The sacroiliac joints (SI) are the foundation of the spine and are located at the junctions of the sacrum and ilium on each side. These complex joints, composed of systems of ligaments and multiplanar joint surfaces, transmit the forces exerted through the spine from the upper body to the legs. The SI joint is designed to absorb shock forces and is naturally constrained to only limited movement. Instability in the SI joint is a major pain generator in some patients. Although there have been many advances in surgical techniques to address instability problems in the lumbar spine, instability in the SI joint has remained relatively unaddressed, with most patients running out of options once conservative treatments have failed to offer continued relief from painful SI symptoms.