[Investigations on the aging processes of the humerus by means of histomorphometry, regression and factor analysis...

Histomorphometric measurements were made on bone sections prepared from osseous material removed from the diaphysial center of 70 macerated humeri obtained from persons in their third to ninth decades of life. The diameters of osteons and Haversian canals, the densities of Haversian and Volkmann's canals and osteocytes, and the proportions by volume of special and interstitial lamellae were determined. The parameters were checked for age dependence and subjected, together with previously determined macroscopic dimensions of the same left humeri, to regression analyses. Influencing variables entering into the most suitable formula for age determination include the cross-sectional area of the medullary space in the diaphysial center as well as the smallest diameters of osteons and Haversian canals. Factor analysis of the complex structure of characteristics yielded 4 factors, namely, the age factor, size factor, structural factor, and nutritional factor. Also discussed are the processes of internal transformation of adult bones.