The sacroiliac joint is a connection between the sacrum, the triangular bone at the base of the spine, and the iliac bones of the pelvis. This joint plays a crucial role in transferring weight and forces between the upper body and the lower limbs, providing stability during movement. The sacroiliac joint is a strong, yet flexible joint that allows for limited movement, which helps absorb shock during activities like walking and running. Dysfunction or inflammation in this joint can lead to pain in the lower back and hips, often referred to as sacroiliac joint dysfunction.