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Sensitivity of multiple damage parameters to compressive overload in cortical bone.
Elise F Morgan1, John J Lee, Tony M Keaveny
1Orthopedic Biomechanics Laboratory, Department of Mechanical Engineering, University of California, Berkeley, CA 94720, USA. efmorgan@bu.edu
Journal of Biomechanical Engineering
|August 27, 2005
Summary
Bone mechanical properties degrade after overload. Strength and Poisson's ratio change more than elastic modulus, suggesting modulus is less sensitive to damage in cortical bone.
Area of Science:
- Biomechanics
- Materials Science
- Orthopedics
Background:
- Damage accumulation weakens bone before fracture.
- Bone remodeling is stimulated by damage.
- Understanding mechanical property degradation is crucial for bone health.
Purpose of the Study:
- Characterize mechanical property changes in cortical bone after compressive overload.
- Identify which mechanical properties are most sensitive to overload-induced damage.
Main Methods:
- Tested 24 bovine cortical bone specimens using an overload-hold-reload protocol.
- Applied compressive overload to induce damage.
- Measured changes in elastic modulus, strength, Poisson's ratio, and residual strains.
Main Results:
- Elastic modulus showed minimal reduction (<5%) for strains <0.73%.
- Strength and Poisson's ratio changes were significantly greater than modulus changes.
- Residual strains were disproportionately larger in the transverse than axial direction.
Conclusions:
- Longitudinal elastic modulus is a less sensitive indicator of compressive overload damage in cortical bone.
- Strength and Poisson's ratio are more sensitive to microdamage.
- Consider alternative parameters beyond modulus for relating microcracks to mechanical property changes.