Effect of long-term cyclic compression loading on the structural evolution of trabecular bone

Abstract

Dynamic remodeling of bone tissue is mediated by the synergistic effects of osteoblast-driven bone formation and Osteoclast-dominated bone resorption. However, how bone cells perceive the mechanical stimuli and regulate bone remodeling have not been fully understood. This study aims to evaluate the effect of cyclic compression loading on trabecular microstructure for 42 days and identify the relationship between the evolution of trabecular microstructure and cell distribution. The eighth caudal vertebrae of rats were subjected to long-term cyclic compression loading with different frequencies. The compression displacement is 1 ​mm. In vivo micro-computed tomography was performed at 0, 14, 28 and 42 days to determine the structural parameters. The bone volume fraction (BV/TV) in the 1 ​Hz cyclic compression loading group was significantly higher than that in the control and 10 ​Hz groups, whereas the trabecular separation (Tb.Sp) was significantly lower. The 10 ​Hz cyclic compression group had the lowest BV/TV and highest Tb.Sp. After 14 days of loading, the BV/TV values of 1 ​Hz group were 29.62% and 41.6% higher than those of the control and 10 ​Hz groups, respectively. Conversely, the Tb.Sp of 1 ​Hz group was approximately 12.33% and 16.52% lower than that of the control and 10 ​Hz group, respectively. More bone formation and less bone resorption were observed in the 1 ​Hz group than the control group. In addition, more osteoblasts were attached to the area of bone formation, while more osteoclasts were located in the area of bone resorption. These findings may provide a basis for further understanding mechanical stimulation-regulated bone remodeling.