Adiponectin is associated with bone strength and fracture history in paralyzed men with spinal cord injury

Summary We explored the association between adiponectin levels and bone strength in paralyzed men with spinal cord injury. We found that bone strength was inversely associated with circulating adiponectin levels. Thus, strength estimates and adiponectin levels may improve fracture risk prediction and detection of response to osteogenic therapies following spinal cord injury. Purpose Previous research has demonstrated an inverse relationship between circulating adiponectin and bone mineral density, suggesting that adiponectin may be used as a biomarker for bone health. However, this relationship may reflect indirect effects on bone metabolism via adipose-mediated mechanical pathways rather than the direct effects of adipokines on bone metabolism. Thus, we explored the association between circulating adiponectin levels and bone strength in 27 men with spinal cord injury. Methods Plasma adiponectin levels were quantified by ELISA assay. Axial stiffness and maximal load to fracture of the distal femur were quantified via finite element analysis using reconstructed 3D models of volumetric CT scans. We also collected information on timing, location, and cause of previous fractures. Results Axial stiffness and maximal load were inversely associated with circulating adiponectin levels ( R 2 = 0.44, p = 0.01; R 2 = 0.58, p = 0.05) after adjusting for injury duration and lower extremity lean mass. In individuals with post-SCI osteoporotic fractures, distal femur stiffness ( p = 0.01) and maximal load ( p = 0.005) were lower, and adiponectin was higher ( p = 0.04) than those with no fracture history. Conclusions Based on these findings, strength estimates may improve fracture risk prediction and detection of response to osteogenic therapies following spinal cord injury. Furthermore, our findings suggest that circulating adiponectin may indeed be a feasible biomarker for bone health and osteoporotic fracture risk in paralyzed individuals with spinal cord injury.