Tendinopathy is the medical term for injury, pathologic change, or damage to a tendon. There may be a thickening of the tissue or irregular tendon structure. With Achilles' tendinopathy, there is usually swelling, tenderness or pain, and decreased function of the Achilles' tendon.

Sometimes this condition is referred to insertional Achilles tendinopathy. The pain and tenderness occur right at the point where the tendon inserts into the bone. When the main body of the tendon is tender, it is called paratendinopathy.

The diagnosis of Achilles' tendinopathy is usually made by examination and imaging studies. Plain X-rays and ultrasound pictures help rule out other conditions such as bursitis or bone spurs.