Prediction of Cortical Bone Thickness Variations in the Tibial Diaphysis of Running Rats

Abstract

A cell-mechanobiological model is used for the prediction of bone density variation in rat tibiae under medium and high mechanical loads. The proposed theoretical-numerical model has only four parameters that need to be identified experimentally. It was used on three groups of male Wistar rats under sedentary, moderate intermittent and continuous running scenarios over an eight week period. The theoretical numerical model was able to predict an increase in bone density under intermittent running (medium intensity mechanical load) and a decrease of bone density under continuous running (higher intensity mechanical load). The numerical predictions were well correlated with the experimental observations of cortical bone thickness variations, and the experimental results of cell activity enabled us to validate the numerical results predictions. The proposed model shows a good capacity to predict bone density variation through medium and high mechanical loads. The mechanobiological balance between osteoblast and osteoclast activity seems to be validated and a foreseen prediction of bone density is made available.

Effects of different running intensities on the micro-level failure strain of rat femoral cortical bone structures: a finite element investigation

“…Running exercise is recognized as an effective way to improve bone mechanical properties, and running with the appropriate intensity could increase bone density and strength [ 4 , 5 ]. Several experiments considered that the fracture load, cortical bone thickness, and tissue-level elastic modulus in the rat femoral and tibial cortical bone structures significantly increased under treadmill running at low or moderate intensity [ 6 – 8 ]. However, different viewpoints exist in the studies on the effects of high-intensity running on the mechanical properties of cortical bone.…”

“…Current experiments can obtain the macro- and nano-levels mechanical parameters but have difficulties in measuring the micro-level mechanical parameters in cortical bone structure [ 15 , 16 ]. Most studies only reported the changes in the microstructural morphology parameters under different loading environments [ 6 , 12 ]. The effects of micromechanical parameters on cortical bone fracture performance are significant, especially for micro-level failure strain in the osteon [ 17 ].…”