The Achilles tendon is a tendon that attaches your calf muscle to your heel bone (calcaneus) and is the largest and strongest tendon in the human body – taking more force than any other joint, muscle, or tendon. The Achilles tendon allows you to move forwards from standing and comes into play whenever you’re accelerating, changing direction, or coming to a halt.
The result can be a rupture, usually at the point where the tendon attaches to the calcaneus. This can be a partial tear, where some of the fibers of the tendon get torn, or a complete tear, where the entire tendon comes away from the heel bone. In some cases, this also causes an ‘avulsion fracture’ where pieces of calcaneus bone break away along with the tendon.
Insertional Achilles tendonitis is inflammation of the tendon fibers of the back of the heel, where the Achilles tendon inserts into the heel bone. Insertional Achilles tendonitis is associated with decreased range of motion at the ankle. Furthermore, most patients begin to develop insertional Achilles tendonitis between the ages of 40-60 years old.
This condition typically develops gradually and isn’t linked to a single incident or trauma. In addition, there is another type of Achilles tendonitis known as non-insertional Achilles tendonitis. In cases of this condition, the fibers in the middle of the tendon begin to break down, swell and thicken. This type of Achilles tendonitis affects people who are younger and more active.