A bursa is a fluid-filled sac that cushions areas of friction between tendon and bone. These sacs reduce friction between moving parts of the body, such as in the hip, knee, and heel. A constant rubbing of the tendon over the bone with high amounts of repetitive motion can cause inflammation and irritation, known as bursitis. Symptoms of bursitis vary from an achy pain and stiffness of the joint to a burning sensation of the joint around the inflamed bursa. With this condition, the pain is usually worse during and after activity, and the bursa and surrounding joint area can become stiffer the following day.
The retrocalcaneal bursa is located in the feet between the Achilles tendon and the heel bone. When it becomes inflamed, it is known as Achilles tendon bursitis and causes heel pain. Because it occurs in the same area, Achilles tendon bursitis may be mistaken for Achilles tendinitis. It is possible to have both Achilles tendinitis and Achilles tendon bursitis at the same time, which is known as Haglund’s syndrome.