Characterizing local collagen fiber re-alignment and crimp behavior throughout mechanical testing in a mature mouse supraspinatus tendon model

J Biomech. 2012 Aug 9;45(12):2061-5. doi: 10.1016/j.jbiomech.2012.06.006. Epub 2012 Jul 8.


Background: Collagen fiber re-alignment and uncrimping are two postulated mechanisms of tendon structural response to load. Recent studies have examined structural changes in response to mechanical testing in a postnatal development mouse supraspinatus tendon model (SST), however, those changes in the mature mouse have not been characterized. The objective of this study was to characterize collagen fiber re-alignment and crimp behavior throughout mechanical testing in a mature mouse SST.

Method of approach: A tensile mechanical testing set-up integrated with a polarized light system was utilized for alignment and mechanical analysis. Local collagen fiber crimp frequency was quantified immediately following the designated loading protocol using a traditional tensile set up and a flash-freezing method. The effect of number of preconditioning cycles on collagen fiber re-alignment, crimp frequency and mechanical properties in midsubstance and insertion site locations were examined.

Results: Decreases in collagen fiber crimp frequency were identified at the toe-region of the mechanical test at both locations. The insertion site re-aligned throughout the entire test, while the midsubstance re-aligned during preconditioning and the test's linear-region. The insertion site demonstrated a more disorganized collagen fiber distribution, lower mechanical properties and a higher cross-sectional area compared to the midsubstance location.

Conclusions: Local collagen fiber re-alignment, crimp behavior and mechanical properties were characterized in a mature mouse SST model. The insertion site and midsubstance respond differently to mechanical load and have different mechanisms of structural response. Additionally, results support that collagen fiber crimp is a physiologic phenomenon that may explain the mechanical test toe-region.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Collagen / chemistry*
  • Collagen / metabolism*
  • Mice
  • Models, Biological*
  • Stress, Physiological / physiology*
  • Tendons / physiology*
  • Weight-Bearing / physiology


  • Collagen