To assess the differential features of marrow adiposity between osteoarthritis (OA) and osteoporosis (OP) in postmenopausal women using water/fat MRI.
This cross-sectional study included 97 postmenopausal women (OA [n = 25], OA + osteopenia [n = 27], OA + OP [n = 23], and OP groups [n = 22]). Water/fat MRI, dual-energy x-ray absorptiometry and biochemical analysis were performed to assess vertebral marrow fat fraction, bone mineral density, and bone biomarkers, respectively. Harris Hip Score was recorded to evaluate hip function.
There were significant differences in marrow fat content among the OA, OA + osteopenia, and OA + OP groups, between OP and OA participants with normal bone mass or osteopenia (all P < 0.05); no significant difference was observed between OA + OP and OP groups. Serum levels of leptin and β-Crosslaps in OA with normal bone mass and osteopenic OA groups were higher than in OP group. Marrow fat fraction was inversely correlated with Harris Hip Score (r = -0.371, P = 0.013), bone mineral density (r = -0.554, P = 0.009) and leptin levels (r = -0.610, P < 0.001). In multivariate regression analysis, marrow fat fraction was found to have a consistent and unchanged inverse association with leptin levels (Sβ = -0.311, P = 0.002) and bone mineral density (Sβ =  -0.265, P = 0.006) after adjusting for age, years since menopause, and body mass index.
Postmenopausal OA with OP have a phenotype with higher marrow adiposity. OA and OP could coexist, for the presence of a specific subgroup of OA with increased marrow fat accumulation and high risk of developing OP.