This is an illustration of the inside of the knee from a side view as if it was cut through the middle. You can see that there are several bursae around the knee. The pre-patellar bursa is just in front of the kneecap.Function of the pre-patellar bursa
As the knee bends and straightens with ordinary activities, the bursae - being lubricated - allow the tissues to slide and accommodate the activity. When a bursa becomes inflamed, perhaps from impact or involvement in repeated movement, it may fill with fluid and become painful, and range of motion of the knee may be reduced.