Osteonecrosis, also called avascular necrosis (AVN), is a disorder in which bone cells suffer from a lack of oxygen and nutrients because of decreased blood flow. The bone subsequently dies leading to pain and collapse of the bone. This bone collapse, in turn, leads to collapse of the overlying cartilage, causing degenerative arthritis (osteoarthritis) of the nearby joints. The most common joints affected are the hips and knees. Other joints that are less often affected are the shoulders, hands, ankles, and feet.
In rare situations, osteonecrosis can affect the jaw, causing pain and mouth ulceration.
Conditions often associated with osteonecrosis are trauma which interrupts the bone’s blood supply, long-term use of corticosteroid medications, and excessive alcohol consumption.
Other conditions associated with osteonecrosis include:
1. Systemic lupus erythematosus
2. Sickle cell anemia
3. HIV infection
4. Radiation treatment
5. The “bends” that occur with scuba-diving where a person is spending time at great depths
6. Intravenous use of drugs such as bisphosphonates (osteonecrosis of the jaw).
Roughly, 10,000 – 15,000 Americans per year develop osteonecrosis and the disease is most common in people between the ages of 20 and 50. These patients usually have a history of trauma or corticosteroid use, excessive alcohol intake, or other conditions listed above.
Osteonecrosis of the jaw occurs as a rare complication of treatment with bisphosphonate medications. It has been seen primarily in patients with multiple myeloma or breast cancer who have received frequent doses of intravenous bisphosphonate medications such as zoledronate or pamidronate. It is rarely seen in patients treated for osteoporosis.
One of the earliest symptoms of osteonecrosis occurs when a patient with risk factors for the condition has localized bone pain. Hip pain due to osteonecrosis is often felt in the groin. It is aggravated by weight-bearing but also can be associated with pain at night. Pain due to knee osteonecrosis is also made worse with weight-bearing.
A diagnosis can be made occasionally, by getting an x-ray of the painful area. However, because x-rays can appear normal in the early stages of disease, other imaging studies such as bone scans or magnetic resonance imaging (MRI) can be helpful for diagnosis. MRI is probably the best diagnostic modality for very early osteonecrosis.
Osteonecrosis of the jaw is diagnosed by both seeing bare bone during examination and using dental x-rays.
Unfortunately, the treatment of osteonecrosis is not well-defined. No extablished guidelines exist.
It’s important to realize though that proper treatment starts with diagnosis.
Once the diagnosis has been established, pain medications and limited weight-bearing can be started. This type of conservative therapy sometimes works for patients with minor amounts of osteonecrosis.
However, it will not work for those with hip or knee osteonecrosis who are developing progressive bone collapse.
Instead, surgical procedures may be recommended to relieve pain and possibly prevent bone collapse.
A procedure called core decompression may be used to remove a core piece of bone from the affected area in an attempt to relieve pressure within the bone marrow and improve blood flow. If done early enough, this can prevent the progression of osteonecrosis.
In more advanced cases, patients may need a procedure called osteotomy where surgeons remove dead bone and re-position the bone so that the weight-bearing joint surface is supported by healthy bone.
If joint collapse has already occurred, total joint replacement of the hip or knee is often required to improve pain and function.
There is no clinically proven medical therapy for osteonecrosis, but some doctors suggest treatment with bisphosphonate medications such as alendronate (Fosamax) or residronate (Actonel). Recent studies have suggested that bisphosphonate medications may, at least in the short term, improve and slow or even prevent bone collapse.
Treatment of osteonecrosis of the jaw is unsatisfactory. Bisphosphonate medications should be stopped and antibiotics can be used to reduce the likelihood of infection. Analgesic medications can be helpful for pain relief.
The most important ways to prevent osteonecrosis are to avoid excessive alcohol intake and to limit the amount of corticosteroid use. Tobacco use also should be avoided as it has been suggested to be a risk factor for osteonecrosis.
Osteonecrosis of the jaw can be prevented with good dental hygiene. Dental work should be completed before starting bisphosphonate therapy or as soon after starting as possible. The dentist should be contacted immediately if there is any sign of dental inflammation.
Since most patients who develop significant osteonecrosis will also develop osteoarthritis (degenerative arthritis) as a consequence of the osteonecrosis, it is important to attend to that condition. Osteoarthritis due to osteonecrosis is treated similar to osteoarthritis occurring on its own.