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. It is different than non-insertional Achilles tendonitis, which causes pain in the lower calf, where the Achilles tendon and calf muscle meet.

People who are affected are often in their 40s, 50s, or 60s. Achilles tendonitis usually develops gradually and is not linked with a single incident or trauma.