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Prepatellar bursitis is often caused by pressure from constant kneeling. Plumbers, roofers, carpet layers, coal miners, and gardeners are at greater risk for developing the condition.

A direct blow to the front of knee can also cause prepatellar bursitis. Athletes who participate in sports in which direct blows or falls on the knee are common, such as football, wrestling, or basketball, are at greater risk for the condition.

Other people who are more susceptible to the condition include those with rheumatoid arthritis or gout.

Prepatellar bursitis can also be caused by a bacterial infection. If a knee injury — such as an insect bite, scrape, or puncture wound — breaks the skin, bacteria may get inside the bursa sac and cause an infection. This is called infectious bursitis. Infectious bursitis is less common, but more serious and must be treated more urgently, though not always with surgery.

Photos show a patient with an inflamed bursa filled with fluid in the front of her left kneecap. Her right knee is normal.

• Pain with activity, but not usually at night
• Rapid swelling on the front of the kneecap
• Tenderness and warmth to the touch
• Bursitis caused by infection may produce fluid and redness, as well as fever and chills

Nonsurgical treatment is usually effective as long as the bursa is simply inflamed and not infected:

• Activity modification. Avoid the activities that worsen symptoms. Substitute another activity until the bursitis clears up. Low-impact exercise, such as cycling or using the elliptical machine, is a good option.
• Ice. Apply ice at regular intervals 3 or 4 times a day for 20 minutes at a time. Each session should reduce swelling considerably if the knee is also being rested.
• Elevation. Elevate the affected leg except when it is necessary to walk.
• Nonsteroidal anti-inflammatory drugs (NSAIDs). Medications such as naproxen and ibuprofen may relieve pain and control inflammation. Acetaminophen can be used as an alternative if you cannot tolerate NSAIDs or are allergic.

If the swelling and pain do not respond to these measures, your doctor may drain (aspirate) the bursa with a needle, then inject the bursa with a corticosteroid (cortisone injection). The corticosteroid is an anti-inflammatory drug that is stronger than medications that can be taken by mouth.

Infectious bursitis is initially treated with antibiotics. Surgical drainage is required if the infection does not respond to antibiotics alone.

Draining the bursa may also treat chronic swelling that causes disability, but if the swelling continues, your orthopaedic surgeon may recommend surgical removal of the bursa. After surgery, the knee should regain its flexibility in a few days,  and you can resume normal activities in a few weeks.

You can help prevent bursitis by following these simple recommendations:

• Wear kneepads if you work on your knees or participate in contact sports such as football, basketball, or wrestling.
• Rest your knees regularly by stopping to stretch your legs. You may also consider switching activities on a regular basis to avoid prolonged stress on your knees.
• Apply ice and elevate your knees after a workout.