A Haglund's deformity is a bump in the back of the heel bone. The Achilles tendon runs over the bump. Patients with a Haglund's deformity may or may not have pain. Sometimes, the pain is caused by shoes rubbing against the bump. At other times it can be part of pain of degeneration in the Achilles tendon due to the pressure placed there. It is not always clear how much of this Achilles tendon problem is due to the Haglund's deformity.
If prominence is the main issue, then the goal of Haglund's deformity surgery simply is to make the heel bone less prominent. If the Achilles tendon has degenerated as well, then the procedure may involve the Achilles tendon directly.