Pinching in longitudinal and alternate osteons during cyclic loading

Orientation of collagen at the osteocyte lacunae in human secondary osteons

“…The angle between the elementary components' orientation and the loading direction was observed to affect strain and stress fields. The proposed ''lacuna-enhanced osteon'' model displays the axial deformation observed experimentally Bonucci, 1967, 1968;Ascenzi et al, 1985Ascenzi et al, , 1997. The mesh density was established through a convergence study on an increasing number of nodes, from 58,100 to 1,917,873.…”

“…The morphometric data were included in a series of finite element models that simulated the mechanical behavior of single secondary osteon Bonucci, 1967, 1968;Ascenzi et al, 1985Ascenzi et al, , 1997 with lacunae. To probe the role of collagen-apatite orientation, the alternative option was included to assign constant homogeneous material properties to all the elements of the model.…”

Hysteretic pinching of human secondary osteons subjected to torsion

“…The mathematical analysis followed previously described steps (Ascenzi et al, 1997). Briefly, Maple software (Waterloo Inc.) was employed to fit a cubic polynomial function f(x) ¼ (a(xÀh) 3 )/3+k(xÀh)+l, to each halfcycle after the first initial cycle.…”

“…The degree of calcification was fixed at the highest level and the appearance of osteon in cross-section under circularly polarized light was set to vary from specimen to specimen through the extent of the spectrum from extinct to bright. The osteon specimens were divided into the minimum number of groups of fixed number of specimens of essentially constant dimensions (Ascenzi et al, 1994(Ascenzi et al, , 1997.…”

“…Cyclic loading of bone specimens of various sizes and shapes from various vertebrates has been conducted under a variety of regimens (for a review, see Ascenzi et al, 1997). However, cycling loops that appear ''pinched'' or S-shaped, as opposed to C-shaped ( Fig.…”