Achilles tendinitis exists along the spectrum of peritendinitis to tendinosis or tendinopathy. This is a painful, swollen, and tender area of the Achilles tendon and peritenon usually secondary to repetitive activity or overuse.
Athletes with particularly tight heel cords are predisposed to injury. This condition commonly affects middle-aged men who play tennis, basketball, or other quick start-and-stop sports. Collagen vascular disease and diabetes may also be risk factors.
The two main categories of Achilles tendon disorder are broadly classified by anatomical location to include non-insertional and insertional conditions.