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 during activities like walking and running. The sacroiliac joint is designed to be stable, allowing for limited movement. It is supported by strong ligaments and is essential for maintaining balance and posture. Dysfunction or inflammation in this joint can lead to pain in the lower back and hips, often referred to as sacroiliac joint dysfunction.