8% (Figure 2(b)). The value of the reaction force occurring for a given displacement was the result of calculation.2.6. BMD AssessmentBMD (bone mineral density) assessment was performed method with dual energy X-ray absorptiometry DEXA apparatus (Lunar��Expert device (GE, WI, USA)) with projection parallel to the cylindrical sample’s axis.2.7. StatisticsWhen defining the relationships of volume of bone, fractal dimensions, and BMD with force the Pearson determination coefficients were applied. Curve fitting was performed by using Excel (Excel 2003, Microsoft, USA) software.3. ResultsTable 1 shows the results of BMD, Dfm, and Vm of the samples with mean, minimal, maximal values, SD and RSD for all assessed parameters. Table 1Bone mineral density, fractal dimension and volume of the bone layer related to applied force.

The range of variability of BMD was within 0.121 to 0.404 with mean value of 0.243. This variability was within the range between 50% and 166% of the mean value of the BMD. The range of variability of mean fractal dimension was within 1.302 to 1.702 with mean value of 1.567. This variability was within the range between 83.1% and 109% of the mean value of the fractal dimension.The range of variability of mean bone volume of the layers was within 0.155 to 0.944mm3, with mean value 0.531mm3. This variability was within the range from 29% to 178% of the mean value of the volume.The values of relative standard deviation (RSD) for Dfm and Vm for every sample are showed in Figure 3. The sample variability of the fractal dimension of the layers of the samples described by relative standard deviation RSDDfm was smaller than RSDVm.

The highest values of RSD for both parameters are observed mostly for samples with relative small values of force F. The values of RSD show similar dynamic of its change.Figure 3Values of RSD for Dfm and Vm.In Figures Figures44�C6 the relations between the BMD, mean fractal dimension, mean volume, and compression force F are presented. In Table 2, we present the values of the determination coefficients R2 for this relation when utilizing linear regression to describe this relation with exponential function. The highest values of determination coefficient were obtained for relation between the mean fractal dimension Dfm and force F (R2 = 0.9, P value 2.973?10?10) and the mean volume Vm (R2 = 0.88, P value 3.338?10?15) and force, F.

For BMD and force R2 was 0.53 (P value 6.587?10?8).Figure 4Relation between force F and bone mineral density BMD.Figure 6Relation between force F and mean Batimastat volume Vm.Table 2Strength of correlation expressed as determination coefficient R2 of force F relation mean volume Vm, mean fractal dimension Dfm, and BMD.To show the differences in structure of samples three specimens were taken, assigned as sample 1�C3.