Tendon also have a role in the tensile properties of tendon. The structure of tendon is effectively a fibre composite material, built as a series of hierarchical levels. At each level of the hierarchy, the collagen units are bound together by either collagen crosslinks, or the proteoglycans, to create a structure highly resistant to tensile load. The elongation and the strain of the collagen fibrils alone have been shown to be much lower than the total elongation and strain of the entire tendon under the same amount of stress, demonstrating that the proteoglycan-rich matrix must also undergo deformation, and stiffening of
Achilles tendon rupture to rupture. The use of quinolone antibiotics can cause several forms of tendinitis and tendon rupture, including rupture of the Achilles tendon. The risk is higher in people who are older than 60, who are also taking corticosteroids, or have kidney disease; it also increases with dose and taking them for longer periods of time. As of 2016 the mechanism through which quinolones cause this, was unclear. The Achilles tendon is the strongest and thickest tendon in the body, connecting the gastrocnemius, soleus and plantaris to the calcaneus. It is approximately 15 centimeters (5.9 inches) long and begins near the