Abstract
This study aimed to elucidate the relationship between the quantitative value of suprapatellar effusion and the longitudinal changes in lower-extremity muscle mass (MM) in a cohort with knee osteoarthritis (KOA). Fifty-three subjects (106 legs) with bilateral radiographic KOA at baseline (BL) were enrolled. MM was calculated by bioimpedance analysis three times at BL, and at the one-year (1Y) and three-year (3Y) follow-ups. The longitudinal change in the lower-extremity MM was calculated by subtracting MMBL from MM1Y, and MM1Y from MM3Y. Subjects with ≥1.0 z-score loss were defined as having severe MM loss (SMML). Effusion was evaluated as the sagittal area of suprapatellar pouch (mm2) by ultrasonography. The ROC curve was drawn to determine the cut-off of effusion area. General estimating equations (GEEs) were conducted with the prevalence of SMML as the dependent variable and with the cut-off of effusion area as the independent variable. Sixteen legs (15.1%) demonstrated SMMLBL-1Y and another sixteen legs demonstrated SMML1Y-3Y. GEEs revealed that individuals with ≥90 mm2 effusion had significantly higher odds of SMMLBL-1Y prevalence (Odds ratio: 21.561; P-value: 0.003). Individuals with leachate knee effusion at BL had a significant risk of losing MM through the first year of the initial knee effusion assessment.
Highlights
This study aimed to elucidate the relationship between the quantitative value of suprapatellar effusion and the longitudinal changes in lower-extremity muscle mass (MM) in a cohort with knee osteoarthritis (KOA)
Based on the −1.0 z-score of ΔMM, a decline of 0.40 kg MM or more was defined as SMMLBL-1Y and 0.43 kg MM or more was SMML1Y-3Y
Based on the scatter graph comparing effusion area and change (Δ) in lower-extremity MM, the suprapatellar effusion area was negatively correlated with ΔMMBL-1Y (R2 = 0.057; P = 0.014)
Summary
This study aimed to elucidate the relationship between the quantitative value of suprapatellar effusion and the longitudinal changes in lower-extremity muscle mass (MM) in a cohort with knee osteoarthritis (KOA). In patients with KOA, there is a lack of evidence associating pathological mechanisms with the severity of knee effusion and MM loss of the lower-extremities. In the present cohort study, there were two purposes: first, based on a previously reported ultrasonographic technique[25], we retrospectively determined the quantitative value of knee effusion in patients with KOA at baseline (BL) to identify those who demonstrated loss of lower-extremity MM; second, we analyzed the relationship between the quantitative value of knee effusion at BL and changes in lower-extremity MM for the www.nature.com/scientificreports cohort. Our hypothesis was that those who demonstrated more leachate knee effusion would be more likely to develop the loss of lower-extremity MM during the 3-year follow-up
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