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.
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.
According to some studies, performed in Switzerland, To investigate the prevalence of osteoarthritis (OA) of the knee in elderly subjects, we studied the Framingham Heart Study cohort, a population-based group. During the eighteenth biennial examination, we evaluated the cohort members for OA of the knee by use of medical history, physical examination, and anteroposterior (standing) radiograph of the knees. Radiographs were obtained on 1,424 of the 1,805 subjects (79%). Their ages ranged from 63-94 years (mean 73). Radiographs were read by a radiologist who specializes in bone and joint radiology, and were graded 0-4 according to the scale described by Kellgren and Lawrence. OA was defined as grade 2 changes (definite osteophytes), or higher, in either knee.
Radiographic evidence of OA increased with age, from 27% in subjects younger than age 70, to 44% in subjects age 80 or older. There was a slightly higher prevalence of radiographic changes of OA in women than in men (34% versus 31%); however, there was a significantly higher proportion of women with symptomatic disease (11% of all women versus 7% of all men; P = 0.003). The age-associated increase in OA was almost entirely the result of the marked age-associated increase in the incidence of OA in the women studied. This study extends current knowledge about OA of the knee to include elderly subjects, and shows that the prevalence of knee OA increases with age throughout the elderly years. According to a statistical analysis there are Extrapolated Incidence of Avascular Necrosis is 273 in Switzerland.