A new study has found that poor strength in the thigh muscles may increase the risk of knee osteoarthritis in women but not men. This relationship was confounded by body mass index (BMI), which itself is known as a risk factor for knee osteoarthritis.

The study's investigators noted that there may be more contractile tissue (and strength) present in men with greater BMI and more non-contractile (fat) tissue in women with greater BMI. The sex-specific relationship between muscle strength and BMI provides a possible explanation for why women with muscle strength deficits typically have a poorer prognosis than men with similar deficits.

"Our results highlight the importance of maintaining thigh muscle strength to reduce the risk of knee osteoarthritis development, particularly in women," said Dr. Adam Culvenor, lead author of the Arthritis Care & Research study. "The different relationships we observed between muscle weakness, muscle size, BMI and knee osteoarthritis development in men and women suggest that the mechanism by which BMI increases the risk of knee osteoarthritis is sex-specific and may require distinct treatment approaches."

Article: Thigh muscle specific strength and the risk of incident knee osteoarthritis: The influence of sex and greater body mass index, Adam G. Culvenor PT, PhD, David T. Felson MD, MPH, Jingbo Niu DSc, Wolfgang Wirth PhD, Martina Sattler MSc, Torben Dannhauer PhD and Felix Eckstein MD., Arthritis Care & Research, doi: 10.1002/acr.23182, published online 8 February 2017.