The sacroiliac joint: a review of anatomy and biomechanics with clinical implications

Objective: To examine the biomedical literature pertaining to the anatomy and biomechanics of the sacroiliac (SI) joint to update current concepts and treatment of SI joint dysfunctions. Data collection: The biomedical literature was reviewed for articles containing information on the anatomy, mechanics, dysfunction and treatment of the SI articulation. Emphasis was placed on information published in the past decade. Textbooks and prior reviews were used to compare past and present information. Results: The anatomy and mechanics of the SI joint and surrounding tissues are much more complex than taught in chiropractic colleges and technique systems. The motion of the joint is complex, involving simultaneous rotations of 3 degrees or less and translations of 2 mm or less in three dimensions. The axes of motion for the SI joint are not straightforward and are largely dependent upon the surface topography of the joints. Traditional chiropractic types of dysfunctions and displacements are oversimplified and specific SI joint adjustments have not been demonstrated to correct these displacements. The primary function of the integrated SI system is the transmission and dissipation of mechanical forces. History, physical examination and clinical diagnostic tests have failed to demonstrate predictive validity for true SI dysfunction. Conclusion: Treatment of the SI articulation is difficult and all known SI joint tests have questionable validity, with the exception of pain provocation tests. Clinical treatment should be aimed at improving the stability of the surrounding soft tissues and at reducing mechanical stresses and strains from poor posture or using orthotics to level the sacral base. Much more research is needed in the treatment of this area.