Possible effect between the molecular packing of collagen and the composition of bony tissues

Abstract

The weight fractions of the organic, mineral and water components of bone have been shown to be uniquely related to the wet bone density, except for a small variation possibly due to structure, for the range of bone densities from 1.7 g/cm 3 for deer antler to 2.7 g/cm 3 for porpoise petrosal. In this report the mathematical expression for the organic weight fraction is shown to depend on three factors, each a function of bone density. The first factor can be ralated to the mineral fraction, the second to the volume fraction of the organic component and the third to the density of the organic component. The influence of these factors is not obvious, since the change in the organic weight fraction could be due to an absolute loss of organic matter alone, or to a combination of increased mineral concentration together with some loss of organic matter. The mathematical development is based on the generalized packing model for collagen. It is demonstrated that the mineralization process requires a decrease of the organic component as well as a compaction of the collagen fibrils and these vary with the bone density.