The correlation of morphological characteristics of fibrillar structure of bone matrix and its mechanical properties from the points of the theory of weak link

Purpose. To determine the effect of the scale factor (the increase of fibrils in diameter) on the strength properties of bone structures in organism’s aging based on the results of the authors’ own studies, as well as on those of other authors. Results. The increase of fibrils in diameter in organism’s aging demonstrated to be an additional factor of bone structure mechanical weakening. The relationship between mineral matrix structures is the morphological basis of “weak link”. The local disagreement of the direction of acting forces and the longitudinal axes of mineral structures is a biomechanical condition of breaking these relations. This disagreement is caused by the fact that the morphological basis of bone tissue at each skeletal locus is relatively unchanged, and the direction of acting forces when performing locomotor functions is changing at all times, as well as their value. As a result, the locus of the greatest disagreement of the longitudinal axes of mineral structures and that of the direction of acting forces is steadily «migrate» in a particular part of bone tissue. It has been demonstrated in the development of the theory of «weak link» that under animate nature conditions the process of exchanging and continuous updating bone structures in aging leads to an increase in the absolute number of «weak links». Conclusion. Under animate nature conditions the regulatory-and-metabolic shifts in the process of exchanging and continuous updating bone structures cause an increase in the absolute number of «weak links». It is this increase being one of the reasons of exponential reducing the strength properties of bone structures, for example, during the aging.