<p>A bursa is a small, fluid-filled sac that acts as a cushion between a bone and other moving parts, such as muscles, tendons, or skin. Bursitis occurs when a bursa becomes inflamed. People get bursitis by overusing a joint. It can also be caused by an injury. It usually occurs at the knee or elbow. Kneeling or leaning your elbows on a hard surface for a long time can make bursitis start. Doing the same kinds of movements every day or putting stress on joints increases your risk.</p> <p>Symptoms of bursitis include pain and swelling. Your doctor will diagnose bursitis with a physical exam and tests such as x-rays and MRIs. He or she may also take fluid from the swollen area to be sure the problem isn't an infection.</p> <p>Treatment of bursitis includes rest, pain medicines, or ice. If there is no improvement, your doctor may inject a drug into the area around the swollen bursa. If the joint still does not improve after 6 to 12 months, you may need surgery to repair damage and relieve pressure on the bursa.</p> <p class="">NIH: National Institute of Arthritis and Musculoskeletal and Skin Diseases</p>