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Probing multi-scale mechanical damage in connective tissues using x-ray diffraction

DOI: 10.1016/j.actbio.2016.08.027 DOI Help

Authors: Fabio Bianchi (Department of Engineering Science, University of Oxford) , Felix Hofmann (Department of Engineering Science, University of Oxfor) , Andrew J. Smith (Diamond Light Source) , Mark S. Thompson (Department of Engineering Science, University of Oxford)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Acta Biomaterialia

State: Published (Approved)
Published: August 2016
Diamond Proposal Number(s): 10601

Abstract: The accumulation of microstructural collagen damage following repetitive loading is linked to painful and debilitating tendon injuries. As a hierarchical, semi-crystalline material, collagen mechanics can be studied using x-ray diffraction. The aim of the study was to describe multi-structural changes in tendon collagen following controlled plastic damage (5% permanent strain). We used small angle x-ray scattering (SAXS) to interrogate the spacing of collagen molecules within a fibril, and wide angle x-ray scattering (WAXS) to measure molecular strains under macroscopic loading. Simultaneous recordings of of SAXS and WAXS patterns, together with whole-tissue strain in physiologically hydrated rat-tail tendons were made during increments of in-situ tensile loading. Results showed that while tissue level modulus was unchanged, fibril modulus decreased significantly, and molecular modulus significantly increased. Further, analysis of higher order SAXS peaks suggested structural changes in the gap and overlap regions, possibly localising the damage to molecular cross-links. Our results provide new insight into the fundamental damage processes at work in collagenous tissues and point to new directions for their mitigation and repair.

Journal Keywords: Tendon; Collagen; X-Ray Diffraction; Damage

Subject Areas: Biology and Bio-materials, Medicine

Instruments: I22-Small angle scattering & Diffraction