The volume of these samples differ selleck catalog significantly��mean volume of sample 3 almost doubles that of sample 1.They also have different Dfm. There are slightly different RSDVm and RSDDfm for sample 1 and sample 2, and there is big difference between those values and the values for sample 3. The differences in value of force F are visible and they are in keeping with conclusion from Figures Figures55�C6 that with increasing Dfm and Vm the value force F also increases.Figure 5Relation between force F and mean fractal dimension Dfm.In Figure 7(a) we present selected fragments (3.6 �� 3.6 �� 3.6mm) of these three samples with different structure. The graphic presentation of volume (Figure 7(b)) and fractal dimension variability (Figure 7(c)) for every layer at sample height z are showed.

Despite similar BMD, the structure of the samples is different. The V and Df curves are similar (they show almost the same dynamic of change).Figure 7The structure of three selected samples: (a) curves of changes of volume V; (b) fractal dimension Df (c) along the axes of these samples.4. DiscussionUntil now BMD has been one of the major parameters used widely in medical practice to assess bone quality and indirectly the risk of fracture. Although the result of BMD gives the information on bone density, it does not give information about bone structure and its susceptibility to break. Bone mineral density shows low sensitivity and specificity, as over 50% of fractures occur in persons without osteoporosis in BMD exam and most women with osteoporosis assessed with this method do not sustain a fracture [24].

Langton et al. state that currently there is no accurate noninvasive measure of overall bone strength [25].We assumed that bone structure is not homogenous, and certain areas are less filled up with bone mass. We think that the process of breaking is initialized in some areas with lower strength. Thus, our studies considered microstructural level of bone (defined as 36-micron layer of bone). We assessed BMD, bone quantity in layer (expressed as volume of bone in layer), and bone structure (fractal dimension). Then, we combined these parameters with compression force.Although some papers reported on bone structure parameters and osteoporotic fractures [24, 26] and evaluation of bone layers [27], we were not able to find any paper about the correlation of bone volume in the layer with force and correlation of fractal dimension (2D) with this force and simultaneously we compare the results of BMD of the whole sample with force.

Thus, we planned to assess possible utility of these structural parameters in bone strength description.In our study we assumed that the force (F) caused 0.8% strain [28] Carfilzomib which corresponded with the elastic range of strain trabecular bone.