Mechanical Properties and Fracture Behavior of Cortical Bone

Cortical bone is a hierarchical, anisotropic composite that provides structural support and protection in vertebrate skeletons. Its mechanical properties—elastic modulus, strength and toughness—result from the organised arrangement of mineralised collagen fibrils, osteons and interstitial lamellae. Fracture behaviour is governed by mechanisms at multiple scales: nanoscale collagen sliding and sacrificial bonds, microscale crack deflection at cement lines and osteon boundaries, and macroscale crack bridging and microcracking. These processes collectively dissipate energy, control crack initiation and arrest crack propagation. Factors such as age, disease, temperature and loading orientation influence stiffness, yield strength and post-yield ductility. Advances in imaging, in situ mechanical testing and computational modelling have deepened understanding of the interplay between bone’s microarchitecture and fracture resistance. This knowledge underpins improvements in clinical diagnostics, biomimetic material design and injury prevention strategies.

Research from Nature Portfolio

Recent studies have demonstrated that nanoscale damage to collagen networks markedly reduces bone toughness and alters microscale toughening. In situ synchrotron microtomography combined with deep-learning image processing has revealed that heat-induced collagen damage diminishes crack deflection around microstructural features, leading to lower macroscale fracture energy and reduced post-yield properties. This work highlights the critical role of intact collagen at multiple scales in maintaining cortical bone resilience.

High-resolution three-dimensional X-ray imaging of fossilised bone microarchitecture has uncovered novel porosity patterns previously undetected in two dimensions. The detailed mapping of vascular channels and trabecular struts in pterosaur cortex offers insights into natural design strategies for lightweight yet tough materials. Such palaeo-inspired microarchitectures are now being reverse-engineered to guide the development of self-healing synthetic composites with embedded monitoring capabilities.

Mechanical Properties and Fracture Behavior of Cortical Bone publication trend

The graph below shows the total number of articles in mechanical properties and fracture behavior of cortical bone across all publications each year (not limited to Nature Index journals).

Technical terms

Cortical bone: The dense outer layer of bone tissue composed of osteons and interstitial lamellae, responsible for stiffness and resistance to bending.

Fracture toughness: A measure of a material’s ability to resist crack propagation, reflecting energy dissipation mechanisms.

Osteon: A cylindrical microstructural unit in cortical bone, comprising concentric lamellae around a central canal.

Cement line: The interface between an osteon and surrounding interstitial bone, often acting as a crack-deflecting boundary.

Continuum damage mechanics: A theoretical framework describing the progressive degradation of material stiffness and strength due to microdamage accumulation.

Stress triaxiality: The ratio of hydrostatic stress to von Mises equivalent stress, influencing the mode and onset of fracture under complex loading.

References

1. Unraveling the effect of collagen damage on bone fracture using in situ synchrotron microtomography with deep learning. Communications Materials (2022).
2. Harnessing 3D microarchitecture of pterosaur bone using multi-scale X-ray CT for aerospace material design. Scientific Reports (2025).
3. Cortical bone continuum damage mechanics constitutive model with stress triaxiality criterion to predict fracture initiation and pattern. Frontiers in Bioengineering and Biotechnology (2022).
4. Crack propagation in cortical bone is affected by the characteristics of the cement line: a parameter study using an XFEM interface damage model. Biomechanics and Modeling in Mechanobiology (2019).
5. Mechanical properties of cortical bones related to temperature and orientation of Haversian canals. Materials Research Express (2020).
6. A Review on Multiscale Bone Damage: From the Clinical to the Research Perspective. Materials (2021).