Knee arthritis affects nearly 20 percent of Americans over the age of 45. In addition to pain, swelling and stiffness, it can cause disability, interfering with walking and climbing stairs. It is also a major cause of lost work time.
The incidence of knee arthritis today is double what it used to be, and a fascinating new study from Harvard suggests that we may have been wrong about the causes. The study concluded that knee arthritis is neither the wear-and-tear disease we have believed it to be nor the consequence of people today living longer or (in the U.S, especially) carrying more weight.
To reach these conclusions, the researchers studied more than 2,000 skeletons, some of them 6,000 years old. They focused on bones from prehistory, the 1800s and modern times. The oldest skeletons were those of prehistoric Inuit hunter-gatherers in Alaska; the most recent were from people who died in Tennessee in 2015. The signs of knee arthritis seen in the skeletons over time confirmed that the disease has increased dramatically in recent decades.
The researchers expected to see more physical changes indicative of knee arthritis in the older skeletons because of the additional physical activity required in ancient times and even during the 1800s. But, in fact, the older skeletons showed less of the problem. Study leader Daniel Lieberman, a professor of human evolutionary biology, suspects that the reason is today’s lack of physical activity – we spend much more time sitting than our ancestors. This may affect how joints form and age, leading to the upsurge in knee arthritis. He may be right. (A number of studies have found less knee arthritis in runners than in non-runners.)
Although the Harvard researchers haven’t yet pinpointed the cause, they are working to determine the risk factors in hopes that their findings will help lead to a way to prevent the disease.
There’s not much you can do to definitively treat knee arthritis other than get a joint replacement. However, losing weight can help reduce the pain and inflammation and increase the function of arthritic knees. Combining weight loss and exercise can help even more, according to a study from Wake Forest University, published in 2013. Here, researchers reported that 38 percent of study participants who lost weight, walked and did strength training for one hour 3 times a week, reported little or no knee pain.
In addition to weight loss and exercise, I recommend making some specific dietary changes to reduce arthritic inflammation and pain. Research has shown that omega-3 fatty acids and the spices ginger and turmeric may be of benefit. And foods rich in antioxidants – plentiful in most vegetables and fruits – may help reduce tissue damage from inflammation.
Andrew Weil, M.D.
Daniel E. Lieberman et al, “Knee osteoarthritis has doubled in prevalence since the mid-20th century.” Proceedings of the National Academy of Sciences, doi: 10.1073/pnas.1703856114