If you’ve ever felt a deep, nagging ache in your lower back, hip, or even down into your leg, your sacroiliac joint (SIJ) may be the source. SIJ pain is incredibly common yet often overlooked — and getting the right assessment can make all the difference. What Is the Sacroiliac Joint? Your sacroiliac joint sits at the base of your spine, connecting your sacrum to your pelvis. It helps to transfer load between your upper body and legs. When these joints become irritated, stiff