Tendinosis refers to intratendinous degeneration from a previous longitudinal tear without an inflammatory response. Partial and complete tendon ruptures are usually easy to differentiate from each other clinically. Achilles tendon problems are particularly common in runners, and running accounts for more than ten percent of Achilles tendon injuries. Aging, poor training technique and anatomic abnormalities can contribute to Achilles tendon morbidity. In paratenonitis, the patient typically shows a gradual onset of pain, swelling and warmth localized in the Achilles tendon area.
More advanced cases can present symptoms when performing normal activities or while at rest.
Achilles tendinosis is also common and presents as a palpable tendon nodule that may or may not be associated with swelling and signs of inflammation. Tendinosis is one cause of Achilles tendon ruptures. Usually, the history and physical examination are enough to determine whether the patient has a complete rupture versus a partial rupture. However, in cases of paratenonitis and associated tendinosis, an MRI of the Achilles tendon can be useful to differentiate between simple inflammation and intratendinous degeneration or partial tear. Ultrasound has also been useful to evaluate the Achilles tendon because it allows dynamic evaluation of the tendon function.