TENDINITIS AND TENDON RUPTURE
Inflammatory conditions of the tendons may be acute or chronic. The pathologic reaction is located mainly in the tendon sheath, with tenosynovitis, or paratendinitis.
Chronis inflammation may precipitate varying degrees of degenerative change in the tendon itself, referred to as tendinosis. The latter may be associated with structural weakening and predispose to partial or complete tendon rupture. Rupture can also occur when sufficient force is applied to normal tendons.
A normal tendon is characterized by enormous tensile strength. The crimped, ultrastructural makeup of a tendon means that initial stresses are accommodated by straightening out the crimped arrangements of the collagen fibers. Greater loads stress the fibers themselves. Most day-to-day activity and even stressful sporting maneuvers are accommodated in the toe region and early in the linear phase of the stress strain curve for tendon. The linear phase represents ligamentous elasticity, and deformation is reversible. At the high ends of functional loading, plastic deformation and even microfailure may occur.