Bursitis is the swelling of a bursa, a small jelly-like sac that acts as a cushion between the bone and the overlying soft tissues to reduce friction between them. The bony point of the hip (greater trochanter) has a large bursa that can become irritated.
There are 2 major bursae of the hip – the trochanteric bursa and the ischial bursa. The trochanteric bursa is located on the outside of the hip, while the ischial bursa is at the upper buttock area.