Knee Bursitis

Prepatellar bursitis is inflammation of a small fluid-filled cushion that sits between the skin and the front of the kneecap. When that cushion becomes irritated and fills with extra fluid, it produces a visible, squishy swelling over the kneecap, and putting the knee on the ground becomes painful. It is common among people who kneel regularly at work. There are two forms: a non-septic form from repeated irritation, a blow, or gout, and a septic form in which bacteria infect the bursa. They are treated very differently, so telling them apart guides care.

Common symptoms include:

• A soft, squishy swelling directly over the front of the kneecap
• Pain with kneeling or pressing on the front of the knee
• Normal bending and straightening, since the bursa sits outside the joint
• Warmth and redness over the kneecap, especially with gout or infection
• Fever or spreading redness when the bursa is infected

The diagnosis is usually apparent from a soft, compressible lump sitting on the front of the kneecap, with the knee still bending normally. The most important step is aspiration, in which a small amount of fluid is drawn from the bursa and tested to show whether it is infected, gout-related, or simply inflammatory. That result drives the treatment decisions. An MRI is not routinely needed.

Treatment depends on whether the bursa is infected. Non-septic bursitis is managed with:

• Activity changes and padding, staying off the knees as much as possible
• Over-the-counter anti-inflammatory medication for a flare
• Aspiration to relieve swelling and confirm the diagnosis
• A corticosteroid injection after draining, when the fluid keeps returning

Septic bursitis is treated with aspiration, culture, and antibiotics, with repeat drainage as needed. Surgery is reserved for a septic bursa that does not clear or a chronic bursa that keeps refilling, removing the bursa entirely.

For a fuller explanation, including anatomy, diagnosis, and the full range of treatment:

• Prepatellar (Kneecap) Bursitis — AAOS OrthoInfo