Recruitment of Tendon Crimp with Applied Tensile Strain

Abstract

The stress-strain behavior of ligaments and tendons begins with a toe region that is believed to result from the straightening of crimped collagen fibrils. Their physiological function is mostly confined to this toe region and changes in crimp morphology are believed to be associated with pathological conditions. A relatively new imaging technique, optical coherence tomography (OCT), provides a comparatively inexpensive method for nondestructive investigation of tissue ultrastructure with resolution on the order of 15 μm and the potential for use in a clinical setting. The objectives of this work were to measure the period of crimp pattern in rat tail tendon fascicles, and to measure changes in crimp period as a function of tensile strain using OCT. Fascicles from rat tail tendons were subjected to 0.5% strain increments up to 5% and imaged at each increment using OCT. The OCT images corresponded well to OM images taken between crossed polarizing lenses. Crimp pattern disappeared completely at strains below 3%, first near the surface of the fascicle and finally at the center. Average crimp period increased as strain increased, but individual, axially aligned periods increased and decreased due to non-uniform recruitment of crimp.