Greater trochanteric pain syndrome (GTPS), also known as trochanteric bursitis, is inflammation of the trochanteric bursa, a part of the hip. This bursa is at the top, outer side of the femur, between the insertion of the gluteus medius and gluteus minimus muscles into the greater trochanter of the femur and the femoral shaft. It has the function, in common with other bursae, of working as a shock absorber and as a lubricant for the movement of the muscles adjacent to it. Occasionally, this bursa can become inflamed and clinically painful and tender. This condition can be a manifestation of an injury (often resulting from a twisting motion or from overuse), but sometimes arises for no obviously definable cause. The symptoms are pain in the hip region on walking, and tenderness over the upper part of the femur, which may result in the inability to lie in comfort on the affected side.