Effect of micromorphology of cortical bone tissue on crack propagation under dynamic loading

Abstract

Abstract. Structural integrity of bone tissue plays an important role in daily activities of humans. However, traumatic incidents such as sports injuries, collisions and falls can cause bone fracture, servere pain and mobility loss. In addition, ageing and degenerative bone diseases such as osteoporosis can increase the risk of fracture [1]. As a composite-like material, a cortical bone tissue is capable of tolerating moderate fracture/cracks without complete failure. The key to this is its heterogeneously distributed microstructural constituents providing both intrinsic and extrinsic toughening mechanisms. At micro-scale level, cortical bone can be considered as a four-phase composite material consisting of osteons, Haversian canals, cement lines and interstitial matrix. These microstructural constituents can directly affect local distributions of stresses and strains, and, hence, crack initiation and propagation. Therefore, understanding the effect of micromorphology of cortical bone on crack initiation and propagation, especially under dynamic loading regimes is of great importance for fracture risk evaluation. In this study, random microstructures of a cortical bone tissue were modelled with finite elements for four groups: healthy (control), young age, osteoporosis and bisphosphonate-treated, based on osteonal morphometric parameters measured from microscopic images for these groups. The developed models were loaded under the same dynamic loading conditions, representing a direct impact incident, resulting in progressive crack propagation. An extended finite-element method (X-FEM) was implemented to realize solution-dependent crack propagation within the microstructured cortical bone tissues. The obtained simulation results demonstrate significant differences due to micromorphology of cortical bone, in terms of crack propagation characteristics for different groups, with the young group showing highest fracture resistance and the senior group the lowest.

A heterogeneous orientation criterion for crack modelling in cortical bone using a phantom-node approach

“…Similar fracture paths were obtained in [30] accounting also for the effect of age in the porosity of the bone. Analogous results have been obtained by other authors [31][32][33], without obtaining a realistic path. The above references applied fracture criteria initially conceived for homogeneous material.…”

Prevalent role of porosity and osteonal area over mineralization heterogeneity in the fracture toughness of human cortical bone

“…4B) using an interactive tablet monitor (Wacom Technology Co., Vancouver, WA). Manual segmentation is commonly used to distinguish osteonal from interstitial tissue (Bernhard et al, 2013; Tommasini et al, 2008; Wachter et al, 2002; Wang et al, 2015) and increasing the image contrast for this step made the segmentation unambiguous. Area fraction of osteonal tissue ( OstAr ) with respect to the total area of the sub-region was computed for each sub-region.…”

Whole Body Mechanical Vibrations of Passengers Travelling in Busses in Sri Lanka

“…When the vibrations occur on the floor of the buss the vibrational energy get transferred into the tissues of the passengers and some of them get absorbed into the tissues and the rest makes the tissue vibrations [6]. The part absorbed into the tissue results developing and aggravating micro cracks in the bones [3,4,5] ,tissue plastic deformations and heat due to friction. Proper resting is required to get back to the original stage of the tissue [3,4,5].…”

“…The part absorbed into the tissue results developing and aggravating micro cracks in the bones [3,4,5] ,tissue plastic deformations and heat due to friction. Proper resting is required to get back to the original stage of the tissue [3,4,5]. The permissible level of exposure depend upon the frequency values and the Figure 6.0 shows the vertical permissible exposure durations with different frequencies of exposure.…”

“…In addition, these standards clearly indicate proper resting is required for the body and the bones to recover and remodeled themselves after undergoing severe whole body vibration exposure. Also if the proper resting or remodeling of the bones does not happen, it could leads to aggravation and propagation of the micro cracks and could even results in bone fatigue (depend on the strain and strain frequencies) and cartilage damages [3,4,5]. In addition to the health effects other adverse side effects results in exposure to a high dosage of whole body vibrations are decreased performance levels, temporary threshold shifts, reduce motion control, impaired vision, discomfort and fatigue decreased job proficiency.…”