Weight loss tied to lower risk of knee joint degeneration

Overweight and obese people who shed a lot of excess pounds may have less damage in their knee joints than their counterparts who don’t lose weight, a recent study suggests.

While previous research has linked obesity to an increased risk of joint disease and cartilage damage in the knees, the current study underscores how weight loss may help minimize this risk.

Researchers followed 640 obese and overweight patients for four years. By the end of the study, participants who lost more than 10 percent of their weight were 66 percent less likely than people who didn’t lose any weight to show progression in the deterioration of their knee joint cartilage.

People who shed 5 percent to 10 percent of their weight were also less likely to have progression in knee joint damage, but the difference wasn’t big enough to rule out the possibility that it was due to chance.

“Our study shows that a lifestyle intervention such as weight loss can slow the process of knee joint degeneration in patients at risk for and with osteoarthritis and therefore may slow the worsening of symptoms such as pain and disability, said lead study author Dr. Alexandra Gersing of the University of California, San Francisco.

“The more weight loss the patients achieved, the greater the benefits were, even if they remained obese after losing weight,” Gersing said by email.

Osteoarthritis is the most common joint disease in the United States, affecting more than half of people 75 and older, researchers note in the journal Radiology. Compared with people at normal weight, obese women are nearly four times more likely to develop knee osteoarthritis, while obese men have five times the risk.

At the start of the study, participants were 63 years old, on average, and typically very overweight or obese. Most of them had either minimal or moderate damage to the knee joint, based on magnetic resonance imaging (MRI) exams.

Four years later, roughly half of the participants were at about the same weight as when they started. Another 238 people lost between 5 percent and 10 percent of their weight and 82 participants lost more than 10 percent of their weight.

Not only did the researchers find that weight loss slowed cartilage degeneration, they also saw changes in the menisci, crescent-shaped pads that protect and cushion the joint.

The study wasn’t a controlled experiment designed to prove that weight loss prevents knee joint damage or osteoarthritis.

Limitations of the study include the lack of data on weight-loss methods participants used, which may have influenced what happened with their knee joints, the authors note.

Even so, the study offers fresh evidence of how weight loss may benefit the knee joints, said Dr. Leena Sharma, director of the Multidisciplinary Clinical Research Center in Rheumatology at Northwestern University Feinberg School of Medicine in Chicago.

“This study uniquely gets at the benefits of weight loss on specific tissue abnormalities in knee osteoarthritis and convincingly demonstrates the benefit of weight loss on the course of this common condition,” Sharma, who wasn’t involved in the study, said by email.

It should also encourage patients to consider the benefits of even a little bit of weight loss,” said Dr. Kent Kwoh, director of the University of Arizona Arthritis Center in Tucson.

“Losing weight can help overweight and obese patients protect their knees and keep their arthritis from getting worse,” Kwoh, who wasn’t involved in the study, said by email. “At this point in time, joint damage cannot be reversed; we can only keep it from getting worse.”

SOURCE: Radiology, online May 2, 2017.