Rates of knee osteoarthritis have doubled in the United States since the 1940s, but it’s not just because Americans are living longer and weight more, a new study suggests.
To come to this conclusion, Harvard University researchers examined more than 2,000 skeletons from across the Unites States.
“We were able to show, for the first time, that this pervasive cause of pain is actually twice as common today as even in the recent past. But the even bigger surprise is that it’s not just because people are living longer or getting fatter, but for other reasons likely related to our modern environments,” said study first author Ian Wallace.
Wallace is a post-doctoral fellow in the lab of senior study author Daniel Lieberman, a professor of biological sciences at Harvard University.
The researchers are now working to find out what’s causing the increase. They said learning more about knee osteoarthritis is important not only because it affects a third of Americans over age 60, but because it is responsible for more disability than almost any other musculoskeletal disorder.
“Wouldn’t it be great if people could live to be 60, 70 or 80 and never get knee osteoarthritis in the first place?” Lieberman said in a Harvard news release. He noted that the disease is “almost entirely untreatable apart from joint replacement,” and once someone has it, it creates a vicious cycle. “People become less active, which can lead to a host of other problems, and their health ends up declining at a more rapid rate,” Lieberman explained.
For the study, published Aug. 14 in the Proceedings of the National Academy of Sciences, the authors examined research spanning more than 6,000 years of human history to search for a tell-tale sign of osteoarthritis.
“So using careful statistical methods, we are able to say that if you were born after World War II you have approximately twice the likelihood of getting knee osteoarthritis at a given age or BMI than if you were born earlier,” he said. BMI is a measure of body fat based on height and weight.
I suspect the “modern environmental factor” is lack of physical activity. Please review my blog “Is Running Bad for Your Knees?” posted on January 30, 2017. That study showed running reduces joint inflammation, the precursor to osteoarthritis.
The long held theory of osteoarthritis is that the repeated micro trauma to the surface of the two bones of any joint causes the breakdown of the cartilage and subsequent eburnation (the tell-tale sign of osteoarthritis) of the bone. However, a more current theory holds that the breakdown is due to loss of circulation in the joints rather than micro trauma.
Clinically, my patients suffering from osteoarthritis of the knee and those undergoing knee replacement tend to be less active than the average patient. I think Dr. Lieberman has it backwards – the osteoarthritis is due to inactivity rather than causing it. The knees are declining along with their general health.
The Bottom Line:
Physical activity is vital to preventing and treating osteoarthritis of the knees. Nutritional supplementation to maintain circulation may also be very helpful. I often recommend grape seed extract to strengthen the vascular walls.
Source: August 14, 2017 National Institutes of Health