Evidence for an elementary process in bone plasticity with an activation enthalpy of 1 eV

The molecular mechanisms for plastic deformation of bone tissue are not well understood. We analysed temperature and strain-rate dependence of the tensile deformation behaviour in fibrolamellar bone, using a technique originally developed for studying plastic deformation in metals. We show that, bey...

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Bibliographic Details
Published in:Journal of the Royal Society interface 2007-04, Vol.4 (13), p.277-282
Main Authors: Gupta, Himadri S, Fratzl, Peter, Kerschnitzki, Michael, Benecke, Gunthard, Wagermaier, Wolfgang, Kirchner, Helmut O.K
Format: Article
Language:English
Subjects:
Animals
Biomechanical Phenomena
Bone Plasticity
Calcium Mediated Bonds
Cattle
Deformation Mechanisms
Elasticity
Hydrogen Bonding
Micromechanics Of Bone
Periosteum - physiology
Research Article
Temperature
Tensile Strength
Thermal Activation
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Summary:The molecular mechanisms for plastic deformation of bone tissue are not well understood. We analysed temperature and strain-rate dependence of the tensile deformation behaviour in fibrolamellar bone, using a technique originally developed for studying plastic deformation in metals. We show that, beyond the elastic regime, bone is highly strain-rate sensitive, with an activation volume of ca 0.6 nm3. We find an activation energy of 1.1 eV associated with the basic step involved in the plastic deformation of bone at the molecular level. This is much higher than the energy of hydrogen bonds, but it is lower than the energy required for breaking covalent bonds inside the collagen fibrils. Based on the magnitude of these quantities, we speculate that disruption of electrostatic bonds between polyelectrolyte molecules in the extrafibrillar matrix of bone, perhaps mediated by polyvalent ions such as calcium, may be the rate-limiting elementary step in bone plasticity.
ISSN:1742-5689
1742-5662
DOI:10.1098/rsif.2006.0172