Obesity is a known risk factor for osteoarthritis, one of the leading causes of disability in the United States. A new study provides evidence that losing weight can slow the development of osteoarthritis of the knee by reducing the degeneration of knee cartilage.
Researchers found that overweight or obese adults experienced slower degeneration of knee joint structures after losing 5 or 10 percent of their body weight over 4 years, compared with those who did not lose weight.
Lead study author Dr. Alexandra Gersing, of the Department of Radiology and Biomedical Imaging at the University of California, San Francisco, and colleagues recently reported their findings in the journal Radiology.
The condition is caused by the breakdown of cartilage, the tissue that protects the joints at the ends of bones and enables them to move smoothly.
Being overweight or obese is a major risk factor for OA; the excess weight can put extra pressure on the joints and cartilage, causing "wear and tear."
Furthermore, Dr. Gersing and colleagues note that higher levels of body fat can lead to an increase in substances in the blood that trigger joint inflammation, which can raise the risk of OA.
For their study, the researchers set out to gain a better understanding of how weight loss affects joint health.
"We looked at the degeneration of all knee joint structures, such as menisci, articular cartilage, and bone marrow," notes Dr. Gersing.
Menisci are the pieces of fibrous cartilage that cushion and protect the surface of joints, while articular cartilage is the smooth, connective tissue that covers the ends of bones.
Weight loss slowed degeneration of menisci, articular cartilage
The researchers analyzed data from the Osteoarthritis Initiative, which included 640 adults who were either overweight or obese. All participants either had risk factors for OA or mild to moderate OA, as determined by MRI scans.
Over a period of 48 months, the researchers monitored changes in subjects' weight, as well as changes in knee degeneration.
Based on their weight changes over the 4-year period, participants were divided into three groups: adults who had lost more than 10 percent of their body weight, adults who had lost between 5 and 10 percent of their body weight, and adults who experienced no change in weight (the controls).
Compared with the control group, the researchers found that adults who had lost at least 5 percent of their body weight experienced slower knee cartilage degeneration, and this effect was even stronger among participants who lost more than 10 percent of their body weight.
"The most exciting finding of our research was that not only did we see slower degeneration in the articular cartilage, we saw that the menisci degenerated a lot slower in overweight and obese individuals who lost more than 5 percent of their body weight, and that the effects were strongest in overweight individuals and in individuals with substantial weight loss," says Dr. Gersing.
Overall, the researchers believe that their results demonstrate how weight loss may lower the risk of OA among individuals who are overweight or obese.
"Our study emphasizes the importance of individualized therapy strategies and lifestyle interventions in order to prevent structural knee joint degeneration as early as possible in obese and overweight patients at risk for osteoarthritis or with symptomatic osteoarthritis."
Dr. Alexandra Gersing