Due to:
-ruptured fibers can no longer sustain load, increased loads placed on neighboring fibers, making them more susceptible to rupture
-disruption of tendons also lead to disruption of blood supply, inducing ischemia
-disrupted tendon fibers are exposed to joint fluid, which has a lytic effect on tendons, disrupting healing process
-scar tissue that replaces tendon fibers does not have same tensile length, increasing risk of failure
-once FTT, loads that are normally distributed through entire intact tendon are transmitted at torn margin which produces a "zipper" effect and unzips/extends tendon from tuberosity