An investigation into the effects of osteocytes density and mechanosensitivity on trabecular bone loss in aging and osteoporotic individuals

Purpose: Optimal bone remodeling is responsible for bone health and strength, and an imbalance in this process may cause diseases such as osteoporosis. Both osteocyte density and mechanosensitivity are effective parameters in changing bone apparent density. This study aimed at investigating the effects of osteocyte density in healthy adults, and osteocyte mechanosensitivity in osteoporotic bones, on bone loss using a semi-mechanistic bone remodeling theory. Methods: A 2-D finite element model of trabecular bone was developed in order to simulate the process of bone remodeling. The structure was loaded by a sinusoidal stress, cycling between 0 and 2 MPa, and at frequency of 1 Hz. It was assumed that the stimulus sensed by osteocytes is the maximal strain energy density rate. By changing osteocyte density and mechanosensitivity, the effects of altering external load magnitude and/or direction were investigated. Results: First, trabecular-like structures were obtained from the initial configuration, in which trabeculae were lined up with the loading direction as verification of model’s implementation. Secondly, it was demonstrated that bone loss could occur in healthy older trabecular bone model, compared to healthy young bone model. Finally, this in silico study showed that by decreasing osteocyte mechanosensitivity, assuming a constant osteocyte density, a decrease in bone apparent density is predicted. Conclusions: Results of this work indicated that the semimechanistic model used here may reasonably explain bone loss in healthy adults and in osteoporotic patients. Moreover, this study sheds more light on the possible effects that osteocyte density in healthy adults, and osteocyte mechanosensitivity in osteoporotic individuals, may have on bone apparent density predictions. © 2015, Korean Society of Medical and Biological Engineering and Springer.