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The following is a summary of “Skeletal muscle composition, power, and mitochondrial energetics in older men and women with knee osteoarthritis,” published in the July 2024 issue of Rheumatology by Distefano PT et al.

Researchers conducted a retrospective study examining the relationship between the presence and severity of (KOA) and muscle composition, power, and energy in older adults, considering overall and sex-specific differences.

They included 655 older adults (average age 76.1±4.9 years, 57% females) from the Study of Muscle, Mobility, and Aging (SOMMA). Participants underwent standing knee radiographs with knee pain evaluations and were categorized into 3 groups based on the Kellgren-Lawrence grade (KLG) of knee osteoarthritis severity: 0-1, 2, or 3-4. The outcome was measured by assessing whole-body muscle mass, thigh fat-free muscle (FFM) volume, muscle fat infiltration (MFI), leg power, specific power (power normalized to muscle volume), and muscle mitochondrial energetics.

The result showed the association of KOA with pain, muscle function, and lower limb power. Participants with more severe KOA exhibited greater MFI, lower leg power, and specific power and reduced oxidative phosphorylation (P trend<0.036). When stratified by sex, the reductions in energetics were only observed in females (P trend<0.007) with KOA compared to controls. Additionally, after adjusting for various confounding factors, individuals with advanced KOA (KLG 3-4) demonstrated MFI (0.008% (0.004, 0.011), lower leg power (-51.56W (-74.03, -29.10)) and specific power (-5.38W/L (-7.31, -3.45)), compared to patients with no or mild KOA (KLG 0-1). No interactions between pain and KOA severity were detected. The analysis within the KOA group showed that MFI and oxidative phosphorylation were associated with thigh FFM mass, leg power, and specific power.

Investigators concluded that KOA impairs muscle health in both genders, but only females experience reduced mitochondrial energetics. 

Source: acrjournals.onlinelibrary.wiley.com/doi/abs/10.1002/art.42953