Bursae are fluid filled sacs that act to reduce friction between bones, tendons and/or muscles surrounding certain joints. The ischial bursa is located over the ischial tuberosity (sitting bone) and can become irritated, inflamed and painful (bursitis) by direct trauma or via hamstring strains. It typically presents as pain over the buttock possibly traveling down the back of the leg and may mimic sciatica.
This pain may be relieved by actions such as pressing down on a brake pedal when driving, which reduces pressure on the ischial bursa. It is generally accompanied by a history of prolonged sitting on hard surfaces, horse riding or sports that involve repetitive hamstring contraction such as speed walking.