands and feet and the jaw bone or (Mandible).

The exact cause of Avascular Necrosis is still not fully established. However, several risk factors have been identified. One of the most common reasons seems to be the blockage in the blood supply caused by globules of fat called lipid embolism. Other factors are injuries affecting the blood vessels and other metabolic and blood-related diseases.

The lipid embolism blocking the small blood vessels supplying blood to the bones, which is the most common cause is most commonly a result of the administration of steroids.

The other common causes of precipitation of Avascular Necrosis are chronic alcohol consumption and high circulating fat levels (Dyslipidaemia). Of late, COVID infection has also been implicated as a leading cause of AVN. Patients have administrated steroids at a high dose over a period of time, in the case of severe autoimmune diseases or in the cases where people are suffering from asthma or other immune-related conditions requiring immune suppression. Some of the other causes are not yet fully known and these are cases of Avascular Necrosis of unknown etiology.