The clinical challenge of differentiating true and apparent leg length difference is not frequently discussed in the literature and is fraught with difficulty.  In general we can classify pelvic asymmetry as;

1) Primary intrinsic pelvic ring dysfunction

2) Asymmetry secondary to lower limb leg length variation

3) Asymmetry secondary to spinal mal-alignment.

The principle of quantifying pelvic orientation is to eliminate the effect of the legs and assess bony pelvic landmarks in prone, supine and sometimes sitting.  This allows for direct comparison side to side and at least the ability to quantify asymmetry. The well described observations include:

Anterior innominate rotation

Posterior innominate rotation

Innominate upslip

Innominate downslip

Innominate inflare

Innominate outflare

Sacral torsion.

These types of classifications allow us to state the positional relationship of the innominate and sacrum but often pose a significant challenge in determining which is the side of asymmetry i.e. is the high side high or the opposite side low?  To evaluate this question the assessment needs to be supplemented with specific muscle length and movement tests to attempt to establish a pattern. The well recognised strategy of using the umbilicus as a reference point allows for easy visualisation and distance measurement but has the drawback of requiring some “normative” distance reference for which there is not a reliable baseline and the measurement error would likely be unacceptable.

Useful bony landmarks for reference are:

Iliac crests

ASIS

PSIS

Ischeal tuberosities

Sacral Sulcus

Sacral inferior lateral angle

Because alterations in pelvic alignment contribute to changes in leg length the clinical challenge of defining what is a real leg length difference , what is an “apparent “ or functional leg length difference and what is a “combined” lesion can be very taxing. This is compounded by the fact that apparent conflicts in findings hamper the reasoning process. For example an innominate upslip produces an apparent leg shortening on the same side but in standing the elevated pelvis can be misinterpreted as a consequence of a long leg on that side.

Anterior or posterior innominate rotation are perhaps the easiest of the pelvic asymmetries to quantify. To answer the question of which is anterior and which is posterior supplemental length / tension tests are really helpful. An anterior rotated innominate is frequently associated with restricted hip flexion either by posterior buttock tension or anterior hip impingement.SLR can also be restricted on the same side.

A posteriorly rotated innominate is frequently associated with restricted hip extension (the prone hip extension test), Lumboscaral facet impingement / Sacroiliac strain and Rectus femoris tightness.

Supplementary manual resistance tests may reveal weakness of the prime movers associated with the alignment asymmetry.

If we consider the inflare / outflare pelvic alignment scenario the most important point to recognise is that anterior innominate rotation is coupled with innominate outflare and posterior innominate rotation is coupled with innominate inflare. Therefore it is necessary to address the rotational mal-alignment as the first priority and having established alignment in the saggital plane then proceed to assessing the “flare” component. An outflared innominate is frequently associated with a restricted F / ADD test either due to posterior buttock strain or medial groin impingement. An inflared innominate is frequently coupled with a restricted FABER test and usually by adductor tightness.

In practise, the initial strategy is to align the innominates and subsequently assess for sacral position. Obviously Sacral mal-alignment may alter innominate position and visa versa but in order to provide a useful framework the above sequence is suggested.

One of the most widely applied differential tests is the lying/sitting test. This attempts to quantify alterations in leg length associated with a change in pelvic alignment and thus differentiate between true and apparent differences.

In a future post we will look in detail at the lying siting test and the factors which influence the test results.

Enjoy the clinical challenge
David

© David for PhysioDigest - an educational resource for the musculoskeletal rehabilitation community, 2010. | Permalink | 7 comments | Add to del.icio.us
Post tags: lying - sitting test, sacroiliac counternutation, sacroiliac dysfunction, sacroiliac joint dysfunction, Sacroiliac nutation, sacroiliac strain

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Lumbar pain on flexion is one of the commonest symptom reports clinicians hear when treating patients low back pain.  There are a number of clinical reasoning processes, which need to be considered.

Pathology

Much of the literature focuses on the changes in intra-discal pressure associated with spinal flexion implying that spinal flexion pain is associated with increased disc strain reproducing symptoms.  In order to strengthen the hypothesis of disc related flexion pain the clinician needs to establish other components of discogenic characteristics to support the hypothesis.

These can range from the overtly obvious…..

gross global movement restriction

spinal shift

radicular pain

positive neuro-provocation tests

neurological signs

to the other end of the spectrum where symptoms are only produced on flexion and only localised in the lumbar spine.  Of course acknowledging that any of the spinal elements may reproduce pain on flexion and this produces a list of potential targets to include:

zygapophyseal joints

supra-spinous ligaments,

intra-spinous ligaments

posterior longitudinal ligament

ligament flavum

local segmental musculature

Symptom Location – clues to aetiology

The ability to localise symptoms can give the clinician some clues as to the possible structures involved, but in cases of centralised pain this does not particularly enhance diagnostic accuracy other than to reduce the likelihood of facet joint involvement.

Treatment

Interestingly typical treatment approaches for flexion related pain is to use extension/McKenzie’s extension protocols, passive accessory intervertebral motion to facilitate extension (Maitland).  Undoubtedly this strategy is helpful for patients when improvements in tolerance for extension related treatments show simultaneous improvement in flexion capacity.  And for those that don’t?…….

What do we do for patients whose flexion does not improve with extension regimes?

The caseload of interest here are the patients who might be categorised as non-specific low back pain who have persistent problems with spinal flexion.  Here is a list of tips for things to evaluate when accessing this function:

1. Spinal segment flexion range.
2. Hamstring flexibility.
3. NeuroDynamic sensitivity.
4. Proximal trunk control.
5. Pelvic rotation on femoral heads.
6. Sacroiliac nutation.
7. Hip extensor muscle function on flexion (eccentric control).
8. Hip extensor muscle function on return to upright (concentric control)
9. Paraspinal / abdominal co-activation on return to upright.
10. Lumbal-pelvic rhythm on flexion.

PS

11. Lumbal-pelvic rhythm on return to upright.

Evaluating each of these components allows the clinician to determine mechanisms of breakdown and plan treatment strategies to facilitate recovery. Exploring these mechanisms is relevant for non-responders to extension regimes.

Enjoy the clinical challenge.
David

© David for PhysioDigest - an educational resource for the musculoskeletal rehabilitation community, 2009. | Permalink | No comment | Add to del.icio.us
Post tags: concentric control, eccentric control, flexion, Hamstring flexibility, intra-spinous ligaments, ligament flavum, local segmental musculature, Lumbal-pelvic rhythm, Lumbar disc, Lumbar pain, NeuroDynamic sensitivity.Proximal trunk control, neurological signs, Paraspinal / abdominal co-activation on return to upright, Pelvic rotation on femoral heads, positive neuro-provocation tests, posterior longitudinal ligament, radicular pain, Sacroiliac nutation, spinal flexion, Spinal segment flexion range, spinal shift, supra-spinous ligaments, ygapophyseal joints

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