Disorders of the sacroiliac joint.

Controversies have surrounded the sacroiliac joint. The sacroiliac joint (SIJ) is a considerably complex and strong joint with limited mobility, mechanically serving as a force transducer and a shock absorber. Anatomical changes are seen in the SIJ throughout an individual's lifetime. The ligamentous system associated with the SIJ serves to enhance stability and offer proprioceptive feedback in context with the rich plexus of articular receptors. Stability in the SIJ is related to form and force closure. Movement in the SIJ is 3-D about an axis outside of the joint. The functional examination of the SIJ is related to a clinical triad.