Understanding the biomechanics of tendon fibrocartilages.

A direct analogy with the function of large proteoglycans in articular cartilage has led to the assumption that the presence of such components in tendon fibrocartilages is a major factor enabling these structures to resist pressure. However, the association of collagen fibrils in bundles and their tensional state as verified through the existence of crimp under polarized light in tendon fibrocartilage raises doubts as to whether the large proteoglycans are kept under osmotic pressure, which is an essential condition for their physiological role in articular cartilage. This suggests that tendon fibrocartilage has distinct mechanisms to resist pressure. In tendon fibrocartilages, the compressive forces must be transferred to the inextensible collagen fibers which lie in many directions in different planes, before reaching the parallel fibers of the tension region. In this sense, the large proteoglycans are likely to have the function of providing a viscous and cohesive environment in which collagen fibers could get stretched to reinforce the tissue.