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The microstructure and micromechanics of the tendon–bone insertion

Nature Materials volume 16, pages 664670 (2017) | Download Citation

Abstract

The exceptional mechanical properties of the load-bearing connection of tendon to bone rely on an intricate interplay of its biomolecular composition, microstructure and micromechanics. Here we identify that the Achilles tendon–bone insertion is characterized by an interface region of 500 μm with a distinct fibre organization and biomolecular composition. Within this region, we identify a heterogeneous mechanical response by micromechanical testing coupled with multiscale confocal microscopy. This leads to localized strains that can be larger than the remotely applied strain. The subset of fibres that sustain the majority of loading in the interface area changes with the angle of force application. Proteomic analysis detects enrichment of 22 proteins in the interfacial region that are predominantly involved in cartilage and skeletal development as well as proteoglycan metabolism. The presented mechanisms mark a guideline for further biomimetic strategies to rationally design hard–soft interfaces.

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Acknowledgements

Research was supported by the International Graduate School of Science and Engineering (L.R. and L.A.K.). The authors acknowledge the continuous support of the DFG via the Nanosystems Initiative Munich (NIM).

Author information

Author notes

    • L. Rossetti
    •  & L. A. Kuntz

    These authors contributed equally to this work.

Affiliations

  1. Lehrstuhl für Zellbiophysik, Technische Universität München, D-85748 Garching, Germany

    • L. Rossetti
    • , L. A. Kuntz
    • , H. Grabmayr
    •  & A. R. Bausch
  2. Klinik für Orthopädie und Sportorthopädie, Klinikum rechts der Isar, Technische Universität München, D-81675 München, Germany

    • L. A. Kuntz
    • , J. Stolberg-Stolberg
    •  & R. Burgkart
  3. Center for Integrated Protein Science (CIPSM), Department of Chemistry, Technische Universität München, D-85747 Garching, Germany

    • E. Kunold
    •  & S. A. Sieber
  4. Lehrstuhl für Biomedizinische Physik, Physik-Department & Institut für Medizintechnik, Technische Universität München, D-85748 Garching, Germany

    • J. Schock
    •  & F. Pfeiffer
  5. Institute for Computational Mechanics, Technische Universität München, D-85748 Garching, Germany

    • K. W. Müller
  6. Structural and Applied Mechanics Group, Computational Engineering Division, Lawrence Livermore National Laboratory, 7000 East Ave, Livermore, California 94550, USA

    • K. W. Müller
  7. Department of Physics and Center for Nanoscience, Ludwig Maximilian University, D-80539 Munich, Germany

    • H. Grabmayr
  8. University Hospital Münster, Department of Trauma-, Hand- and Reconstructive Surgery, Albert-Schweitzer-Campus 1, Building W1, D-48149 Münster, Germany

    • J. Stolberg-Stolberg
  9. Institut für diagnostische und interventionelle Radiologie, Klinikum rechts der Isar, Technische Universität München, D-81675 München, Germany

    • F. Pfeiffer

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Contributions

L.R. and L.A.K. contributed equally to this work. L.R., L.A.K., H.G., J.S.-S., F.P., S.A.S., R.B. and A.R.B. designed the research. L.A.K. and J.S. performed microcomputed tomography. L.R. and L.A.K. carried out micromechanical analysis, confocal microscopy and investigated fibre composition. L.A.K. and E.K. performed proteomics experiments. L.R., L.A.K., K.W.M., R.B. and A.R.B. analysed the data and wrote the paper. All authors reviewed and revised the manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding authors

Correspondence to R. Burgkart or A. R. Bausch.

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DOI

https://doi.org/10.1038/nmat4863