Bursitis is the painful inflammation of the bursa, a padlike sac that cushions the movement between the bones, tendons and muscles near the joints. Bursitis is most often caused by repetitive movement, and is also known by several common names including weaver's bottom, clergyman's knee, and miner's elbow.

There are over 150 bursae in the human body. Each sac contains a small amount of synovial fluid, a clear liquid that acts as a lubricant. Inflammation of the bursae causes pain on movement. The most common site for bursitis to occur is the shoulder (subdeltoid), but it also is seen in the elbows, hips, knees, heels, and toes.

The most common cause of bursitis is repeated physical activity, but it can flare up for no known reason. It can also be caused by trauma, rheumatoid arthritis, gout, and acute or chronic infection.

Pain and tenderness are common symptoms. If the...