An Automated Step-Wise Micro-Compression Device for 3D Dynamic Image-Guided Failure Assessment of Bone Tissue on a Microstructural Level Using Time-Lapsed Tomography

Abstract

Microstructural bone phenotypes, such as the intracortical canal network, could be directly linked to the mechanical failure behavior of cortical bone tissue. In addition, high accumulation of microdamage can significantly increase bone brittleness and thus, is a precursor of mechanical failure. Here, we discuss the development and validation of an automated step-wise micro-compression device (MCD) for dynamic image-guided failure assessment (DIGFA) of intracortical bone microstructure and bone microdamage. The device was found to be highly accurate and precise with positioning errors of less than 1 µm and force errors of less than 1.25 N. In addition, the results of a first biological study using DIGFA and time-lapsed computed tomography are presented. In short, whole mouse femora from mature C57BL/6 (B6) and C3H/He (C3H) mice with mid-diaphyseal notches were tested in step-wise compression and concomitantly imaged until failure. DIGFA was performed at the TOMCAT beamline of the Swiss Light Source (SLS) using synchrotron radiation-based computed tomography (SR CT). Following the experiment, intracortical porosity was separated into the canal network, osteocyte lacunae, and microcracks for subsequent morphometric evaluation. The thicker cortex of C3H was penetrated by a dense canal network, whereas in B6 only a few scattered canals were observed. For B6, the first occurrence of crack was noted at 1.45% local strain, while for C3H, crack initiation took place only at 2.66% local strain. In addition, we were able to relate whole bone mechanics to local failure events by deriving correlations between microstructural porosity and microdamage propagation. In conclusion, initiation and accumulation of microcracks were investigated for two mouse phenotypes demonstrating that DIGFA in combination with SR CT is a suitable technique for time-lapsed three-dimensional assessment of bone morphology and bone fracture behavior down to the cellular level.

Large-scale quantification of human osteocyte lacunar morphological biomarkers as assessed by ultra-high-resolution desktop micro-computed tomography

“…The range of considered object volumes was also important for lacunar identification. This range varies substantially between studies and could be as narrow as 50-610µm 3 or as wide as 175-2000µm 3 [18,21,42,43,51,52]. Previous examinations of histological slides have estimated the human lacunae to be between 28µm 3 and 1713µm 3 , yet lacunae observed below 50µm 3 were only found in fracture callus [41].…”

Mechano-Regulation of Trabecular Bone Adaptation Is Controlled by the Local in vivo Environment and Logarithmically Dependent on Loading Frequency

“…We have previously imaged mouse caudal vertebrae subjected to cyclic loading at 10 Hz using high-resolution micro-CT (1.2 μm) and could not detect any micro-damage at the local level, and therefore, we do not expect the lower frequencies to cause local micro-damage either. Nevertheless, the incorporation of techniques to visualize bone micro-damage—ranging from 2D histology and 3D micro-CT imaging ( Poundarik and Vashishth, 2015 ) to more advanced methods such as an automated step-wise micro-compression device for dynamic image-guided failure ( Levchuk et al, 2018 ) —could provide novel insight into the initiation and propagation of micro-damage in response to cyclic loading in trabecular mouse bone.…”

Correlating Local Volumetric Tissue Strains with Global Lung Mechanics Measurements

“…The use of image correlation methods like DVC is widespread in the field of biomechanics in hard and soft tissues [ 14 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 ]. The accuracy and physiological relevance of X-ray irradiated biomaterials (ex vivo) is consistently challenged and assessed, e.g., [ 24 ].…”