Micro-mechanical properties of the tendon-to-bone attachment

Alix C. Deymier, Yiran An, John J. Boyle, Andrea G. Schwartz, Victor Birman, Guy M. Genin, Asa Barber, Stavros Thomopoulos

    Research output: Contribution to journalArticlepeer-review

    80 Downloads (Pure)

    Abstract

    The tendon-to-bone attachment (enthesis) is a complex hierarchical tissue that connects stiff bone to compliant tendon. The attachment site at the micrometer scale exhibits gradients in mineral content and collagen orientation, which likely act to minimize stress concentrations. The physiological microme- chanics of the attachment thus define resultant performance, but difficulties in sample preparation and mechanical testing at this scale have restricted understanding of structure-mechanical function. Here, microscale beams from entheses of wild type mice and mice with mineral defects were prepared using cryo-focused ion beam milling and pulled to failure using a modified atomic force microscopy system. Micromechanical behavior of tendon-to-bone structures, including elastic modulus, strength, resilience, and toughness, were obtained. Results demonstrated considerably higher mechanical performance at the micrometer length scale compared to the millimeter tissue length scale, describing enthesis material properties without the influence of higher order structural effects such as defects. Micromechanical investigation revealed a decrease in strength in entheses with mineral defects. To further examine structure-mechanical function relationships, local deformation behavior along the tendon-to-bone attachment was determined using local image correlation. A high compliance zone near the mineralized gradient of the attachment was clearly identified and highlighted the lack of correlation between mineral distribution and strain on the low-mineral end of the attachment. This compliant region is proposed to act as an energy absorbing component, limiting catastrophic failure within the tendon-to-bone attach- ment through higher local deformation. This understanding of tendon-to-bone micromechanics demon- strates the critical role of micrometer scale features in the mechanics of the tissue.
    Original languageEnglish
    JournalActa Biomaterialia
    Early online date11 Jan 2017
    DOIs
    Publication statusEarly online - 11 Jan 2017

    Keywords

    • enthesis
    • micromechanics
    • image correlation
    • tensile testing
    • gradient
    • AFM

    Fingerprint

    Dive into the research topics of 'Micro-mechanical properties of the tendon-to-bone attachment'. Together they form a unique fingerprint.

    Cite this