The sacroiliac joint (SIJ) is the largest axial joint in the body and is characterized as a large, diarthrodial synovial joint, which differs from others in that it has fibrocartilage in addition to hyaline cartilage. The SIJ is composed of well- developed ligaments and irregular articular surfaces to help limit motion and add stability as well as to serve as a site for muscle attachment. The SIJ has a complicated and ambiguous innervation. The SIJ can be a significant source of low back pain with a prevalence varying from 15–30% in patients with low back pain. In patients with persistent low back pain, magnetic resonance imaging (MRI) studies have found that SIJ disease is presented in approximately 20% of patients.