[Back]


Publications in Scientific Journals:

P. J. Thurner, B. Erickson, Z. Schriock, R. Jungmann, J. Weaver, G. Fantner, G. Schitter, D. Morse, P.K. Hansma:
"High-Speed photography of compressed human trabecular bone correlates whitening to microscopic damage";
Engineering Fracture Mechanics (invited), 74 (2006), 12; 1928 - 1941.



English abstract:
Mechanical testing of trabecular bone is mainly motivated by the huge impact of osteoporosis in post-menopausal
women and the aged in society in terms of social and health care costs. Trabecular bone loss and impairment of its mechanical
properties reduce bone strength and increase fracture risk, especially in vertebrae. It is generally accepted that in addition
to bone mineral density, microarchitecture and material properties of bone also play important roles for bone strength
and fracture risk. In order to overcome the limitations of standard mechanical tests delivering merely integral information
about complicated samples, experiments were designed for step-wise mechanical testing with concurrent imaging of trabecular
and cortical bone. In this communication we present an approach for real-time imaging of trabecular bone during
compression using high-speed photography and investigate the hypothesis whether the whitening of deformed trabeculae
is due to microdamage. Experiments on human trabecular bone samples from a healthy male donor revealed that failure of
such samples is highly localized in fracture bands. Moreover, strongly deformed trabeculae were seen to whiten, an effect
similar to stress whitening in polymers. Scanning Electron Microscopy of the same regions of interest revealed that whitened
trabeculae were strongly damaged by microscopic cracks and mostly failed in delamination. Higher resolution images
uncovered mineralized collagen fibrils spanning the cracks. The whitening partially faded after unloading of the samples,
presumably due to partial crack closure. Overall, high-speed photography enables microdamage detection in real-time during
a mechanical test and provides a correlation to recorded stress strain curves.

Keywords:
Trabecular bone; Fracture; High-speed photography; Stress-whitening; Microdamage; Delamination

Created from the Publication Database of the Vienna University of Technology.