Objective To study bone remodeling behavior under different damage conditions. Methods A bone remodeling model under fatigue mechanism was proposed. By establishing a three-dimensional (3D) finite element model of the proximal femur and combining with the finite element method, the bone remodeling under three loading conditions was simulated, and the mechanical properties and density changes of the proximal femur were analyzed. Results The damage increased with the number of loading cycles increasing. Under different damage conditions, bone showed different remodeling behaviors. As a kind of repair mechanism, bone remodeling could make up for the loss of bone mass due to fatigue damage within a certain range. Conclusions The damage adaptive remodeling model proposed in this study can simulate the bone remodeling behavior under different damage conditions, and the overload absorption caused by excessive loading cycles. The study on the behavior of bone remodeling under fatigue damage can provide references for fracture prevention and postoperative rehabilitation treatment.

Objective To study the bone disuse behavior with electric field under low load stimulation frequency. Methods A disuse model was proposed to describe the effects of mechanical and electrical stimulation on bone remodeling through the activation frequency. By establishing the finite element model of proximal femur and using the finite element method, the process of bone remodeling under low load stimulation frequency coupled with electrical stimulation was simulated, and the loss of bone density was analyzed. Results The density was significantly decreased by decreasing the frequency of daily load stimulation frequency. The electrical stimulation could resist density loss caused by the low load stimulation frequency to a certain degree, and its main influence areas were distributed in the femoral head and femoral neck. The duration of electrical stimulation significantly affected density loss of the cortical bone and cancellous bone. Conclusions The model can simulate the process of disuse caused by the decrease of daily load stimulation frequency. Meanwhile, the effect of electric field is taken into account to show the resistance to bone density loss.