Achilles Tendinitis

Part 1

Achilles tendinitis is a common condition that occurs when the large tendon that runs down the back of the lower leg becomes irritated and inflamed. 

The Achilles tendon is the largest tendon in the body. It connects the calf muscles to the heel bone and is used when you walk, run, climb stairs, jump, and stand on your tip toes. 

Although the Achilles tendon can withstand great stresses from running and jumping, it is also prone to tendinitis, a condition associated with overuse.


Description

Achilles tendinitis pain can occur within the tendon itself or at the point where it attaches to the heel bone, called the Achilles tendon insertion.

Simply defined, tendinitis (also spelled “tendonitis”) is acute inflammation of a tendon. Inflammation is the body’s natural response to injury and often causes swelling, pain, or irritation.

You may also come across the term “tendinopathy,” which is used to describe a condition in which the tendon develops microscopic degeneration as a result of chronic damage over time. Tendinitis, tendinosis, and tendinopathy are all common terms which essentially refer to the same problem.

Achilles tendinitis is different than an Achilles rupture, a condition where the tendon becomes separated off the heel bone or completely torn in half. 

Achilles tendon rupture typically results from a sudden injury. This article will focus on Achilles tendinitis rather than Achilles tendon rupture.

There are two types of Achilles tendinitis, based on which part of the tendon is inflamed. The two types can occur separately or at the same time.

  1. Noninsertional Achilles Tendinitis – In noninsertional Achilles tendinitis, fibers in the middle portion of the tendon (above where it attaches to the heel) are affected. Over time, the fibers may begin to break down and develop tiny tears. This can lead to tendon swelling and thickening. Noninsertional tendinitis more commonly affects younger, active people, especially runners.
  2. Insertional Achilles Tendinitis – Insertional Achilles tendinitis involves the lower portion of the tendon, where it attaches (inserts) to the heel bone (also known as the calcaneus).

In both noninsertional and insertional Achilles tendinitis, damaged tendon fibers may calcify (harden) over time. Bone spurs often form on the heel with insertional Achilles tendinitis.

Insertional Achilles tendinitis can occur at any time or activity level, although it is still most common in runners. It is frequently caused by calf muscle tightness, which places increased stress on the Achilles tendon insertion.