The sacroiliac joint has now been well established to actually move yet clinicians of my generation and older would certainly be aware of the argument that the sacroiliac joint did not normally move except in pregnancy.  Suffice to say that we have now moved beyond this argument for the normal population and the clinical challenge is diagnosing not only the existence of sacroiliac dysfunction but the mechanism behind the dysfunction.

Radiological imaging does not particularly add to the diagnostic work-up so we are left to rely on clinical assessment.  In the last decade Vleeming and Schneider’s have advanced the concept of both “form and force closure” as the primary mechanisms maintaining sacroiliac stability.

Form & Force Closure

In brief, form closure refers to the configuration of the joint surfaces, the alignment of these surfaces relative to gravity and bodyweight, and the tension in the restraining ligaments associated with normal alignment of the segments.

Force closure refers to the interaction of multiple muscle groups, which act across the joint to enhance compression on the joint surface to assist in joint stability.  This is the so-called oblique sling system, which has been conceptualised to involve the ipsilateral Glueteus Maximus and Tensor Fascia Lata in conjunction with the contra lateral latissimus dorsii.  This is enhanced anteriorly by the oblique abdominal system and the contra-lateral hip adductors.

These two oblique systems effectively form an X  (cross shape) on the anterior and posterior aspects of the pelvis and constitute the dynamic mechanism by which joint integrity is maintained.  These concepts appear to hold some clinical validity and have provided an enhanced framework for us to approach our treatment of the sacroiliac joint.

Lee has integrated this approach with some of the traditional osteopathic models to provide a clinical algorithm for determining sacroiliac dysfunctions. This involves evaluation of:

1)      Lumbar spine

2)      Pelvic landmarks,

3)      Sacral landmarks.

This provides a practical framework where we as clinicians can try to differentiate primary or secondary pelvic dysfunction and therefore target our treatment in the most appropriate way.  Because of the functional interaction of body segments a lumbar scoliosis, for example, can have secondary effects on the sacroiliac joint alignment and conversely sacroiliac mal-alignment may produce secondary scoliosis in the lumbar spine.  This is the classic “chicken and egg” scenario.

So using the above categorisations we can quantify spinal alignment using:

Visual observation

Palpating bony landmarks

Correlating with movement pattern in the lumbar spine.

Looking specifically at the pelvis we can define the position of the bony landmarks on the pelvis using:

ASIS,

PSIS

Ischial tuberosities

as reasonably reliable landmarks to assess the positional orientation of these bones.

The spectrum of pelvic dysfunctions which have been described include:

Anterior innominate rotation

Posterior innominate rotation

Innominate inflare

Innominate outflare

Innominate upslip

Innominate downslip.

Much debate exists regarding the reliability and mechanism of these syndromes so it is largely a clinical diagnosis.

The principle assumption of quantifying bony pelvic orientation is that the pelvic position will determine the position of the sacrum and therefore mal-alignments of the pelvis should be prioritised over sacral mal-alignments when they are observed to co-exist.

Corrective Measures

In general the principles of correction are either to use manipulative thrust procedures, joint mobilisation or muscle energy / myofascial techniques to help to realign the pelvic structures using the leverage of the torso or lower limbs.  This then leaves us in a situation of assessing the sacral position within the corrected pelvic rim and then ascertaining the sacral orientation. A number of sacral dysfunctions have been categorised.

These include:

1)      Nutated sacrum

2)      Counter- nutated sacrum

3)      Oblique axis twist indicating a spinning mechanism where one side of the sacrum lies deep and the other lies more superficial.

Assessing sacral position within the pelvis is challenging clinically, produces more inter-tester variability and is harder to be confident with.  However it is well worthwhile using this clinical algorithm to define  joint mal-alignments clinically and plan treatment strategies.

Crossing the first hurdle of defining the dysfunction the challenge is then to determine why mal-alignments have occurred and whether we can assess breakdowns in functional control (force closure mechanisms) which may be associated with overload- but that’s another day’s work and a discussion for another time

.

Enjoy the clinical challenge.

David

© David for PhysioDigest - an educational resource for the musculoskeletal rehabilitation community, 2009. | Permalink | 2 comments | Add to del.icio.us
Post tags: Anterior innominate rotation, form & force closure, Innominate downslip, Innominate inflare, Innominate outflare, Innominate upslip, Posterior innominate rotation, sacroiliac, sacroiliac joint dysfunction, sacroiliac strain, vleeming

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