The Sacroiliac Joint (SIJ) is structured by articular surfaces between the sacral and the iliac bones. The SIJ embraces different functions because it connects the spine with the pelvis, allowing the soaking up of vertical forces to form the spine, thus transferring vertical forces to the pelvis and lower extremities. The first goal of the SIJ is to preserve stability that is partly done by the muscles surrounding the SIJ and realized by various procedures, encompassing a large complex of ligaments connected to the SIJ. The range of motion of the SIJ is estimated to be around 2 to 4 degrees. The 35 muscles attached to the sacrum bone or innominate work together in synergy with the fascia and ligaments to move and ensure the trunk and lower extremities’ stability.
The SIJ is an essential source of pelvic and low back pain (LBP), which should consider the differential diagnosis of pelvic and LBP. The prevalence of SIJ pain is underappreciated because no research has been done concerning the SIJ posterior ligaments. An increased prevalence of LBP and its associated costs in the United States and the rest of the world. In Europe, the augmentation of LBP cases in an adult population is due to sedentary activities such as working with a computer.
Marcucci, Alexander, and Matthew found in a pilot study composed of a sample of 20 patients randomized after applying two different osteopathic release techniques on the posterior SIJ ligaments. A reduction of the pain in 18 patients, from which 12 patients had no pain anymore, and 6 patients had only reduced pain intensity. Only in cases, the applied techniques did not produce any effect. There is a need to investigate the potential function of SIJ posterior ligaments in LBP.