Hip bursitis is a common problem that causes pain over the outside of the upper thigh. A bursa is a fluid filled sac that allows smooth motion between two uneven surfaces. For example, in the hip, a bursa rests between the bony prominence over the outside of the hip (the greater trochanter) and the firm tendon that passed over this bone. When the bursal sac becomes inflamed, each time the tendon has to move over the bone, pain results. Because patients with hip bursitis move this tendon with each step, hip bursitis symptoms can be quite painful.