Tiger Woods CBD Gummies Sacroiliac pain is a 'hidden' pain within the appreciate that most medical doctors don't have any idea that such intense pain can be due to this joint. The sacroiliac (or S-I joint) is where the sacrum (a triangular shaped bone located under your lumbar spine) and the ilium connect collectively. This S-I joint area, in conjunction with the ankle are the two exposed areas of the frame that get a terrible muscular deliver to stabilize the bones.