Estimation of local anisotropy of plexiform bone: Comparison between depth sensing micro-indentation and Reference Point Indentation. Issue 15 (26th November 2015)

• Record Type: Journal Article
• Authors: Dall'Ara, E.; Grabowski, P.; Zioupos, P.; Viceconti, M.
• Is Part Of: Journal of biomechanics. Volume 48:Issue 15(2015)
• Page Start: 4073
• Page End: 4080
• Publication Date: 2015-11-26
• Subjects: Bone -- Reference Point Indentation -- Micro-indentation -- Anisotropy -- Plexiform; Animal mechanics -- Periodicals; Biomechanics -- Periodicals; Biomechanics -- Periodicals; Mécanique animale -- Périodiques; Biomécanique -- Périodiques; Electronic journals; 571.4305
• DOI: 10.1016/j.jbiomech.2015.10.001
• Languages: English
• ISSNs: 0021-9290

Abstract

Abstract: The recently developed Reference Point Indentation (RPI) allows the measurements of bone properties at the tissue level in vivo . The goal of this study was to compare the local anisotropic behaviour of bovine plexiform bone measured with depth sensing micro-indentation tests and with RPI. Fifteen plexiform bone specimens were extracted from a bovine femur and polished down to 0.05 µm alumina paste for indentations along the axial, radial and circumferential directions ( N =5 per group). Twenty-four micro-indentations (2.5 µm in depth, 10% of them were excluded for testing problems) and four RPI-indentations (~50 µm in depth) were performed on each sample. The local indentation modulus E ind was found to be highest for the axial direction (24.3±2.5 GPa) compared to the one for the circumferential indentations (19% less stiff) and for the radial direction (30% less stiff). RPI measurements were also found to be dependent on indentation direction ( p <0.001) with the exception of the Indentation Distance Increase (IDI) ( p =0.173). In particular, the unloading slope US1 followed similar trends compared to the E ind : 0.47±0.03 N/µm for axial, 11% lower for circumferential and 17% lower for radial. Significant correlations were found between US1 and E ind ( p =0.001; R 2 =0.58), while no significant relationship was found between IDI and any of the micro-indentation measurements ( p >0.157). In conclusion some of the RPI measurements can provide information about local anisotropy but IDI cannot. Moreover, there is a linear relationship between most local mechanical properties measured with RPI and with micro-indentations, but IDI does not correlate with any micro-indentation measurements.