A bursa is a small fluid-filled sac that reduces friction where tissues glide over one another. The knee has several, and when one becomes inflamed the result is localized pain and sometimes visible swelling.
The useful question isn't whether you have bursitis — it's which bursa, because each has a different cause and a different fix.
The main ones
Prepatellar bursitis
Front of the kneecap. Classically caused by prolonged kneeling, which is why it's long been called housemaid's knee. Produces a squishy, sometimes dramatic swelling directly over the patella. More detail: prepatellar bursitis.
Pes anserine bursitis
Inner knee, roughly two to three finger-widths below the joint line. Common in runners, in people with knee osteoarthritis, and where hip control is poor. Often mistaken for a medial meniscus problem. More detail: pes anserine bursitis.
Infrapatellar bursitis
Below the kneecap, around the patellar tendon. Associated with jumping sports and repetitive kneeling.
Suprapatellar bursitis
Above the kneecap. Usually secondary to something else in the joint rather than a standalone problem.
How it differs from a joint problem
Bursitis pain is typically superficial, well-localized and tender to direct touch. Intra-articular problems tend to produce deeper, more diffuse pain, often with mechanical symptoms such as locking or giving way. Swelling from bursitis sits on top of the structure; joint swelling fills the joint itself.
Treatment
- Remove the aggravating load — kneeling pads, activity modification, training volume adjustment
- Settle the inflammation — relative rest early, with Class IV laser a useful adjunct
- Address the cause — hip and quadriceps strength, and frontal-plane control for the running-related presentations
- Soft tissue therapy for the surrounding musculature, particularly in pes anserine cases
- Graded return to full loading
Most knee bursitis settles well with the right combination of load management and strengthening. Persistent or recurrent cases usually mean the underlying cause hasn't been addressed.