The Sacroiliac joint is a large joint of the body formed by the connection of the sacrum and the right and left iliac (pelvic) bones. The sacroiliac joints allow a small amount of movement and transmits all the forces of the upper body to the lower body, serving as a shock-absorbing structure. Sacroiliac joint dysfunction or sacroiliac joint pain can be a cause of lower back pain. The pain is usually localized to the lower aspect of the back or into the gluteal region and occasionally patients can experience pain into the lower limbs, mimicking sciatic pain. In some patients getting up from a sitting position or twisting, such as in bed, can trigger their low back pain. It is thought that approximately 15% of lower back pain is due to sacroiliac joint dysfunction.