July 16, 2009

Obesity and Rapid Cartilage Loss

Obesity, among other factors, is strongly associated with an increased risk of rapid cartilage loss, according to a study published in the August 2009 issue of Radiology.

“We have isolated demographic and MRI-based risk factors for progressive cartilage loss,” said the study’s lead author, Frank W. Roemer, M.D., of Boston University. “Increased baseline body mass index (BMI) was the only non-MRI-based predictor identified.”

Osteoarthritis is normally a slowly progressive disorder, but a minority of patients who had hardly any osteoarthritis at first diagnosis exhibited rapid disease progression. Researchers set out to identify baseline risk factors that might predict rapid cartilage loss in patients with early knee osteoarthritis or at high risk for the disease.

Osteoarthritis is the most common form of arthritis, affecting 27 million Americans, according to the National Institute of Arthritis and Musculoskeletal and Skin Diseases. In osteoarthritis, the cartilage breaks down and, in severe cases, can completely wear away, leaving the joint without a cushion. The bones rub together, causing further damage, significant pain and loss of mobility. The best way to prevent or slow cartilage loss and subsequent disability is to identify risk factors early.

The results of the study showed that the top risk factors contributing to rapid cartilage loss were high BMI, tears or other injury to the meniscus (the cartilage cushion at the knee joint) and severe lesions seen on MRI at the initial exam. Other predictors were synovitis (inflammation of the membrane that lines the joints) and effusion (abnormal build-up of joint fluid).

Excess weight was significantly associated with an increased risk of rapid cartilage loss. For a one-unit increase in BMI, the odds of rapid cartilage loss increased by 11 percent. No other demographic factors–including age, sex and ethnicity–were associated with rapid cartilage loss.

As obesity is one of the few established risk factors for osteoarthritis, it is not surprising that obesity may also precede and predict rapid cartilage loss. Weight loss is probably the most important factor to slow disease progression.

For patient-friendly information on MRI, visit www.RadiologyInfo.org.

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