It Is Frequently Confused with Tendinopathy
Achilles tendonitis and Achilles tendinopathy are sometimes used interchangeably in some spaces. Both conditions are caused by overuse or sudden stress on the Achilles tendon, but they are not the same thing. Tendonitis is an inflammation of the tendons while tendinopathy is a breakdown of the collagen protein the tendon is made of. There is little to no inflammation in tendinopathy.
Aside from this misunderstanding, doctors used to think tendonitis eventually progressed into tendinopathy. On the contrary, new evidence suggests that tendonitis may be the eventual result of tendinopathy. [4]
Although the term tendonitis is more common, tendinopathy affects more people.