User:DonTigny

The Myth of the Immobile Sacroiliac Joint

Following the publication of Smidt et al in 1995 (1) on the measurement of movement of the SIJ in the long straddle position (LSP) Sturesson asked me to review Smidt’s work regarding possible errors in measurement or procedure, because Smidt’s results had varied so much from Sturesson’s earlier work.(2) Sturesson used tiny implanted tantalum balls, measured pelvic movement in the LSP and reported finding about 2 degrees of movement at the SIJ while Smidt had reported about 30 degrees of motion.

I studied both articles and found no errors in measurement, but noted that Sturesson had blocked the pelvis in the frontal plane in the LSP for his measurements. In the LSP the pelvis moves oblique to the line of travel and into asymmetry in order to extend the length of the stride. Blocking the pelvis in the frontal plane left it in a position of symmetry and resulted in Sturesson measuring the symmetrical pelvis in the LSP with the right leg advanced and again with the left leg advanced. Thus Sturesson measured only a minimal movement in the blocked symmetrical pelvis. This was a fatal error in procedure that has been often quoted often when speaking of a supposedly essentially immobile sacroiliac joint.

I x-rayed the pelvis in asymmetry with counter rotation right and left to demonstrate lateral sacral flexion of the spine in the LSP (3). I also did one view in the LSP with the pelvis blocked in the frontal plane, as per Sturesson, and found that pelvic symmetry was obvious in spite of the LSP. These views are on my website with my bibliography at www.thelowback.com. How it works, why it hurts and how to fix it.

I have found that when the pelvis moves into asymmetry in the LSP the innominate on the side of loading moves the sacrum caudad on that side, but does not move caudad on the sacrum. (see x-rays) The ilial tuberosities prevent caudad movement of the innominate on the sacrum during normal function and with dysfunction. The innominate on the contra lateral side moves the sacrum cephalad, which causes the sacrum to flex laterally toward the side of loading creating an oblique axis. The sacrum then moves on that oblique axis to drive counter rotation of the trunk in order to to decrease loading forces to the femoral head.

I have found a commonly overlooked, reversible, biomechanical vulnerability of the sacroiliac joints in anterior rotation of the innominates on the sacrum to be the mechanism of idiopathic low back pain (4, 5, 6). The dysfunction in anterior rotation occurs at S3 sacral at the PIIS. Of primary interest, this dysfunction puts a vertical shear on the dual origin of the piriformis muscle and is the cause of piriformis syndrome. It also will separate the sacral origin of the gluteus maximus from it’s ilial origin. More common bilaterally this lesion may cause a reversible pelvic asymmetry (7). A secondary cephalic slippage may occur at S1 ilial and give the appearance of a posterior dysfunction or an upslip, however, this is clinically insignificant. All are easily corrected with a manual maneuver in posterior rotation and the patient can be free of pain within minutes. This is also the cause of pelvic girdle pain during pregnancy.

References to Sturesson’s work are not uncommon in evidence based research and accepted as evidence of an essentially immobile sacroiliac joint. The basic facts are that the sacroiliac joints have subtle, but important movements and function and are the basis of so-called idiopathic low back pain syndrome, which I have described. This is a reversible biomechanical lesion and must be reversed biomechanically. Neurophysiological solutions or classification of idiopathic low back pain are unlikely to respond with instantaneous relief.

1. Smidt GS, McQuade K, Wei SH, Barakatt E: Sacroiliac kinematics for reciprocal stride positions. Spine 20(9):1047-1054, 1995

2. Sturesson B, Selvik G, Uden A: Movements of the sacroiliac joints. A roentgen stereophotogrametric analysis. Spine 14:162-165, 1989

3. DonTigny RL: Sacroiliac 101: Form and Function - A Biomechanical Study. J of Prolotherapy. 3(1): 561-567, 2011

4. DonTigny RL:  Anterior dysfunction of the sacroiliac joint as a major factor in the etiology of idiopathic low back pain syndrome. Physical Therapy 70:250-265, 1990

5 DonTigny, RL:  A detailed and critical biomechanical analysis of the sacroiliac joints and relevant kinesiology: the implications for lumbopelvic function and dysfunction. In Vleeming A, Mooney V, Stoeckart R (eds): Movement, Stability & Lumbopelvic Pain: Integration of research and therapy. Churchill Livingstone (Elsevier). Edinburgh, 2007, pp 265-279

6.   DonTigny RL: Sacroiliac 201: Dysfunction and Management A biomechanical solution,  J of Prolotherapy, 3(2): 644-652, 2011

7. .Tingren J, Soinila S: Reversible pelvic asymmetry, J of Manipulative and Physiological Therapeutics, September 2006        www.scribd.com/doc/53371374/reversible-pelvic-asymetry