Sudden or long-term trauma leads to inflammation of the bursae that causes a painful, often swollen knee. A common type is prepatellar bursitis, which happens in people who work on their knees.

Kneecap bursitis happens when your knee’s bursa sac is repeatedly irritated, damaged, or infected. The lining of the bursa thickens, producing extra fluid, which causes the bursa to swell.

this could mean that the bursa — a fluid-filled sac in the knee that helps lubricate the joint — might be inflamed. If you think you have bursitis, it’s best to limit your activity until the ...

What causes it: Knee bursitis occurs when one of the bursae in your knee becomes inflamed because of repeated strain, Wilder says. This is usually because a runner decides to increase their ...

Shoulder bursitis is inflammation of a bursa, a fluid-filled sac, in the shoulder joint. The bursa provides padding between ...