Figure 1.
Sample preparation: the same surface is imaged with three high resolution techniques.
A thin slice of 18 microns in thickness was cut at the surface of the sample block by microtomy to perform SAXS. A stick of 2×2 mm2 which included the region scanned by SAM was cut from the block and imaged using SR-µCT.
Figure 2.
SAM image (amplitude of the reflected ultrasound beam coded in gray levels).
The data analysis was performed on an identical site-matched area on each one of the two investigated osteons (namely ost1 and ost2).
Figure 3.
Comparison between local elastic properties and mineral ultrastructural characteristics.
From top to bottom: A acoustic impedance (Z), B degree of mineralization of bone (DMB), C T-parameter linked to the mineral thickness, D ISAXS related to changes in the lamellar orientation (the results are illustrated for ost1). For each investigated parameter, the solid line represents its variations along a radial profile going from the Haversian canal to the outer lamellae. The dashed line represents the corresponding smoothed profile after averaging the values between adjacent peaks. The coefficient of variation of the root-mean-square error CV(RMSE) provides a measure of the relative amplitude fluctuations of the measured values around the averaged profile curves.
Figure 4.
Result of the spatial frequency analysis performed on the Z, ISAXS, and T images.
The two plots display the normalized power spectral density as a function of the spatial oscillations (i.e. the inverse of the spatial frequency) on ost1 (A) and ost2 (B).
Figure 5.
SAXS calibration of the mineral nanoparticle orientation.
A Composite image showing the 2D SAXS pattern as a function of scan position along the radial direction of the osteon and tilt angle ω; B zoom in the innermost part of the scan (close to the Haversian canal); C map of the intensity ISAXS along the direction of the scan across the osteon as a function of the tilt angle, with the result of the fit overlaid in the form of white dots indicating a maximum. The position of the maximum was calculated by fitting the tilt profiles (from −60° to 60°) at each scan point by a sine function; D correlation between ISAXS and the angular position of the maximum ISAXS measured when tilting the sample between –60° and +60°.
Figure 6.
Site matched images on ost1: DMB map (left), Z-map (right, background) and ISAXS map (right, foreground).
Figure 7.
Minima and maxima of acoustic impedance (Z) and mineral orientation (ISAXS) show a positive correlation (linear regression for the pooled data from ost1 (▾) and ost2 (•).