Weight loss can protect knees

Obesity is a major risk factor for osteoarthritis, a degenerative joint disease.

"Degenerative joint disease is a major cause of pain and disability in our population, and obesity is a significant risk factor," said the study's lead author Alexandra Gersing from University of California-San Francisco.

Gersing and colleagues investigated the association between different degrees of weight loss and the progression of knee cartilage degeneration in 506 overweight and obese patients.

The patients either had mild to moderate osteoarthritis or risk factors for the disease.

They were divided into three groups: a control group who did not lose weight, a second group who lost a little weight, and a third group who lost more than 10 percent of their body weight.

When the researchers analysed differences in the quality of cartilage among the three groups over a four-year time span, they found evidence that weight loss has a protective effect against cartilage degeneration and that a larger amount of weight loss is more beneficial.

"Cartilage degenerated a lot slower in the group that lost more than 10 percent of their body weight, especially in the weight-bearing regions of the knee," Gersing said.

However, those with five to 10 percent weight loss had almost no difference in cartilage degeneration compared to those who did not lose weight, the study found.

"Substantial weight loss not only slows knee joint degeneration, it also reduces the risk of developing osteoarthritis," Gersing said.

The study was presented at the annual meeting of the Radiological Society of North America (RSNA).