By Amy Bertrand, St. Louis Post-Dispatch, June 26, 2006

Q: What is bursitis, why does it hurt so much, and what can be done to prevent it? - M.G., Creve Coeur

A: Bursitis is an inflammatory condition of the bursae, which are small, fluid-filled sacs that lubricate and cushion pressure points between your bones and the tendons and muscles near your joints, says Dr. Charles Goldfarb, an orthopedic surgeon specializing in the hand and upper extremities at Barnes-Jewish Hospital and Washington University.

There are four major areas where Goldfarb says he sees bursitis:

• In the elbow, where you''ll see swelling at the back of the elbow.
• On the outside of the hip.
• On the front of the knee.
• In the shoulder at the shoulder joint.

One of the most common ways to get bursitis is from overuse. For instance, if you work at a job where you are on your knees a lot, bursitis can appear in your knee.

Those small bursa sacs can fill up with so much fluid it looks like you have an orange on your elbow, says Goldfarb, and that can certainly be painful. "It hurts because it''s an inflammatory problem," says Goldfarb. "It''s a pain response."

The best way to treat bursitis is to try to calm down the inflammation. Start by not using that area. If you have knee bursitis, stay off your knees. If you just can''t do that, try knee pads. Next, take an anti-inflammatory drug such as Motrin or Naproxen. You can also use a wrap bandage to help put pressure on the spot and decrease the size of the bursa.

Goldfarb says these methods work in most cases, but some people have to have the bursa drained or have a steroid injected.

When nothing else works, removing the bursa surgically is the last step.

The best way to prevent bursitis is to avoid any repetitive stress that may cause it. If you cannot do so, be sure to take frequent breaks or use cushioned pads. Also, strengthening and stretching your muscles can''t hurt.