What is bursitis? Bursitis is the inflammation of a fluid-filled sac around a joint. The bursa helps tendons slide smoothly over and around bones, and when it is inflamed (bursitis), you may experience pain, swelling and stiffness in the affected joint. Bursitis most commonly occurs in the knees, elbows, shoulders, and hips. Bursitis can develop acutely or can be a chronic condition that comes and goes over a long period of time. Bursitis can be caused by trauma to a joint, the overuse of a joint, or medical conditions such as arthritis or gout. Bursitis is most common in middle-aged individuals. Bursitis can affect anyone, but people who use a specific joint a great deal, such as the way a tennis player uses his or her elbow, and older people who have arthritis or gout are at the most risk. Bursitis is not a life-threatening condition, but it can severely impair mobility in the affected joint. Seek prompt medical care if you are being treated for bursitis but joint symptoms recur or are persistent.