The SI joint is the Sacroiliac Joint. It is where the Iliac Bone and the Sacral Bone connect with a very strong fibrous ligament. The movement is normally very limited due to the strength of the ligament. Injury to the joint can cause it to “open” or separate more than normal.
Some symptoms are pain in the local area of the joint. Sometimes, you may find it difficult to stay sitting correctly and find yourself leaning your body weight more on one side than the other. In severe cases, it is very difficult and painful to walk.