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.