The adaptive response of rat tibia to different levels of peak strain and durations of experiment.

The osteogenic response of bone to compressive load is affected by peak strain and duration of experiment, however, combined effect of peak load and duration of experiment on the rat tibia axial loading model remains unclear. In this study, rat tibia axial loading models with different levels of peak strains and durations of experiments were established (peak loads: 10 N, 20 N and 40 N, experimental duration: 2 weeks and 4 weeks). Microcomputer tomography scanning (Micro-CT), compression mechanical test and bone tissue alkaline phosphatase (ALP) and tartrate-resistant acid phosphatase (TRAP) staining were used to investigate the effects of cyclic loading with different levels of peak strains and durations of experiments on osteogenic response of tibia in adult female Sprague-Dawley (SD) rats. This experiment demonstrates that high-level strain can significantly stimulate the osteogenic response of cancellous and cortical bones in a short period of time. However, under mid-level strain, prolonging the experiment time can significantly improve the microsturcture and macromechanical properties of bone, increase the number of osteoblasts, and achieve the goal of improving bone quality. In this study, two loading schemes of mid-level-long-term and high-level-short-term were analyzed, and the mechanical response of the tibia under two different loading schemes was investigated. It provided a theoretical basis for further promoting the study of improving human bone quality and preventing aging-related bone diseases through mechanical stimulation.