A bursa is a small sack filled with fluid. These bursae (plural of "bursa") are located wherever tendons or ligaments move across joints, to protect the bones, tendons and muscles that surround joints. Protection by bursae comes from the ability of these sacks to cushion shock or to reduce the effects of friction during movement of a joint.

Repetitive trauma, pressure, or overuse can lead to inflammation of a bursa. Also, aging is another cause of bursal inflammation. Inflammation is the body's response to any type of injury. When a bursa becomes inflamed, it becomes swollen due to two factors. First, the lining of the bursa thickens; then this thickened lining starts to produce more fluid. A person who develops bursitis will experience the common symptoms of inflammation which include pain, swelling, heat and possibly redness.

There are more than 150 bursae located throughout the body. The most common sites for bursitis to develop are the hips, shoulders, knees, elbows, and feet. A discussion of the various types of bursitis is in another article.

The location of the various bursae makes a diagnosis difficult when a joint becomes painful. It could be bursitis, arthritis, tendonitis, or perhaps a mixture of all three!

The diagnosis is important because the treatment is different for the three conditions... and because the diagnosis has different implications. For example, if a patient develops a painful hip, a diagnosis of arthritis possibly requiring surgery is very different from the treatment that would be administered if the diagnosis were bursitis.

A skilled rheumatologist or orthopedist can provide meaningful and expert advice when it comes to figuring out what the problem is and what to do about it.

Prevention is possibly the most important thing a patient can do. Regular low impact exercise is valuable but a person should avoid too much exercise as it can lead to overuse. Overuse then leads to bursitis. Stretching exercises are also useful for helping to avoid bursitis. Once a person has had bursitis, they are prone to developing it again so it's important to cushion high risk areas. This involves the use of pads to protect joints or simply changing the way certain activities are done.

So what about treatment? The most important part of treatment is getting an accurate diagnosis. Most bursitis responds to simple measures such as rest, ice, and over-the-counter non-steroidal anti-inflammatory drugs (NSAIDs). Patients occasionally require a prescription-strength NSAID. Physical therapy is often useful. In cases where the bursitis fails to improve or gets worse, withdrawing fluid from the inflamed bursa and injecting steroid is warranted. Steroid injection should be administered using ultrasound guidance whenever possible.