Achilles Paratenonitis

What is Achilles Paratenonitis?

The Achilles tendon sits at the back of the ankle connecting the calf muscle to the heel bone. The Achilles Tendon does not have a true synovial sheath; instead, it has a paratenon composed of flexible connective tissue that allows for tendon gliding with activity.

The function of the Achilles Paratenon is to protect the Achilles Tendon from surrounding structures and to reduce friction. The Paratenon has a very good blood supply, and when irritated, it can become painful and inflamed, leading to Achilles Paratenonitis. The paratenon is innervated by nerves from local cutaneous nerves—in particular, the sural nerve.

In this article, we will explore the causes, symptoms, diagnosis, and treatment for Paratenonitis. It is sometimes referred to as Achilles Tenosynovitis.

Achilles Paratenonitis Causes

Achilles Paratenonitis is often the result of an acute overload of the Achilles tendon or friction from a bony protuberance such as Haglund’s deformity. An overload results from a sudden increase in running or impact activities. Other causes can be poorly fitted footwear that causes friction of the paratenon.

Symptoms of Achilles Paratenonitis

Sharp constant pain along the entire Achilles Tendon is associated with Achilles Paratenonitis.

There can be audible crepitus when moving to flex the foot while it is common for swelling along the Achilles Tendon. The space between the tendon and the sheath fills with fluid to give it a swollen sausage-like appearance.