If the condition has been present for some time, there may be a small lumps that can be felt underneath the skin over the patella. Sometimes these lumps give the feeling that something is floating around in front of the patella, and they can be very tender. These lumps are usually the thickened folds of bursa tissue that have formed in response to the chronic inflammation. The bursa sack may swell and fill with fluid at times. This usually related to your activity level.
More activity usually causes more swelling.
In people who are on their knees a lot, like carpet layers, the bursa can get to be very thick, a lot like a kneepad in front of the knee. Finally, if the bursa becomes infected , the front of the knee becomes swollen, very tender and warm to the touch around the bursa. You may run a fever and begin to chill. An abscess may form on the front of the knee and drain pus if the infection is not treated fairly quickly. The diagnosis of pre-patellar bursitis is usually obvious from the physical examination.