A bursal sac is filled with fluid that provides a cushion between muscles/tendons and bones to decrease friction and irritation. There are bursal sacs around most of the body's joints. When a bursal sac gets infected or inflamed, it can lead to a painful condition called "bursitis." Although often caused by repetitive movement or overuse of a joint during sports or intense physical activity, bursitis can also result from injury, or arthritis of a joint.
The most common symptoms of bursitis are pain, stiffness, swelling and tenderness, usually in the joints of the elbow, shoulder, hip, knee or ankle. The heel and Achilles tendon can also be affected. Pain, which can develop gradually or be sudden and severe, may be accompanied by decreased mobility of the joint.
If conservative treatment methods are unsuccessful in treating the pain and discomfort caused by bursitis, bursal sac injections can be an effective way of reducing inflammation and diminishing pain. Anti-inflammatory steroid medication is injected directly into the bursal sac; as inflammation decreases, pain and discomfort subside, often for a few weeks or months. In some cases, one injection may be sufficient to alleviate symptoms.