Osteonecrosis.

Last updated Monday, December 27, 2004

Figure 1 - Normal hip joint versus hip joint with osteonecrosis

About

Basics of osteonecrosis

Prevention

As the saying goes, "prevention is the best medicine."

If you are taking high doses of steroids for any reason, it is important for you to continue to see your doctor on a regular basis. Proper monitoring of your steroid treatment is essential to reduce the chances of undesirable side effects such as osteonecrosis. If you drink alcohol to excess, you should decrease or stop your intake. These measures may decrease the chance of getting the condition, but there is no guarantee.

Symptoms

The primary symptom of osteonecrosis is pain.

Other symptoms of osteonecrosis include limitation of motion, joint stiffness, and muscle spasms.

Pain

Pain can start out slowly as mild pain, especially when walking, standing, or lifting. The pain commonly becomes worse after standing, walking, or doing some other activity in which gravity exerts pressure on your bones (such activities are called weight-bearing activities). In later stages, the pain can occur even when you are resting, and sometimes, it may awaken you from sleep.

Limitation of motion

In the early stages, joint motion is not affected. However, due to pain, it may become difficult to move the affected joint. Eventually, if the bone collapses, the cartilage is injured and arthritis will result. Joint motion can then become impossible, or at best, difficult.

Muscles and joints

Muscles contract and tighten when there is pain in the area near them. These contractions are called muscle spasms. Spasms can cause more pain. Joint stiffness can occur due to the muscle spasms, pain, and limitation of motion.

Progression

Causes

For unknown reasons, the blood flow slowly decreases over time, creating pressure within the bone. Eventually, the bone begins to develop tiny breaks and collapse (see figure 1).

An injury such as a fracture (broken bone) or a hip dislocation can cause a loss of blood supply to the area. Alcoholism, an infection, sickle cell disease, pancreatitis (inflammation of the pancreas), or an organ transplant may cause a loss of blood supply to the area.

Incidence and risk factors

The following groups of people are most at risk for developing this condition:

• People who have a rheumatic disease such as rheumatoid arthritis or systemic lupus erythematosus;
• People who are taking high doses of steroids (cortisone-like drugs);
• Alcoholics;
• Professional scuba divers who have the bends (a condition brought on by the rapid reduction of air pressure).

Osteonecrosis of the hip occurs most often between the ages of 30 and 50, and is slightly more frequent in men than in women. Osteonecrosis of the knee occurs most often between the ages of 50 and 60, or much earlier if other risk factors are present. Osteonecrosis of the knee occurs three to four times more often in women than in men. Osteonecrosis often involves more than one joint at a time.

Diagnosis

Early diagnosis of osteonecrosis is important in order to lessen damage to bone.

In its earliest stages, the condition can be difficult to diagnose. A careful history and physical examination may provide evidence that the affected joint causes pain on movement. Diagnosis at this stage is best made by X-rays and some of the new computerized scanning procedures.

As the condition progresses, the death of bone often leads to changes within the bone and nearby joints so that a routine radiograph shows these changes. All too often, permanent damage has already developed by this point.

Treatment

Aspirin and the newer nonsteroidal anti-inflammatory drugs (NSAIDs) can help relieve the pain of osteonecrosis. Heating pads, warm baths, and an electric blanket can relieve muscle spasms and pain. These measures may provide some relief, but do not change the underlying process.

In the early stages of osteonecrosis, you must avoid stress to the affected area. If your hips or knees are involved, reduce standing and walking as much as possible. While sitting, elevate your legs. Your doctor will probably order crutches or a cane to help take some of the weight off the affected joint or joints. He or she may advise that you avoid or reduce weight-bearing activities such as unprotected walking, standing, and carrying.

Keep in mind that it is up to you to keep your doctor informed of any increase in pain or decrease in mobility. This way, he or she can work with you to keep you as comfortable and functional as possible.

In later stages, if the area of bone has been severely damaged, artificial joint replacement surgery called arthroplasty is needed to replace the damaged bone.

Strategies for coping

Surgical research

A surgical treatment under study involves drilling a hole into the affected bone in the early stages of the disease, before major damage has occurred. This procedure relieves the increased pressure usually present within the bone, and may slow the progress of the condition. Meanwhile research into the causes and cures for osteonecrosis is continuing. We hope that one day it will be possible to prevent this condition and to treat it more effectively.

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