Avascular necrosis is the death of bone tissue due to a lack of blood supply. Also called osteonecrosis, avascular necrosis can lead to tiny breaks in the bone and the bone's eventual collapse. The blood flow to a section of bone can be interrupted if the bone is fractured or the joint becomes dislocated. Avascular necrosis typically causes no symptoms; however, as the disease progresses it becomes painful.
At first, you may experience pain when you put pressure on the affected bone. Then, pain may become more constant. If the disease progresses and the bone and surrounding joint collapse, you may experience severe pain that interferes with your ability to use your joint. The time between the first symptoms and collapse of the bone may range from several months to more than a year. If avascular necrosis is caught early, treatment may involve taking medications to relieve pain or limiting the use of the affected area.
If your hip, knee, or ankle is affected, crutches may be necessary to take weight off the damaged joint. Your doctor may also recommend range of motion exercises to help keep the affected joint mobile. It is also associated with Osteoarthritis and Knee injuries. "Globally, osteoarthritis is the commonest joint disorder, and the WHO estimated that as much as 40% of the people over the age of 70 years suffer from osteoarthritis of the knee.
It accounts for 14.8 million disability adjusted life years (DALYs) lost, with 80% percent of those afflicted having some degree of limitation of movement and 25% being unable to perform the major activities of daily living. As the incidence and prevalence of osteoarthritis increase with age, the DALYs lost due to this disease are expected to increase by 40% by 2030. In Singapore, 17,000 DALYs lost are attributable to osteoarthritis. According to a statistical analysis there are Extrapolated Incidence of Avascular Necrosis is 160 in Singapore."