title: Effect of high-energy X-ray doses on bone elastic properties and residual strains.
abstract: Bone X-ray irradiation occurs during medical treatments, sterilization of allografts, space travel and in vitro studies. High doses are known to affect the post-yield properties of bone, but their effect on the bone elastic properties is unclear. The effect of such doses on the mineral-organic interface has also not been adequately addressed. Here, the evolution of elastic properties and residual strains with increasing synchrotron X-ray dose (5-3880 kGy) is examined on bovine cortical bone. It is found that these doses affect neither the degree of nanometer-level load transfer between the hydroxyapatite (HAP) platelets and the collagen up to stresses of -60 MPa nor the microscopic modulus of collagen fibrils (both measured by synchrotron X-ray scattering during repeated in situ loading and unloading). However, the residual elastic strains in the HAP phase decrease markedly with increased irradiation, indicating damage at the HAP-collagen interface. The HAP residual strain also decreases after repeated loading/unloading cycles. These observations can be explained by temporary de-bonding at the HAP/collagen interface (thus reducing the residual strain), followed by rapid re-bonding (so that load transfer capability is not affected).
authors.affiliation: Department of Materials Science and Engineering, 2220 Campus Drive, Northwestern University, Evanston, IL 60208, USA. AnjaliSinghal2007@u.northwestern.edu
authors.forename: A
authors.initials: A
authors.lastname: Singhal
authors.forename: Alix C
authors.initials: AC
authors.lastname: Deymier-Black
authors.forename: J D
authors.initials: JD
authors.lastname: Almer
authors.forename: D C
authors.initials: DC
authors.lastname: Dunand
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D002417:Cattle; D004307:Dose-Response Relationship, Radiation; D017886:Durapatite / Q000737:chemistry / Q000378:metabolism; D055119:Elastic Modulus / Q000528:radiation effects; D004548:Elasticity / Q000528:radiation effects*; D005269:Femur / Q000378:metabolism / Q000528:radiation effects*; D013314:Stress, Mechanical; D014965:X-Rays / Q000009:adverse effects
chemical_list: D017886:Durapatite