Bursae are small, fluid-filled sacs that provide cushioning and lubrication between bones, tendons, and muscles near your joints. When a bursa becomes inflamed, this is called bursitis. It inhibits movement and causes pain in the afflicted area. Bursitis often affects the joints in your shoulders, elbows, or hips. But you can also have bursitis in your knee, heel, and the bottom of your big toe. Overuse, stress, and direct trauma to a joint are common causes of bursitis. It can also be a result of an infection, gout, or arthritis. Bursitis of the hip, or trochanteric bursitis, is frequently associated with a hip injury or arthritis. Pressure from standing or sitting for a long time is also a contributing factor.