Summary: Knee OA is a disease more likely to occur in people who do more weight-bearing activity. This new study confirms that. But unlike past studies, it found the extra knee OA risk shows up only in people with less lower limb mass. In other words, sarcopenia (muscle loss from aging and inactivity) raises OA risk significantly.
Knee osteoarthritis is the most common joint disorder. Osteoarthritis hits weight-bearing joints like knees and hips. That is why it is also called a wear-and-tear disease.
But it is not that simple. A family history of osteoarthritis, certain nutrient shortfalls, and some lifestyle choices also add to the risk.
People who lift heavy weights over a lifetime, or who play certain sports, are also at risk. Put simply, more weight-bearing activity means more osteoarthritis (OA) risk.
Still, researchers have seen that some people never get OA, even with heavy physical activity. So there must be more to it.
The new study in JAMA Network Open looked at this question and found a lot. It studied data on 5003 adults who did weight-bearing recreational activities. Those activities significantly raised OA risk. Heavy weight-bearing activity raised knee OA risk by more than 20%.
But as they say, the devil is in the details. The researchers dug deeper into the data. After all, not everyone who did weight-bearing activities got knee OA over time.
When they looked closely, they found knee OA mostly showed up in people with low lower limb muscle mass. Simply put, people with thin, weak thighs got knee OA. People with moderate or high lower limb muscle mass did not.
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This is not only wear and tear or poor nutrition at work. It shows that keeping the legs strong, with more lower limb mass, may protect the knee.
So OA is, to a large degree, preventable. People with sarcopenia, the steady muscle loss that comes with aging and sitting too much, are at greater risk. That is why stopping age-related muscle wasting matters for preventing knee OA in adults.
Sarcopenia, or muscle loss from aging and inactivity, is known to raise the risk of falls and fractures in older adults. But this is one of the first studies to show that one of the most common joint disorders may also come from inactivity that strips muscle from the lower limbs, mostly the thighs.
Of course, researchers have long known that certain physical activities and stress may raise OA risk. They also knew regular exercise may help prevent or lower OA risk. This study adds to what we know.
It shows that some factors tied to aging may raise OA risk in some people. The higher knee OA risk shows up only in people whose thigh muscles have weakened from sarcopenia, or age-related muscle loss. Too little activity and poor nutrition make this muscle loss worse.
So, to prevent knee OA, start exercising, with a special focus on thigh muscle mass. This can significantly cut OA risk, even for people who do weight-bearing activities. This study also suggests that an interventional pain management center that focuses on keeping thigh muscle mass could help.
Source:
Wu, Y., Boer, C. G., Hofman, A., Schiphof, D., van Middelkoop, M., Szilagyi, I. A., Sedaghati-Khayat, B., Bierma-Zeinstra, S. M. A., Voortman, T., & van Meurs, J. B. J. (2024). Weight-Bearing Physical Activity, Lower-Limb Muscle Mass, and Risk of Knee Osteoarthritis. JAMA Network Open, 7(4), e248968. https://doi.org/10.1001/jamanetworkopen.2024.8968
Dr. Gurpreet Singh Padda, MD, MBA, MHP
