Sacroiliac joint dysfunction is improper movement of the joints at the bottom of the spine that connect the sacrum to the pelvis. It can result in pain in the low back and legs, or inflammation of the joints known as sacroiliitis.acroiliac joint dysfunction refers to pain in these joints when they move either too much or too little. Hypermobility, or too much movement in the sacroiliac joints, is a result of loose ligaments supporting the joints. Hypermobility has many causes, including pregnancy or injury to ligaments.