Patient question
My kneecap is swollen and red. Is it infected?
Dr. Pablo GelberOrthopaedic Knee Surgeon
Quick answer
It may be. A swelling over the kneecap that becomes red, hot, increasingly painful, or comes with fever is a warning sign of infected bursitis and should be seen the same day. It usually needs antibiotics and sometimes drainage, advises Dr. Pablo Gelber, knee surgeon at Aman Hospital in Doha, Qatar.
How infection gets in
The bursa over the kneecap sits just under the skin. A small cut, graze, insect bite or crack in dry skin can let bacteria in, sometimes without the person remembering any injury. Manual workers, people who kneel a lot, and people with diabetes or reduced immunity are at higher risk.
Infection in the bursa is different from infection inside the knee joint. Both are serious, but a joint infection usually makes the whole knee swollen and very painful to move, which is a surgical emergency.
Signs that point to infection
- Redness spreading over and around the kneecap
- Heat when you touch the swelling compared with the other knee
- Pain that is increasing rather than settling
- Fever, chills or feeling generally unwell
- A wound, graze or pus over the swelling
- Red streaks spreading up or down the leg
What treatment involves
The doctor examines the swelling and the knee joint and may draw fluid from the bursa with a needle to test it. Blood tests help gauge infection. Treatment usually starts with antibiotics, by mouth for milder cases or through a drip if the infection is more severe. The bursa may need draining, sometimes more than once.
Surgery to wash out or remove the bursa is considered when infection does not respond. Do not try to drain the swelling yourself and do not apply heat.
When it is probably not infected
A soft, painless or mildly tender swelling without redness, heat or fever is much more likely to be simple pressure bursitis. It usually settles with padding, less kneeling and ice. Even so, keep watching it, and seek care if any of the warning signs appear. Book an assessment if it has not improved in two to three weeks. At Aman Hospital in Doha, Dr. Gelber assesses both kinds and arranges ultrasound or fluid testing where needed.
Frequently asked questions
Can infected bursitis spread into the knee joint?
It is uncommon, but serious infection can spread if untreated. That is why early treatment matters, and why a knee that becomes painful to move needs urgent review.
How long does infected bursitis take to heal?
With prompt treatment, many patients improve within days of starting antibiotics, and the swelling settles over the following weeks. The course depends on severity and examination.
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