Retrocalcaneal bursitis is swelling (inflammation) of the fluid-filled sac (bursa) at the back of the heel bone (calcaneus).

A bursa acts as a cushion and lubricant between tendons and muscles sliding over bone. There are bursas around most large joints in the body, including the ankle.

The retrocalcaneal bursa is located in the back of the ankle by the heel. It is where the large Achilles tendon connects the calf muscles to the heel bone.

Repeated or too much use of the ankle can cause this bursa to become irritated and inflamed. Possible causes are excessive walking, running, or jumping.

This condition is commonly associated with Achilles tendinitis. Sometimes retrocalcaneal bursitis may be mistaken for Achilles tendinitis.

Those at risk for this condition include people just starting aggressive exercise regimens or who suddenly increase their activity without proper conditioning.