Here is a really important concept about the SI joint: How is an SI joint supposed to stay in place? The body has 2 main systems to maintain stability in the SI joint: Form closure and force closure. 1) Form closure has to do with the shape of the bones that make up the SI joint (the two hip bones and the sacrum). According to Physiopedia, “The sacrum and the … Continue reading SI Joint Concepts: Form Closure vs. Force Closure