Osteonecrosis or death of bone may occur after an injury or fracture blocks the blood supply to an area of a bone. Studies have suggested that this type of osteonecrosis may develop in about 20 percent of all people who dislocate their hip joint. Minor injuries will not result in osteonecrosis.

Long-term corticosteriod use may also cause osteonecrosis to form. Corticosteriods are used to treat inflammation in diseases, such as rheumatoid arthritis. Doctors are not sure why long-term use of corticosteriod puts people at a higher risk. If you are concerned, talk to your doctor about your particular situation.

Excessive alcohol use is also a common cause of osteonecrosis. Other diseases, such as kidney disease, lupus and blood disorders, are also risk factors for developing osteonecrosis. However, in approximately 30 percent of osteonecrosis cases, the cause is unknown.

Often a person will experience little or no symptoms in the early stages of osteonecrosis. Commonly, the first symptoms felt are pain and aching in the affected joint when it is being used. In hip cases, the pain will most likely be concentrated in the groin area. As the disease progresses, pain may be felt even when the joint is at rest. If it is left untreated and the joint surface collapses, the pain will most likely increase greatly.

Your doctor will be able to use x-rays to diagnose the disease if it has progressed beyond the earliest stages. An x-ray shows the area of the bone that is involved. Beyond x-rays, your doctor may use MRIs (Magnetic Resonance Imaging) to look for tissue changes. If necessary, he or she may also order a CAT scan which is a series of x-rays projected in a three dimensional image.

In order to stop or prevent the breakdown of joints, appropriate treatment is necessary. If the disease has progressed without detection for a long period of time, it will be harder to save the joint. If left untreated, motion will become very difficult and painful. In children, non-weight bearing may prevent collapse and deformity of the bone but it may take a few years.

Walkers and crutches may help when the hip is affected. The use of these assistive devices may stop the progression of the disease while you consider treatment options. In most cases, some type of surgery is necessary. Your doctor will first try to save your original hip but may have to recommend a total hip replacement if you are an adult.

Experts are currently trying out ways to encourage the growth of new bone and blood vessels through medications and combination therapies. At this time, however, most doctors treat osteonecrosis through surgery.

There are several surgical treatment options for osteonecrosis, including:

• Core decompression --This simple procedure works best in cases that are mild and before the collapse of a joint. A hole is created and a thin layer of bone is removed. This reduces pressure within the bone while increasing blood flow to the bone.