Haglund’s deformity is a problem with the back of the heel or calcaneus bone in which there is an enlargement of the bone and also a bursa commonly develops over the bone to protect it. The combination of the enlarged bone and the bursa can become painful from pressure from footwear. This can be a particular problem where the footwear is very rigid like in ski boots or ice skates.
The continued pressure from the footwear can irritate the bursa to create a condition called retrocalcaneal bursitis – this can lead to quite an enlargement that can be seen at the back of the heel.
The cause of that enlarged bone is that it is just a normal anatomical variation; some people have larger bits of bone at the back of the heel and others do not. We did not evolve to wear shoes, so when you put a shoe on over that enlarged bone it gets irritated and the bursitis develops. This means that Haglund’s deformity is just a normal anatomical variation that has been irritated by wearing shoes.
The condition is best treated by removing the shoe pressure with the use of open heel shoes, padding to keep the shoe away from the painful area to allow the bursitis to settle. If the problem is ongoing, then surgery can be an option to remove the enlarged bit of bone.