Features January 2007 Issue

Reducing Your Risk Of ‘Bone Death’

Osteonecrosis is a bone disease that results from oxygen-starved blood.You can prevent it, or catch it early...

Your bones, like all living tissue, need a constant source of oxygen-rich blood. If the blood supply is disrupted, cells in the bone begin to die and osteonecrosis, or bone death, results. Ultimately, the bone weakens and collapses.

Osteonecrosis can affect any bone or bones in a joint, but the most frequent sites are the hips, upper arms, shoulders, knees, wrists, and ankles. "The hip is the most common joint affected because there’s only one source of blood supply to the ball of the hip joint," says Daniel Mazanec, M.D., vice chairman of the Cleveland Clinic Spine Institute and head of the Section of Spine Medicine. "If that source is lost, there’s not another that can be relied upon to provide adequate circulation."

Ninety percent of the 10,000 - 20,000 people who develop osteonecrosis each year have an affected hip, and the disease is responsible for 10 percent of hip replacements. The good news is that early diagnosis and appropriate treatment can save bones and joints. Even better, you may be able to prevent the disease in the first place.

Who’s at risk?

While osteonecrosis can occur for no apparent reason, there are certain risk factors. A common one is overuse of steroids. Steroids may interfere with the body’s ability to break down lipids, a fatty substance that can clog blood vessels and inhibit blood circulation. Another cause is excessive alcohol use, which can lead to a build-up of fatty substances that block blood vessels. Injury, such as a fracture, can affect blood vessels, too; hip fractures and dislocations are major risk factors for osteonecrosis. Osteonecrosis is also associated with a number of medical conditions including lupus, rheumatoid arthritis, and inflammatory bowel disease.

Recent reports have linked high doses of intravenous osteoporosis drugs, called bisphosphonates, with jaw osteonecrosis that follows an infection after oral surgery. It’s believed that bisphosphonates may interfere with the blood flow needed to repair bone affected by bacteria from the mouth.

"This is an extremely rare complication," says Dr. Mazanec. "Ninety-five percent of patients who developed this type of osteonecrosis were taking long-acting bisphosphonates as part of a cancer program. You shouldn’t be discouraged from taking a drug for osteoporosis, such as Fosamax, if you need it."

Recognizing symptoms

Initially, osteonecrosis-related pain occurs when you put weight on the affected joint; later it can occur even when resting. As the disease progresses, pain can increase and may limit your range of motion.

"Osteonecrosis causes softening of the bone, making it vulnerable to weight-bearing damage that can lead to collapse or fracture," says Dr. Mazanec. "It’s essential to recognize osteonecrosis as soon as possible in order to prevent destruction of the joint."

Diagnosis is reached through physical examination and an MRI. Treatment usually involves pain medication, anti-inflammatory drugs, and crutches to lessen weight on the joint while the bone heals. (For osteonecrosis in other areas, rest and protection of the joint with a wrist splint, for example also apply.) Core-decompression hip surgery, which involves removing the inner core of bone, reduces pressure inside the bone, allowing blood vessels to widen and increasing blood flow.

Avoiding risk factors

"While corticosteroids have an important role, their overuse can lead to osteonecrosis," says Dr. Mazanec. "Limit their use to situations where they are absolutely necessary. The more steroids you take and the longer you’re on them, the higher the risk."

To avoid injury or trauma that can lead to osteonecrosis, use the same precautions that you would to avoid a hip fracture. Eliminate throw rugs, use caution on stairs, avoid sedatives that can make you groggy, and avoid excess alcohol consumption.