Insertional Achilles tendinitis involves the lower portion of the heel, where the tendon attaches (inserts) to the heel bone.
In both noninsertional and insertional Achilles tendinitis, damaged tendon fibers may also calcify (harden). Bone spurs (extra bone growth) often form with insertional Achilles tendinitis.
Tendinitis that affects the insertion of the tendon can occur at any time, even in patients who are not active.