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Sacroliliac joint dysfunction

The sacroiliac joint once was thought to be a joint that had no significant movement and function. I recall occasions in our multidisciplinary meetings just a few years back where even reputable doctors and radiologist have doubted this joint's significance.

Even though there have been multiple studies detailing the anatomy of these joints it is relatively safe to say that its mechanics are still poorly understood and questioned as it is hard to accurately quantify its range in a living subject.


Differences in the geometry of the auricular and axial areas. Corresponding numbers depict both the right and the left SIJ. Note the large intra- and interindividual SIJ differences (reprinted with permission from Bakland & Hansen, 1984).


Andrew Vleeming examined the different shapes and auricular surface orientation of many different cadavers and found a huge deviation between them. Not only the width and length of the auricular surfaces of the greater and lesser arms were considerably different, their orientation relative to the horizontal and vertical planes varied. Sometimes the lesser/short arm was greater than the greater/long arm of the joint, sometimes it was the other is compared to the shape of a letter L was consistent and even though there were differences between their orientation relative to horizontal and vertical planes the deviations were consistent.


Given the logical assumption that primarily joint surface shape and orientation determine the available movement within the joint (arthro-kinematics) with a secondary check from the capsule and ligamentous apparatus surrounding it, the question is not whether there is a significant enough movement that exists in these joints but in what direction and to what degrees. This is something that seems to be very hard to accurately quantify. I believe that the knowledge of relational anatomy of the pelvis is essential in understanding, palpating and interpreting what the hand is picking up of the SIJ's small but impactful movement.


To date, I haven't come across a better explanation, with such logical anatomical and biomechacanical reasoning of how the sacroiliac joint moves, correlating it to everyday clinical presentations than the one in Guy Voyer DO's teaching. In fact, I have witnessed hundreds of patients being treated by him based on his mechanical understanding of the sacroiliac joint and the results were exceptional. Many of these people had previously exhausted all other rehabilitation methods and medical treatments, including surgery with limited success. But their body turned often immediately when treated based on this understanding. Seeing this made me decide to start doing Voyer's osteopathic training.



The sacroliliac joint functions as a connecting rod a sort of "shock absorber" that transfers the ascending ground forces through the movement of the lower limbs to the trunk and the descending forces generated by the trunk and the upper limbs to the lower limbs.





These forces are not aligned in any way. From a sagital view the descending forces coming via the sacrum are posterior the ascending forces coming from the femoral head. In frontal plane view they are medial to the descending forces.





The SIJ and its ligamentous apparatus absorbs and transfers those forces from lower to upper body and vice versa.







The body trabeculae are bony deposits, a sort of internal bony reinforcement of the bone that build up in relation to the pressure and tension imposed on the bone. These internal pillars are continous and can be seen as a representation of line of force transmission inside the bones as well as bone to bone. Collagen fibre orientation inside joint capsules and ligaments often look c

Trabecular alignment coming from the sacral vertebrae and continues in different lines towards the ischial tuberosity, pubic branch and the coxa-femoral joint from where it continues to the femoral head, neck and the shaft etc.

The SIJ is a transfer of these forces and the line of tension represented by the bony trabeculae forms in different joint position in relation to the ilium, ischium and pubis. If joint alignment is disrupted, trabecular continuity will be disrupted too, which asks for remodelling in relation to the changed loading. We know the importance of trabecular alignment in the case of joint wear and tear and osteoarthritis.


In order to have a basic understanding of SIJ mechanics we need to have a quick look at the anatomy surrounding the joint.



The joint surfaces that articulates with one another are called the auricular surfaces. The short arm or lesser arm runs antero-inferiorly and its orientation is closer to the vertical plane. The long arm or greater arm of the SIJ is running antero-superiorly and its orientation lies closer to the horizontal plane. The two arms meet at the isthmus forming a shape resembling a letter "L". The end/tip of each arms are called the apexes, while the root of each arms called the bases. The isthmus is the most anterior part of the joint where the two arms meet.



Basic review of the Axis of the Pelvis & SIJ

It is important to note that I'm not saying that these are the only movements possible. What I'm saying is that based on Guy Voyer DO's 40+ years of clinical practice and vast experience these are the movements that have proven to be the most accurate representation of the how these joints may function.


The 22 virtual axes of the pelvis

3 horizontal axes

2 oblique axes

9 AP axes

5 vertical axes

3 axes of the pubic symphysis


While this sounds a bit of a mouthful it is important to understand that the first 5 are physiological axes while the rest are pathological movements as a result of restriction due to, muscles spasm, osteophytes, arthritis, cysts, visceral lesion just to name a few. The body's goal is to always complete an oblique axes and the pathological axes are compensations of the body trying to move normally with the given restriction. These pathological axes are in line with or are assigned to the various landmarks of the joint and are 'acted out' as compensatory mechanism in the body's attempt to continue to move in the path of least resistance.


The horizontal (H) axes run in the frontal plane.

H1 is at the level of the first sacral vertebra and it is Sutherland's cranio-sacral movement - (sacrum-occipital)

H2 is the movement of counter-nutation and nutation as the superior and inferior pelvic outlet opens during delivery.

H3 is the movement of the ilium in posteriorization, anteriorization, inflare and outflare relative to the sacrum and it is called iliosacral movement.

Anteriorization and posteriorization are both movements of the ilium in the sagital plane. Inflare and outflare are similar movements of the ilium with an additional component of flaring - which results in a slight frontal plane deviation where the ASIS moves medially with outflare, and the PSIS moving medially with the inflare.


I've heared that terminology of inflare and outflare may be taught slightly differently in other schools pf thoughts so it's worth keeping in mind.

These are physiological movements that happen in conjunction with the sacrum's movement on its oblique axes.




The oblique axes run from the apexes of the lesser arm to the controlateral apex of the greater arm. This is a sacroiliac movement or the movement of the sacrum relative to the ilium. The sacrum performs the movement of positive torsion (flexion+rotation) and negative torsion (extension+rotation).

During gate the sacrum moves from positive to negative torsion and the ilia move between inflare and outflare. These are physiological or healthy movements of the pelvis.


Now imagine you had a harder than usual workout where you loaded a bit heavier than you should have. You happen to be on the more mobile end of the mobility scale and the next day one side of your lower back feels very stiff. This stiffness comes from a small spasm of your right iliocostalis lumborum which when retracted can directly impact the full range of the movement of the ilium into inflare, just as a tight biceps would limit the degree you could fully straighten your elbow.


This has a knock on effect of the surface area the femoral head engages the acetabulum, therefore, the ligaments of the hip joint, the rotation range of the femor, therefore the knee and so on going down the chain. Not to mention the anterior ilium will create a false long leg on the side as the femor is pushed inferiorly with a component of relative internal rotation. The sacrum will side-bend and the lumbar spine will have to adopt and so goes up the chain to the thoracic spine, scapulae and cervical spine.


Our muskuloskeletal system serves as a container in which our visceral system exists. Lot of the organs are literally suspended between these bony levers and when the position of these bones change, the tension of these suspensory ligaments of these organs can create a tension, torsion or create a position that results in compression which can result in altered function overtime. Just think of the lumbo-ovarian ligament, the utero-sacral ligement or pubo-vescical ligament where the ovaries, uterus and bladder rely on an ideally symmetrical pelvis. This is one very simple example that's meant to remind us to the importance of looking at relational anatomy and its functional physiological correlations.


What isn't normal

Pathological axes develop as a result of trauma, micro-trauma or prolonged imbalances mainly on the apexes and bases of the lesser and greater arms as part of the compensatory mechanism of the body trying to move normally. The sacrum wants to complete its positive and negative torsion and the ilia want to move into inflare and outflare.


The following axes are non-physiological, where normal torsional movement of the sacrum is not possible that results in an abnormal movement as a compensation.


Antero-posterior (AP) axes - a restriction of mobility on either the apexes or bases of either the lesser or the greater arms and there is a central AP axe that goes directly in the middle of the sacrum = 9 AP axes

Meaning the sacrum wants to do a positive torsion (flexion+rotation) or negative torsion (extension+rotation) on the oblique axe but there is a restriction of mobility on the base of the greater arm (this creates an axe that will disturb the normal torsional movement of the sacrum and will likely to result in an additional abnormal side-bending of the sacrum.


Vertical Axes - these are restriction of mobility at the end of the range in the apexes of either the lesser or greater arms with one central axes - 5 Vertical axes These lesions are very painful and often results in "spraining" the posterior sacroiliac ligamentous complex and/or the pubic synthesis.


The axes of the pubic symphyses. In reality these axes don't exist. They are lesion on planes of movement, in which there is a mixing of axes as a consequence of one of the above lesions.

These are movements of necessity as a result of compensation, never pure movements.

1. Sagital plane: superior and inferior movement of the pubis symphysis.

2. Horitonal plane: anterior and posterior movement of the pubis symphysis.

3. Frontal plane: There is a torsional component to the movement through the meniscus and interosseous ligaments.






The above are just a brief explanation of some of the possible pathological movements of these joints. These lesions can happen simultaneously where the combination of two exists as the body's compensation will create a secondary lesion.


In my experience it is very hard to find someone suffering from virtually any type of back, hip, knee or foot and ankle problem with a perfectly aligned sacroiliac joint. Many of these cases where the SIJ is corrected the pain itself will reduce in intensity and in some cases disappears completely.


SomaTherapy treats pelvic, sacroiliac joint and pelvic floor dysfunction with specific manual therapy techniques that normalise each part of the joint and its biomechanically significant ligamentous, fascial and muscular links. Treatment comes hand in hand with exercise therapy where very specific exercises are given/taught to target the very tissue that's been treated.


Look at SomaTraining exercise therapy as a mini treatment, a type of self administered version of the treatment in micro-dosing that you can do yourself at home. These techniques are very powerful and give the steering wheel back into your hands where you gain control back over your health.






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