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The purpose of this study was to determine the effect of Haversian remodeling on the tensile properties of human cortical bone by testing specimens containing, as far a possible, a single type of bone tissue. Fifty-one specimens were prepared from sixteen fresh tibias, removed at autopsy. Age range was 19-35. Regions were selected so that the specimens would consist almost exclusively of either primary bone or Haversian bone. The ultimate tensile strength, ultimate strain and Young's modulus of elasticity were determined at a loading rate of 0.05 mm s-1. The primary bone specimens were found to have a significantly higher ultimate tensile strength and modulus of elasticity than those formed of Haversian bone.

The predominant collagen fiber orientation in newly formed osteons was determined by polarized light microscopy. Osteons were classified into five categories according to the proportion of their cross section formed by dark lamellae. In dark lamellae most fibers run longitudinally or on a step spiral while they follow a circular or shallow spiral course in light lamellae. Types 1 and 2 are 'light' osteons; types 4 and 5 are 'dark', and type 3 is 'intermediate'. A significant correlation was found between the predominant collagen fiber orientation in osteons and the age at which their formation occurs. Significant differences were found also in the collagen fiber orientation in osteons among the different quadrants of the same bone.