The pelvis is a unique structure. It functions as (at least) the major site of load distribution in the human body, the transition point between thorax and lower limb, the container of the lower abdominal viscera and the origin of new life. Its shape is complex, bilaterally symmetrical and beautiful. When one looks about at those around us, it is clear that this structure is being employed in many different ways. As SI practitioners, it is vital for us to understand how.

In the literature, the concept of “pelvic distortions” is, for the most part, limited to the basic notion of tilt (anterior or posterior) on an axis running through both acetabula, occurring in the frontal plane. This is an important concept, as it provides an understanding of the response of the spine, in compensation, to adjust the load of the thorax over a variety of centerlines. Grasping this, it becomes easier to see and understand a clear cause of lordotic, kyphotic or too-straight spines and, furthermore, to see why treatment of these problems, when they become symptomatic, needs to address pelvic position instead of simply the spinal segment screaming at the time. This was the state of the art for a long time.

The anterior / posterior (A/P) tilt view, though, was limited in its explanation of A/P curves only. Side-bending was not addressed. When this issue was mentioned, it was casually explained away by a pelvic tilt in the frontal plane, in this case meaning one side of the pelvis sat lower in space than the other. More recently, in manipulative and sports medicine particularly, it has been more satisfyingly noted that the innominate bones might, in fact, be counter-rotated with respect to each other. This was recognized and studied most often after a traumatic blow – especially when there were neurological consequences. SI, in a more unique stance, notes this lack of perfect bilateral symmetry, or torsion by degree, as the norm.

The innominate bone rolling further anterior on its transverse axis takes the sacral base on the same side anterior and caudad, pulling the whole sacrum into a rotation away from and a tilt toward that side. Of course, the lower lumbars (at least) follow suit. The sacral rotation about its longitudinal axis and the side-bending resulting from the asymmetrical sacroiliac joint positions in these cases was, in turn, seen as a component of lumbar side-bends and rotations and even scoliosis, requiring a cascade of compensations both up and down the structure. As SI practitioners, we treat the entire pattern, leaving the designation of this pelvic reality as causation or reaction to our own musings. It is the purpose of this paper to take this understanding to the next level.

Intra-Innominate Distortion

During early development, the innominate bones are really three distinct bones (ilium, ischium and pubis), which subsequently fuse into each innominate bone. Interestingly, we consider these three regions commonly as a sort of “cluster in agreement,” while we consider the five bones of the sacrum as a single bone in all but technical definition. Why do we do this? The cranium, which is (in allopathic medicine) considered fused over early development although sutures between the bones remain visible, is always referred to regionally. In many forms of complementary/alternative practices, the cranium is not only considered to be composed of distinct, interconnecting bones, but is palpated and treated in order to optimize relative bony positions with conscious attention/intention given to the tensional relationships of (for instance) the falx, tentorium, cranial fasciae and associated external contractile elements. In other words, in these modalities, the cranium is not seen as fused at all. I propose here that the pelvis acts differently in its six regions, even though joints (other than the sacroiliac joints and pubis symphysis) are not clearly present. Indeed, unlike the cranium, each fused innominate bone appears to be a single unit. It is proposed that the pelvis is a unique, internal flexible structural element that is designed to adapt to the tensional needs of the individual.

In the breadth of SI, there has been much offered to shed light on the variability of the pelvis and its relation to upright structure. Rolfing practitioners Hans Flury, Jan Sultan and Liz Gaggini have all offered their understanding of this to the practitioners at large, vastly improving the efficiency of SI. Gaggini, in her biomechanics text, explains how the innominates counter-rotate, taking not only the femurs with them, but also the entire structure. She explains the need to first restore congruity to the pattern and then reduce that pattern’s amplitude. The corrective strategy is based on the methodical manipulation of the fascia associated with specific muscles in order to restore optimum function to the whole structure.

Dramatic structurally anomalous patterns go further. For instance, scoliotic patterns (in their many forms) and dysplastic hips go to heroic lengths to keep themselves upright. SI practitioners, employing the strategies offered to date, just don’t go far enough, and in some cases, not only don’t go anywhere at all, but seem to go backward. What could be wrong?

Classically, motion of segments is thought of as motion available at a given joint, within that joint’s capable range. For example, in consideration of the pelvis as a whole, we can imagine rotation anteriorly or posteriorly about the transverse axis of the acetabula in much the same way as we can imagine a suspended simple pulley, rolled forward or back on its axis by a rope threaded through it (see Figure 1). Pull on the “back” rope and the pulley rolls backward; pull on the “front” rope and the pulley rolls forward.

Well, we assume here that all is free and clear; i.e., the motion of the pulley is free from tensions or restrictions. That’s a big assumption. In SI, it is vital to remember that this is not the case. For motion into a pattern, the opposite “rope” must have enough play, or give, to allow motion to occur. Given muscle tonus and especially when a subject is not supine and at rest, tension is always present. This is what creates dynamic balance about a given joint, so it is not inherently bad. With a balanced tensional load, appropriate to the system design, the motion is in a dynamic tension and operates with reasonable freedom. As the tension increases, so does the pattern. For instance, with a classic anterior tilt pattern, the “front rope” bits are tighter than the “back rope” bits, causing the pelvis to be anteriorly rotated on the acetabula even when at “rest.”

If the tension is increased beyond the bending load limit of the bone at that point, the expectation would be of tendinous rupture, as is the case occasionally seen with the calcaneal or biceps tendons. The attachments of these two tendons are on bones that are long and thick, offering substantial bending resistance, which is clearly higher than the rupture limits of the tendons in question. The pelvis, however, has a unique shape and conformation, allowing for other dimensional possibilities. For instance, going back to our pulley metaphor, consider the effect of pulling the rope slightly out of line with the rolling axis of the pulley. What happens if the rope tension is pulled to one side or the other of the rolling axis of the pulley? If the tension is increased enough, the pulley rolls toward the direction of pull along its transverse axis (Figure 1).

<img src=’https://novo.pedroprado.com.br/imgs/2008/948-1.jpg’>
Figure 1

It is proposed here that the thin-bodied ilia have bending load limits lower than the rupture limits of their major attachments. In this scenario, there is bony distortion as well as large increases in compression (Figure 2).

<img src=’https://novo.pedroprado.com.br/imgs/2008/948-2.jpg’>
Figure 2

Let us now use an additional metaphor. Anyone who has ever repaired a flat tire on a bicycle can easily attest to the similarity between the crest of the ilium and a bicycle rim. The thickened flare of the superior crest not only allows for substantial fascial attachments from above, but also allows for attachments (internal or external to the crest) from below to approach its center – much the same as spokes fasten to a bicycle rim. Trueing a wheel is a balancing act, as is suspending, while loading, the pelvis. As imbalanced spoke tension can easily distort a wheel, so perhaps can imbalanced fascial tension distort an ilium, especially since the bone is so very thin. It is this type of distortion that will be addressed here. Apparently, it is far more common than one would expect, and because it greatly increases the incongruity and complexity of a given structural situation, it must be dealt with first.

In somewhat ambiguous patterns, it is easy for practitioners to fixate on flare patterns of the ilia. They are a clear clue, after all, and in-flares are classically congruent with anterior rotations, while out-flares are congruent with posterior rotations. Complicating things are the coexistence of out-flares (for instance) with medially rotated femurs. These out-flares might be extreme. What is the truth here?

Well, if time is really taken to understand what is going on, it becomes very clear that while the ischium and pubis might be going anteriorly, the ilium may frankly be out-flared. In other words, what might be an anterior innominate might have within it an out-flared ilium. In some cases, this can actually be seen on X-rays, if available.

The lower aspect of the ilium might curl extremely medially while coexisting with a visible out-flare above.

Furthermore, the implications of this quickly progress to the ilio-femoral joint itself. As a joint enjoying three degrees of freedom, it is capable of positional changes to accommodate complex changes in the position of the femoral head within the acetabulum. However, the issue becomes far more threatening when one realizes that before fusion, each of the three bony regions of each innominate bone join in the acetabular cup, with each bone taking up roughly one-third of the surface area. Given the deformable characteristics of live bone, it is simple to visualize how the acetabulum can be distorted by this pattern conflict. Considering the epidemic incidence of joint replacements, this realization has immediate application.

From the perspective of the acetabulum, having the umbrella of the ilium able to take so many shapes above and around it, dragging with it all of its connective tissue, could be a fertile source of increasingly common impingement problems.

Furthermore, one must wonder what the possibilities of resolution are post joint replacement, when a conflicted innominate has installed within it a perfectly machined cup and femoral head. Can the innominate shape and normal tension be restored?

It becomes easiest to visualize an example of these distortions first from above. From this perspective, it is clear that the ilia can be distorted (with enough tensional load) in a direction out from the central axis of the pelvis or even in a caudad direction. But to bring a neutrally flared ilium toward the central, vertical axis of the body would require a pull from the center – or a distant pull from something more near the centerline than it is (i.e., the diaphragm via the abdominal fascia). The iliacus, though its myriad fiber directions originating on the inside surface of each ilium (recall the bicycle-wheel metaphor), is also able to pull this structure toward the midline. Pulls from the internal organs having ligamentous connections or a high degree of scarring to the pelvis are a possibility, too, although one employing less significant leverage.

In fact, the ilium is a strikingly thin bone in all but its edges, and so not as difficult to overcome in bending load as, say, an ischial tuberosity, which is consistently very thick. Thus, we would expect most distortions to be most easily evident in the ilia. Given that a position in space about a particular joint may always be thought of as a tensional agreement between antagonistic connective tissue elements, those structures restricting motion are as responsible for the distortion as the agonist involved. Therefore, it is necessary to know the structures responsible for normal pattern behavior across joints. When these get too insistent to allow for any other possibility, and the antagonist must increase tensional load, there is distortion.

Once convinced of the pattern disparity, the first task at hand is to bring each innominate into a kind of “continental congruency” before dealing with coarser pattern issues. This requires a more complete, specific and thoughtful assessment of the innominates and is well worth the time taken to do so. Once relative bony position is established, the tensional possibilities involved in a given distortional pattern must be carefully considered and explored. Working this way yields a dramatic increase in overall manipulative efficiency.

The exploration of particular distortional patterns and their associated connective tissue players will be left for a future paper.

The Language of SI

A moment must be taken to address how SI practitioners have evolved to work their art/science over the years. SI is done through the manipulation of fascial tissues. Over time, those fasciae associated with muscles tend to become primary, as clients are more able to understand this language and thus picture the anatomy of what needs to be accomplished. Thus, practitioners get lulled into picturing things this way themselves and look at postural distortions as based on improper symmetry of muscular structures that can be changed by lengthening the fascial tissues enwrapping them.

Within the practice of SI, it is vital to remember that fascia is the organ of form. The SI view of the structure is a plastic one of continuous accommodation, with bones acting as spacers and muscles creating the possibility of movement around bony articulations by acting as fascial tensioners. The vital importance of fascial tissue as a shaper, connecter and keeper of possibility in and of itself needs to be stressed once more. Language is a very powerful tool, and when certain phraseology is employed over time the outcome is a change in interventional intention. Caution must be exercised here.

The author would like to thank her clients for their curiosity and involvement in their structural process. Also, great thanks go to Dr. Stephen C. Brown for his scientific mentoring, his ignition of a spark of this author’s lifelong interest in the field of biomechanics and his very insightful commentary on the draft of this manuscript.