Osteonecrosis (ON) is a condition where an insufficient supply of blood to the bone results in bone tissue death. With a continued shortage of blood and an ineffective repair process, the bone eventually collapses after tiny breaks (or microfractures) occur. Osteonecrosis is also known as avascular necrosis, aseptic necrosis and ischemic necrosis.
Commonly, ON affects the thigh bone (femur) in the hip area, but can also affect other bones in the body, including the knees, shoulders, ankles and various other joints. (Osteonecrosis of the jaw is a different, unrelated condition.)
Typically, ON will progress, resulting in disability. However, in few cases, it is possible for the bone to heal or be protected from further damage. In these cases there can be few to no symptoms for patients.
Several risk factors are associated with osteonecrosis. These factors are divided into direct and indirect (less common) risk factors. Direct risk factors for ON include:
For indirect risk factors, only a small minority of patients (usually under 10%) will get the disease. These include:
Although these factors are known to be associated with ON, the exact cause is still unknown.
Although not all patients will feel symptoms of ON immediately, most will have pain or a loss of motion in the affected joint.
In many cases, osteonecrosis can be diagnosed with X-rays. However, X-rays cannot always detect the condition. Earlier diagnois of ON is best done with magnetic resonance imaging (MRI). With the close to 100% sensitivity of MRIs, bone scans and biopsies are usually not used for diagnosis.
Treatments for osteonecrosis are based on various factors, including the patient's age, the size of the lesion, its location on the bone that the condition affects, the underlying cause of the problem and the stage of the disease.
Osteonecrosis treatment is meant to ensure bone and joint survival, to prevent additional bone damage and to allow the patient to better use the joint affected. Treatments for ON include:
Other exploratory treatments include medications and combination therapies meant to increase the growth of new bone and blood vessels. Many of these are experimental, but have been proven in studies. Patients need to carefully follow instructions about activity limitations and work with their doctors to make sure that appropriate treatments are used.
Because the exact cause of osteonecrosis (ON) is unknown, there aren't known preventions. There are, however, indirect risk factors that can be controlled:
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This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or healthcare provider. Please consult your healthcare provider for advice about a specific medical condition. This document was last reviewed on: 12/10/2017