The sacroiliac joint (SI joint) is located in the pelvis; it links the iliac bones (pelvis) to the sacrum (lowest part of the spine above the tailbone). It is an essential component for energy transfer between the legs and the torso.
Like any other joint in the body, the SI joint can be injured and/or undergo degeneration. When this happens, people can feel pain in their buttocks and sometimes in the lower back, hips, and legs. This is especially true while lifting, running, walking or even lying on the involved side.
It’s common for pain from the SI joint to feel like disc or lower back pain, or sometimes hip or groin pain. For this reason, SI joint disorders should always be considered the lower back, hip, and pelvic pain diagnoses.