Movement of the sacroiliac joint: Anatomy, systematic review, and biomechanical considerations

Several researchers investigated the anatomy and biomechanics of the sacroiliac joint (SIJ) to understand the relationship between lower back pain and the SIJ. Many studies concluded that the SIJ has little movement; however, some studies using spinopelvic parameters mentioned high change in pelvic incidence (PI). In this study, SIJ movement and PI change reported in previous studies were reviewed according to position and posture changes. Literature on SIJ movement was reviewed by searching through the publication databases. In biomechanical studies, the result of the rotational angle in the sagittal plane was mainly investigated to compare with the results of PI change. From the results of SIJ movement studies, the minimum movement of nutation and count-nutation was 0.01°, and maximum movement was 2.27°. From the results of PI change studies with different positions and movements, the highest change was 9°, and the lowest change was 0°. Movement of the SIJ was limited by its anatomical structure; maximum movement of the SIJ was 9° in a previous study. Therefore, SIJ movement should be studied more intensely as biomechanical perspective to understand its movement.