By Aubrey Bailey, PT, DPT, CHT   Medically reviewed by Oluseun Olufade, MD Shoulder bursitis is inflammation of a bursa, a fluid-filled sac, in the shoulder joint. Bursae provide padding between bones, tendons, and ligaments to reduce friction and improve joint movement throughout the body. There are multiple bursae in the shoulder, but this condition most commonly affects one called the subacromial bursa. Click here to learn…