Differences in the Crack Resistance of Interstitial, Osteonal and Trabecular Bone Tissue

Abstract

The purpose of this work was to investigate differences which may exist in the crack resistance of the microstructural bone tissues, i.e., osteonal, interstitial and trabecular bone. Indentations, using varying loads were used to initiate cracks of the same size scale as those which exist habitually in bone. The crack lengths and corresponding toughness values are presented for each of the tissues. Specimens were prepared using standard nanoindentation preparation techniques. Young's modulus and hardness were measured using a Berkovich tip, while cracks were produced using a cube-corner tip. Crack lengths were subsequently measured using scanning electron microscopy. Cracks produced at the same loads were significantly longer in trabecular bone than in interstitial and osteonal cortical bone. Similarly, within individual subjects, cracks produced in interstitial bone were longer than those produced in osteonal bone. These results provide significant experimental evidence that bone microstructural tissues exhibit differing resistance to crack growth and may help explain the incidence of more microcracks in interstitial than osteonal bone. The ability of the technique to distinguish differences between individual bone tissues is promising in an area where the focus has switched to the microscale, and in particular, to measures bone quality.

Effects of Moisture Content and Loading Profile on Changing Properties of Bone Micro-Biomechanical Characteristics

“…Bone is a connective tissue mainly composed of mineral and type I collagen, which determines the hardness and strength of bones [ 16 , 17 ]. Micro-indentation and ultrasound techniques have been used to determine the hardness and strength of bones [ 18 , 19 ].…”

Spatial variation in osteon population density at the human femoral midshaft: histomorphometric adaptations to habitual load environment

“…cement lines) help to attenuate energy of microdamage, thereby restricting propagation (Gibson et al 2006). Indeed, Mullins et al (2006) have demonstrated that the severity of microdamage, as measured by crack length, is much greater in areas of interstitial bone and much less severe in areas of osteonal bone. Therefore, higher remodeling density found in the anterolateral femoral cortex in this study might be evidence of an adaptive toughening mechanism in response to habitual tension/shear loading in this region to reduce the severity of microdamage experienced.…”

Micro-scale modelling of bovine cortical bone fracture: Analysis of crack propagation and microstructure using X-FEM

“…The effect of bone quantity on the mechanical behaviour and structural integrity of bone was established previously [5,6], however, more in-depth investigations are still required of the contributory effects of microstructure, material properties, and microcrack propagation [3,7]. These can be characterized as bone quality measures; an improved understanding of bone quality, particularly, resistance to crack initiation and propagation can help in accessing bone fracture risk [8]. It is well known that damage occurs in both trabecular and cortical bone due to daily activity loading regime [9].…”

“…Evolution of damage in our models is defined based on the energy required for failure (fracture energy) after the initiation of damage. The stress intensity factor for the homogenised material is based on data from Nalla et al [30], and those for osteons and interstitial bone were taken by guidance from [8]. A ratio, ⁄ = 2 where and are interstitial bone and cement line stress intensity factors, were utilized to obtain the cement line stress intensity factor based on [31].…”