[Osteon count and tensile strength of human metacarpals and basic phalanges]

In a previous study the biochemical data of 45 metacarpal and 36 phalangeal bones of 21 male cadavers (24-69 years of age) were obtained by fracturing in a bending test. The present study attempts of correlate these data with the compacta area, the number of osteons, and the cross sectional area of the osteons. The relative and absolute number of osteons increase significantly with increasing age, whereas the average thickness of the compacta decreases significantly. The calibre of the bone marrow cavity increases with age. There is no correlation between age and osteon diameter. Ultimate bending deflection, bending breaking load, and breaking energy decrease following a reduction in compacta thickness or in the cross sectional area of the compacta. Bending tests on whole bones indicate that it is not so much bone tissue morphology, but rather the relationship of the marrow area to the total cross sectional area which is the significant factor in the bending behaviour of the whole bone.