Bursitis is the inflammation of a bursa, which is a small, fluid-filled sac that acts as a cushion and reduces friction between bones, tendons, and muscles around a joint. Bursae are located in various parts of the body, including the shoulders, elbows, hips, and knees. When a bursa becomes irritated or inflamed, it can cause pain, swelling, and restricted movement in the affected area. read more