In vivo linear microcracks of human femoral cortical bone remain parallel to osteons during aging.

Previous studies have examined the density of microdamage within the cortex of long bones mostly from the viewpoint that is perpendicular to the long axis of the bone. The goal of the present work is to conduct a systematic characterization of the microcracks from a viewpoint that is parallel to the long axis of a load-bearing bone, the femur, so as to gain a better understanding of the size, shape and orientation of the microdamage. Longitudinal cross sections were taken at the mid-diaphysis of femurs from 13 male donors (23-85 years old) after being stained with basic fuchsin.

Microcracks colocalize within highly mineralized regions of cortical bone tissue.

While much work has been performed to quantify the extent of bone damage, its effects on the mechanical integrity of the tissue and its biological impact, the set of factors which gives forth to microdamage are nebulous, particularly the compositional properties local to microdamage. In this context, the current study tested the hypothesis that microcracks initiate within more mineralized regions of bone. Cortical bone specimens were taken from human male donors aged 31, 38, 53, 64, 71, and 84 years at the mid femoral diaphysis in a plane parallel to the osteonal orientation.

Fracture mechanics of cortical bone tissue: a hierarchical perspective.

The performance of bone tissue in the presence of flaws is a highly remarkable one. Bone tissue is the outcome of an adaptive evolutionary process; thus, insight into the mechanisms by which it fails would provide valuable information not only for development of mechanically superior biomimetic materials but also for development of treatment modalities to prevent debilitating bone fractures. Clinically, fractures of skeletal organs occur as a result of aging, disease, overuse, and trauma.