SARS Corticosteriods Linked to Osteonecrosis

According to a study published in The Journal of Bone and Joint Surgery – British Volume, the use of corticosteroids to treat SARS has been linked to the development of osteonecrosis, a debilitating joint disease.

SARS (Severe Acute Respiratory Syndrome) is a viral respiratory disease, which was first reported in a global outbreak in 2003 that sickened about 8,000 people and killed 774. It is caused by the SARS coronavirus, which affects the immune system and pulmonary epithelium.

The treatment for SARS often involves giving regular high doses of corticosteroid (glucocorticoids), which are synthetic derivatives of the natural steroid, cortisol, produced by the adrenal glands. Cortisol plays a role in regulation of the immune response which is affected by the SARS virus.

The new study reviewed the link between steroid dosage and the number of osteonecrotic lesions that developed among individuals treated in Beijing, China during the 2003 SARS outbreak. Researchers found that 43 patients out of 114 (37.7%) involved in the study developed osteonecrosis. These 43 patients received significantly higher doses of corticosteroids and had been treated for longer than those who did not develop the joint disease.

Osteonecrosis involves the death of bone cells that results from a decrease in blood flow to the bone tissue. Also known as avascular necrosis or bone necrosis, the joint disease can be severely debilitating.

MRI scans are used to diagnose the early stages of the disease. If untreated, the bone may collapse, requiring total joint replacement. Symptoms include severe pain and aching of the joints, and impaired mobility.

Osteonecrosis most commonly affects the two ends of the femur and the hipbone, but osteonecrosis of the shoulder, osteonecrosis of the knee and osteonecrosis of the jaw are also known to occur. In recent years, osteonecrosis has also been associated with the extended use of osteoporosis drugs like Fosamax and other bisphosphonates.

The researchers recommend that future SARS patients be treated with lower doses of steroids, since the number of osteonecrotic lesions was dose-dependent. The steroids affect vascular flow, which may explain why the flow of blood to the bones is reduced by excessive doses of steroids, causing osteonecrotic lesions.