Overview
what it is and why it mattersThere is a small fluid-filled cushion (a bursa) sitting right between the skin and the front of your kneecap. When that cushion gets irritated and fills with fluid, the front of the knee balloons out into a soft, sometimes painful swelling. That is prepatellar bursitis. The classic triggers: hours of kneeling at work (giving it the nicknames plumber's knee and carpet layer's knee), a direct hit to the front of the knee, a gout flare, or an infection working its way in. If it is infected (septic bursitis), it needs antibiotics and sometimes urgent drainage, a different problem from the everyday irritation kind.
Symptoms
what you may notice- Soft swelling on the front of the kneecap: a visible, squishy lump right over the kneecap that may appear quickly after a bump or slowly from repeated kneeling.
- Pain with kneeling: putting your knee on the ground sends a sharp ache through the front of the knee.
- Warmth and redness: the skin over the kneecap feels hot and looks red, especially if infection or gout is the cause.
- Normal knee bending: because the bursa sits outside the joint, you can usually bend and straighten your knee without trouble.
- Fever or spreading redness (if infected): a septic bursa may come with fever, chills, and redness that spreads beyond the kneecap. This needs urgent care.
Diagnosis
exam first, imaging secondThe first clue is soft, visible swelling sitting right on top of the kneecap. Because the bursa is outside the joint itself, you can usually still bend and straighten your knee without trouble. To figure out which kind you have, your provider draws a small amount of fluid from the swelling with a needle (aspiration) and sends it to the lab: the cells, crystals, and culture results tell us whether it is an infection, a gout flare, or just inflammation. An MRI is reserved for cases where we want to rule out other front-of-knee problems.
How We Treat It
two tracks, depending on infectionThe first step is to find out whether the bursa is infected. Your provider draws a little fluid with a needle to check, then follows the matching track below. The everyday irritation kind and the infected kind are treated very differently.
If it is not infected
1
Activity modification & padding
Stay off your knees as much as possible, and wear thick knee pads when you cannot avoid kneeling. Most mild cases settle down with this alone.
2
Aspiration
Drawing the fluid out with a needle (aspiration) both shrinks the swelling on the spot and lets the lab tell us what is driving it.
3
NSAIDs
An over-the-counter anti-inflammatory like ibuprofen can take the edge off the flare while the underlying cause is being addressed.
4
Corticosteroid injection
If aspiration alone does not keep the bursa from refilling, a steroid shot into the bursa right after draining it cuts down the chance of it coming back.
If it is infected (septic bursitis)
1
Aspiration & culture
Fluid is drawn from the bursa and sent to the lab. A positive culture confirms infection and guides the antibiotic choice.
2
Antibiotics
IV antibiotics in the hospital if the infection is serious, or oral antibiotics if it is milder. Close follow-up to make sure the infection is clearing.
3
Surgical drainage
If antibiotics alone do not clear the infection, the bursa is drained surgically in the OR.
Surgical Options
if non-operative care isn't enoughSurgery (bursectomy: removing the bursa entirely) is reserved for two stubborn cases: an infected bursa that will not clear with antibiotics and drainage, or a chronic one that keeps refilling no matter how many times it is drained or injected.
Frequently Asked
questions we hear in clinicWhat is prepatellar bursitis?
There is a small fluid-filled cushion (a bursa) sitting right between the skin and the front of your kneecap. When that cushion gets irritated and fills with fluid, the front of the knee balloons out into a soft, sometimes painful swelling. That is prepatellar bursitis.
What causes it?
The classic triggers are hours of kneeling at work (giving it the nicknames plumber’s knee and carpet layer’s knee), a direct hit to the front of the knee, a gout flare, or an infection working its way in.
Can I still bend my knee?
Usually yes. Because the bursa sits outside the joint itself, you can typically bend and straighten your knee without trouble even when the front of the kneecap is swollen.
How is it diagnosed?
Your provider looks for soft, visible swelling sitting right on top of the kneecap. To figure out which kind you have, they draw a small amount of fluid from the swelling with a needle (aspiration) and send it to the lab. The cells, crystals, and culture results tell us whether it is an infection, a gout flare, or just inflammation. An MRI is reserved for cases where we want to rule out other front-of-knee problems.
How do I know if it is infected?
An infected (septic) bursa may come with fever, chills, warmth, and redness that spreads beyond the kneecap. This kind needs urgent care, antibiotics, and sometimes drainage, a different problem from the everyday irritation kind.
Will I need surgery?
Rarely. Surgery (bursectomy: removing the bursa entirely) is reserved for two stubborn cases: an infected bursa that will not clear with antibiotics and drainage, or a chronic one that keeps refilling no matter how many times it is drained or injected.
Providers Who Treat Prepatellar Bursitis
sports-medicine team
Further Reading
authoritative sourcesExternal patient-education references and related OSI pages for additional background: