A bursa is a fluid-filled sac that functions as a gliding surface to reduce friction in your joints. Each knee joint contains 11 bursae. Bursitis occurs when a bursa produces too much fluid due to irritation and becomes inflamed.
Knee bursitis is common among athletes because one of the main causes is a direct hit to the knee. Knee bursitis can also be caused by repeated kneeling (like in jobs such as roofing), arthritis, and gout. Common signs and symptoms include pain and swelling, reduced mobility, and inflammation. Your knee may also be warm and tender to the touch.
Rest, cold, compression, and anti-inflammatory medications are the main treatment methods. Cortisone shots are used in more severe cases of bursitis, but they should not be your first choice for treatment. In cases of more persistent bursitis, the fluid can be drained from the bursa in order for the swelling to go down, but this does not guarantee that the bursitis will go away.