To evaluate the association of fatty infiltration of the quadriceps and vastus medialis (VM) with increase in knee cartilage, meniscus, or bone marrow lesions (BML) from MRI in knee osteoarthritis (OA) over 3-years.
Participants (n=69) with and without radiographic knee OA underwent MRI at baseline and 3-years later. Chemical shift-based water/fat MRI were used to quantify the intramuscular fat fraction and the lean anatomical cross-sectional area (ACSA) for the VM and entire quadriceps muscles. MRI images of the knee were analyzed using semi-quantitative modified WORMS (mWORMS) grading to assess change in lesions in the articular cartilage, meniscus, and BML. Logistic regression was used to assess if baseline quadriceps and VM fat fraction and lean ACSA were associated with increase in mWORMS scores. Odds ratios (ORs) were adjusted for age, sex, and BMI.
Overall 62% (43/69) of subjects had an increase in cartilage (26/43), meniscus (19/43), or BML (22/43) scores. Quadriceps (OR: 2.13 [95% confidence interval: 1.09, 4.15]) and VM (OR: 2.05 [95% confidence interval: 1.25, 3.36]) fat fraction were both associated with an increase in cartilage, meniscus, or BML scores over 3-years. The association of quadriceps or VM lean ACSA with the outcomes was not significant.
These longitudinal findings using quantitative MRI methods for assessment of muscle adiposity highlight the role of quadriceps adiposity, specifically VM, in knee OA progression. However, studies in larger cohorts are needed to confirm these findings.

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