Prepatellar Bursitis

Overview

A bursa is a small, fluid-filled sac that cushions and reduces friction between skin, tendons, and bone. The prepatellar bursa sits just in front of the kneecap (patella), between the skin and the bone. Prepatellar bursitis is inflammation of this sac, which causes it to fill with extra fluid and swell.

It is often called "housemaid's knee" because frequent kneeling is a common cause. Most cases are not serious and settle with simple measures, but the bursa can become infected, which needs prompt treatment.

Symptoms

Prepatellar bursitis usually causes a soft, swollen lump directly over the kneecap. Other features include:

• Swelling at the front of the knee that may come on gradually or suddenly
• Tenderness and pain, especially when kneeling or pressing on the area
• Limited knee bending because of the swelling
• Warmth and redness over the bursa

Marked redness, significant warmth, increasing pain, fever, or feeling generally unwell suggest the bursa may be infected (septic bursitis) and require urgent medical attention.

Causes

The prepatellar bursa can become inflamed from:

• Repeated kneeling: Common in jobs and hobbies that involve a lot of time on the knees, such as flooring, plumbing, gardening, and cleaning.
• A direct blow or fall onto the front of the knee.
• Infection: Bacteria entering through a cut, scrape, or graze over the kneecap can cause septic bursitis.
• Underlying conditions: Gout and rheumatoid arthritis can inflame the bursa.

Risk Factors

• Occupations or hobbies involving prolonged kneeling
• Sports with frequent falls onto the knees
• Breaks or scrapes in the skin over the kneecap
• Gout or rheumatoid arthritis
• A weakened immune system, which raises infection risk

Diagnosis

Diagnosis is usually based on the appearance and history of the knee. A doctor examines the swelling and asks about kneeling, injury, or signs of infection. Further tests may include:

• Aspiration: Drawing fluid from the bursa with a needle to relieve pressure and, if infection is suspected, to test the fluid.
• Blood tests: To look for infection or conditions such as gout.
• Imaging: X-rays or ultrasound if a fracture, foreign body, or another problem is suspected.

Treatment

Treatment depends on whether the bursitis is from irritation or infection.

• Self-care for non-infected bursitis: Rest, avoiding kneeling, ice, elevation, and over-the-counter anti-inflammatory medicine usually reduce swelling over days to weeks.
• Aspiration: Draining the fluid can ease pressure and discomfort.
• Antibiotics: Needed promptly if the bursa is infected; the fluid may need draining as well.
• Other measures: Kneepads and activity changes help prevent recurrence; persistent or repeated cases may rarely need surgical removal of the bursa.

Prevention

• Wear protective kneepads for work or activities that involve kneeling
• Take breaks and change position to avoid prolonged pressure on the knees
• Clean and protect any cuts or scrapes over the kneecap to prevent infection
• Treat underlying conditions such as gout

When to See a Doctor

See a doctor if knee swelling does not improve with rest, keeps returning, or limits your movement. Seek prompt medical care if you have signs of infection, such as:

• Spreading redness and warmth over the knee
• Increasing pain
• Fever or chills
• An open wound or cut over the swollen area

Infected bursitis can spread and needs timely antibiotic treatment.

Related Topics

Frequently Asked Questions

References

1. American Academy of Orthopaedic Surgeons (OrthoInfo). Knee Bursitis.
2. Mayo Clinic. Bursitis — Symptoms and causes.
3. MedlinePlus, U.S. National Library of Medicine. Bursitis.
4. National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS). Bursitis.