Inflammation vs. Degeneration
The term Achilles tendonitis should be used to refer to inflammation of the Achilles tendon. Inflammation is most often an acute change (the result of a sudden injury). This problem is characterized by swelling, redness, warmth, and pain. When seen under the microscope, inflammatory conditions have specific cells that the body brings to that area of the body to help control the inflammation and heal the injured tendon.Achilles tendinosis is a different condition that is not characterized by inflammation. Rather, these patients have thickening of the tendon. There is usually no redness or warmth of the surrounding soft tissues, although the area can be painful to touch. Achilles tendinosis is a chronic problem, meaning it develops gradually and lasts a long time. When seen under a microscope, inflammatory cells are not present, although chronic damage and microscopic tears of the tendon may be seen.
Treatment of Achilles Tendinosis
While the treatment of Achilles tendonitis and Achilles tendinosis is similar, it is not the same. It is important to note that because Achilles tendinosis lacks inflammation, treatments that are aimed at controlling inflammation are unlikely to be helpful. Therefore, while anti-inflammatory medications and ice application may be used to treat symptoms of discomfort associated with Achilles tendinosis, they are not fighting inflammation in this situation. The more effective treatments for Achilles tendinosis tend to be shoe inserts, therapeutic exercises, and stretching.Sources:
Saltzman CL, Tearse DS. "Achilles tendon injuries" J. Am. Acad. Ortho. Surg., Sep 1998; 6: 316 - 325.

