Linking multiscale deformation to microstructure in cortical bone using in situ loading, digital image correlation...

Area of Science:

• Biomaterials Science
• Orthopedic Research
• Materials Science

Background:

• Fragility fractures are increasing due to aging populations, necessitating improved fracture prediction tools.
• Understanding bone deformation mechanisms across multiple length scales is crucial for developing effective prevention and treatment strategies.

Purpose of the Study:

• To investigate bone deformation mechanisms at tissue and nanoscale levels.
• To elucidate the relationship between bone microstructure orientation and mechanical response under tensile loading.
• To assess the potential of combining advanced experimental techniques for comprehensive bone fracture analysis.

Main Methods:

• Mechanical tensile testing combined with digital image correlation (DIC).
• Small/wide-angle X-ray scattering (SAXS/WAXS) for nanoscale deformation analysis.
• Micro-computed tomography (micro-CT) for detailed tissue microstructure imaging.

Main Results:

• Microstructure orientation significantly influences strain magnitude at all length scales.
• Collagen fiber strains were 2-3 times higher than mineral crystal strains when microstructure was parallel to loading.
• Local tissue strain at fracture was approximately 0.5%, irrespective of orientation, but maximum force and crack path irregularity increased with parallel loading.

Conclusions:

• Combining mechanical testing with DIC, SAXS/WAXS, and micro-CT provides multi-scale insights into bone deformation and fracture.
• Bone microstructure plays a critical role in mechanical behavior and fracture patterns.
• This multi-technique approach enhances understanding of structure-property-function relationships in bone tissue, vital for predicting fragility fractures.