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Measurement of microstructural strain in cortical bone
Daniel P Nicolella1, Lynda F Bonewald, Donald E Moravits
1Mechanical and Materials Engineering Division, Southwest Research Institute, San Antonio, TX 78238, USA. dnicolella@swri.org
European Journal of Morphology
|August 27, 2005
Summary
Bone matrix strains around osteocytes are amplified significantly during mechanical loading, potentially explaining how bone cells sense and respond to functional demands. This micro-level strain amplification may precede microdamage formation.
Area of Science:
- Biomechanics
- Cellular Biology
- Orthopedics
Background:
- Mechanical factors critically influence bone remodeling, with higher demand promoting bone formation and lower demand leading to resorption.
- Osteocytes are believed to mediate cellular-level signals controlling bone modeling and remodeling in response to mechanical stimuli.
Purpose of the Study:
- To investigate the manifestation of macroscopic bone strains at the microscopic level within the bone matrix.
- To quantify bone matrix strains around osteocyte lacunae under in vivo-relevant macroscopic strains.
Main Methods:
- Utilized digital image correlation (DIC) strain measurement technique.
- Applied macroscopic bone strains of approximately 2,000 microstrain (0.2%).
- Measured bone matrix strains at the microscopic level around osteocyte lacunae.
Main Results:
- Macroscopic strains of ~2,000 microstrain induced bone matrix strains exceeding 30,000 microstrain (3%) around osteocyte lacunae—over 15 times the applied load.
- Observed highly heterogeneous strain patterns within the bone matrix.
- Identified strain patterns resembling precursors to microdamage around osteocyte lacunae.
Conclusions:
- Macroscopic bone loading results in significant mechanical strain amplification at the osteocyte lacuna level.
- These amplified, heterogeneous micro-strains may be critical signals for osteocytes, influencing bone cell behavior and potentially leading to microdamage.
- Findings enhance understanding of mechanotransduction in bone and its implications for bone health and disease.