An Application of Nanoindentation Technique to Measure Bone Tissue Lamellae Properties

Abstract

Measuring the microscopic mechanical properties of bone tissue is important in support of understanding the etiology and pathogenesis of many bone diseases. Knowledge about these properties provides a context for estimating the local mechanical environment of bone related cells thait coordinate the adaptation to loads experienced at the whole organ level. The objective of this study was to determine the effects of experimental testing parameters on nanoindentation measures of lamellar-level bone mechanical properties. Specifically, we examined the effect of specimen preparation condition, indentation depth, repetitive loading, time delay, and displacement rate. The nanoindentation experiments produced measures of lamellar elastic moduli for human cortical bone (average value of 17.7 +/- 4.0 GPa for osteons and 19.3 +/- 4.7 GPa for interstitial bone tissue). In addition, the hardness measurements produced results consistent with data in the literature (average 0.52 +/- 0.15 GPa for osteons and 0.59 +/- 0.20 GPa for interstitial bone tissue). Consistent modulus values can be obtained from a 500-nm-deep indent. The results also indicated that the moduli and hardnesses of the dry specimens are significantly greater (22.6% and 56.9%, respectively) than those of the wet and wet and embedded specimens. The latter two groups were not different. The moduli obtained at a 5-nm/s loading rate were significantly lower than the values at the 10- and 20-nm/s loading rates while the 10- and 20-nm/s rates were not significantly different. The hardness measurements showed similar rate-dependent results. The preliminary results indicated that interstitial bone tissue has significantly higher modulus and hardness than osteonal bone tissue. In addition, a significant correlation between hardness and elastic modulus was observed.

Mechanical property determination of bone through nano- and micro-indentation testing and finite element simulation

“…As noted in the literature Hoffler et al, 2005), there are differences in the measured modulus and hardness values when testing hydrated vs. dry specimens, thus the measured values presented here would likely decrease if tested under hydrated conditions. It is not clear, however, whether or not the maximum high-load penetration depths encountered in this study (on the order of 3000 nm, 3-5 times larger than in Rho and Hoffler, respectively) would still result in significantly different hydrated vs. dry results; and whether or not the trends observed between hydrated and dry specimens would be similar to those observed in this study.…”

“…An increasing number of measurements of hardness and Young's modulus of bone have been made using different nano-instruments (Turner et al, 1999;Hengsberger et al, 2003;Rho and Pharr, 1999;Hoffler et al, 2005;Ashman and Rho, 1988;Fan et al, 2002;Garner et al, 2000;Fan and Rho, 2003). However, testing conditions have not been uniform.…”

Identification of material parameters based on Mohr–Coulomb failure criterion for bisphosphonate treated canine vertebral cancellous bone

“…The unloading segment of the load-displacement curve was analyzed using a mathematical solution derived by Oliver and Pharr [8]. Two sets of elastic modulus and hardness were calculated for each specimen using the CSM method (E CSM and H CSM ) from the loading segment [8,17] and the Oliver-Pharr method (E O-P and H O-P ) from the unloading segment [1,6,8,17], respectively. E CSM and H CSM were averaged from 200 to 500 nm in the modulus-displacement curve and the hardness-displacement curve, respectively, because the initial calculations of modulus and hardness were unstable.…”

“…Nanoindentation has been widely used to study tissue mechanical properties (elastic modulus and hardness) of both cortical [1][2][3] and cancellous bone [4][5][6][7][8]. The method and equations used to calculate bone tissue modulus and hardness in these studies were based on the assumption that the bone was linearly elastic and, therefore, the material properties remained constant independent of the indentation depth [9].…”

Potential for estimation of Young's modulus based on computed tomography numbers in bone: A validation study using a nano-indentation test on murine maxilla

“…It has been indicated that the bone elastic modulus obtained from NI was generally lower under wet conditions than in the dry state [36,[38][39][40]. However, in the previous studies, the samples were first dried, followed by rehydration, after at least 24 hours of immersion in various solutions, such as 3.7% formaldehyde, 4% paraformaldehyde, Ringer's solution, and ethanol.…”