Services Bursitis Bursitis The tiny, fluid-filled sacs called bursae (bur-SEE), which cushion the bones, tendons, and muscles next to your joints, can become inflamed and cause bursitis (bur-SY-tis). When bursae become inflamed, bursitis develops.Bursitis most frequently occurs in the hip, elbow, and shoulder. https://gainterventionalpain.com/bursitis/