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About.com Health's Disease and Condition content is reviewed by Kate Grossman, MD

Prepatellar bursitis, also known as housemaid's knee, is a common cause of swelling and pain on top of the kneecap. The name "housemaid's knee" comes from the association of this condition with individuals whose work necessitates kneeling for extended periods of time. Prepatellar bursitis is common in professions such as carpet layers and gardeners.

What is a bursa?
A bursa is a thin sack filled with the body's own natural lubricating fluid. This slippery sack allows different tissues such as muscle, tendon, and skin slide over bony surfaces without catching. These bursa are normally very thin (like a plastic bag with the air sucked out of it), but they do present a potential space that can become inflamed and irritated. This is what is known as bursitis.

If the inflammation of bursitis is associated with trauma and a break in the skin, the bursa can become infected, this is called infected bursitis

What are the symptoms of prepatellar bursitis?
The symptoms of prepatellar bursitis or knee bursitis include:

• Swelling over the kneecap
• Limited motion of the knee
• Painful movement of the knee

The swelling of knee bursitis is within the bursa, not the knee joint itself. People often call any swelling of the knee joint "water on the knee," but it is important to differentiate fluid accumulation within the bursa, versus fluid accumulation within the knee joint.

Symptoms of prepatellar bursitis are usually aggravated by kneeling, and relieve when sitting still.

What is the treatment of prepatellar bursitis (knee bursitis)?
Treatment of prepatellar bursitis begins with avoidance of the aggravating activity. In some individuals, drainage or excision of the bursa may be indicated. In cases of infection, it is important that antibiotics are also administered.

If a bursa is drained, this can be performed in the office using a needle and a syringe. This is especially helpful in cases of possible infection. The fluid can then be analyzed to detect possible infection. If the fluid continues to accumulate, excising, or removing the bursa, can be considered. This procedure is performed as an outpatient in the operating room.

The images in this article were generously provided by Medical Multimedia Group, Inc.