Poor Thigh Muscle Strength Increases Knee OA Risk?

Sometimes it’s great to be a woman…sometimes not. New research has found that among women, poor thigh muscle strength may increase the risk of knee osteoarthritis (OA). This, however, does not apply to men.

The study, published in the February edition of Arthritis Care & Research, was entitled, “Thigh muscle specific strength and the risk of incident knee osteoarthritis: The influence of sex and greater body mass index.”

Adam Culvenor, Ph.D., lead author of the study, told OTW, “Thigh muscle weakness, particularly of the knee extensors (quadriceps), is a common feature of people with knee osteoarthritis. Thigh muscle weakness could be a consequence of knee osteoarthritis, or precede knee osteoarthritis development. There is conflicting evidence regarding the role of thigh muscle weakness as a risk factor for incident knee osteoarthritis in both men and women. Thigh muscle specific strength is a measure of muscle quality incorporating both the capacity of the muscle to produce force as well as muscle structure (i.e., size, cross-sectional area), and preliminary data suggests this may be a more relevant measure of strength in relation to knee osteoarthritis development.”

Commenting on the results, Dr. Culvenor noted, “Deficits in thigh muscle specific strength (both knee extensors and flexors) increased the risk of radiographic knee osteoarthritis over a four-year follow-up period in women only, and not in men. This relationship in women was confounded by BMI [body mass index]—a potent risk factor for knee osteoarthritis itself. Looking more specifically at how muscles respond to variations in BMI, differences between men and women may explain our primary result, with more contractile tissue (and strength) being present in men with greater BMI, and apparently more non-contractile (adipose) tissue in women with greater BMI.”

“Our results suggest that muscle specific strength (i.e., muscle quality) is more closely related to radiographic knee osteoarthritis presence than muscle strength (i.e., muscle force) alone. Our findings of an increased risk of knee osteoarthritis with thigh muscle strength deficits in women only add to the growing body of evidence that women, but not men, with thigh muscle weakness are at an increased risk of knee osteoarthritis and progression to total knee joint replacement.”

“International clinical guidelines recommend exercise therapy, such as muscle strengthening and neuromuscular control, as the first line of treatment for knee osteoarthritis, along with patient education and weight control. While it is not possible to guarantee that having strong thigh muscles will protect women from developing knee osteoarthritis because there are many other factors that play into the disease, our results suggest that optimizing quadriceps and hamstring strength may help to lower the risk of developing knee osteoarthritis.”