Knee bursitis is an injury of overuse. This occurs when your knee joint incurs repetition stress on the body’s joint, which leads to a painful inflammation. A bursa is small, fluid-filled sac that provides cushion and lubrication around the tendons and as such, prevents friction between the tendon and the bone. They provide comfort and help your joints move with ease. However, the constant rubbing of the tendon over the bone especially in areas that experience a lot of stress such as arms, shoulders, knees, ankles and hips.