Is There a Link Between Hip Muscle Strength and Knee Osteoarthritis Risk in Women?

A recent study found that a lack of strength in the thigh muscles might increase the risk of knee osteoarthritis in female patients, but not men.

A team including researchers from Boston University School of Medicine hoped to determine whether lower thigh muscle strength increases the risk of incident radiographic knee osteoarthritis (RKOA), and whether a sex-specific relationship exists between thigh muscle specific strength and body mass index (BMI).
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The investigators examined 161 Osteoarthritis Initiative participants with incident RKOA, who were matched to 186 controls without incident RKOA. Overall, 62% of the patients from the incident RKOA group were female, in comparison to 58% of the control group. Thigh muscle anatomical cross-sectional areas (ACSAs) were determined at baseline using axial MRI scans, while isometric extensor and flexor muscle strength were measured at baseline, and specific strength was calculated. Logistic regression assessed risk of incident RKOA associated with muscle specific strength, with and without adjustment for BMI, according to the authors.

Overall, lower knee extensor and flexor specific strength significantly increased the risk of incident RKOA in women, but not men, the researchers noted, adding that the significant relationship in women was lost after adjustment for BMI. In addition, lower specific strength was linked to higher BMI in women, but not in men, while strength was associated with BMI in only men.

“The different results between men and women in our study could be explained by the muscles response to greater BMI,” said lead study author Adam Culvenor, PT, PhD.

“For primary care practitioners, it is important that female patients are educated about the importance of maintaining a healthy body weight through eating well and staying active. But, just as importantly, the protective value of having strong thigh muscles should also be emphasized, said Culvenor, noting that
“we know that doing strengthening exercises makes you stronger.”

While numerous factors make it impossible to guarantee that having strong thigh muscles will protect women, “having greater quadriceps strength probably helps to prevent knee osteoarthritis in women," added David Felson, MD, MPH, a professor of medicine and epidemiology at Boston University Medical Campus, and a co-author of the study. "This might be one way in which regular exercise can help prevent this disease."

—Mark McGraw

Reference

Culvenor AG, Felson DT, Niu J et al. Thigh muscle specific strength and the risk of incident knee osteoarthritis: The influence of sex and greater body mass index [published online February 8, 2017]. Arthritis Care & Research. doi:10.1002/acr.23182.