True and Apparent Leg Length Testing – The Lying/Sitting Test

The lying/sitting test for evaluation of sacroiliac dysfunction was briefly discussed here in a recent post.  At that time I said we would come back and look again in more detail considering the mechanics involved and how we can make rational clinical interpretations.  The lying/sitting test is a variation of other well- described Kinetic tests for sacroiliac dysfunction.

These most commonly described are:

1)      Hip flexion test in standing (Stork, Fowler or Gillet test),

2)      Forward flexion in standing or sitting,

3)      Hip extension in standing,

4)      Lateral flexion in standing

5)      Rotation in sitting or standing.

The purpose of these tests is to provide a battery of procedures to quantify which sacroiliac joint shows the greatest degree of motion impairment indicative of a “so called” positive kinetic test.  The advantage of performing these tests in non weight-bearing means that other reference points involving the legs can be used to assist in the positional diagnosis.  The principle of the lying/sitting test is that it can be easier clinically to monitor changes in leg length than to monitor specific pelvic bony landmarks during the standing flexion test and therefore provide an additional layer of evaluation to quantify the pelvic position.

The first principle to establish is whether there is a true leg length difference present.  This is best established in a supine position where the iliac crests and ASIS are monitored on the pelvis together with the position of the medial malleoli of both legs.  If the pelvic alignment is symmetrical and there is a difference in the position of the medial malleoli then there is a suspicion of a true leg length difference. This can be further explored by the patient flexing their knees and evaluating the level of the superior patellas from a side view.  If this isn’t clearly visible placing a book or flat object across the top of the knees will demonstrate any inclination and thus alteration in leg length using this test.  Of course the critical issue in determining true versus apparent leg length difference is whether the clinical strategy is to use some form of orthotic device to compensate for the leg length difference and optimise stress distribution.

Patients with a true leg length difference may well need this type of corrective action but patients with an apparent leg length difference do not and the treatment strategy needs to be directed towards optimising lumbosacral and pelvic alignment.  This is a common pitfall in clinical practice and one reason why establishing true versus apparent leg length difference is such an important consideration.

The apparent change in leg length which occurs as a consequence of sacroiliac or lumbo pelvic dysfunction appears to arise from a number of biomechanical factors.  In supine an anterior innominate rotation carries the acetabulum forwards and down (relative to the axis of the SI joint) and therefore makes the leg on that side appear longer.  Conversely a posterior innominate rotation draws the acetabulum backwards and posteriorly (relative to the axis of the SI joint) apparently shortening the leg on the side of the posterior innominate rotation.

The mechanical effects of moving from supine lying to upright are based upon our current understanding of the kinematics of this movement.  In supine lying the acetabular lie anteriorly and craniad relative to the ischial tuberosities.  On moving to the long sitting position from supine flexion occurs initially in the thorax and then the lumbar spine at which point the pelvis starts to rotate forwards and eventually pivots over the tuberosities as one unit.  The acetabular are therefore moved further anteriorly and also downwards so that the legs appear to lengthen equally.  On returning to supine the reverse pattern occurs when the pelvis rotates backwards as a unit with the acetabular moved upwards and posteriorly drawing the legs equally with this movement pattern.

When sacroiliac joint motion is compromised (for whatever reason) these normal mechanics do not apply.  It is thought that the interference with Sagittal plane motion in this test is compensated for by transverse plane rotation whereby the side with the positive kinetic test (dysfunctional movement side) forces a swivelling action to occur about the opposite ischial tuberosity with the blocked side of the pelvis now moving / rotating backwards (transverse plane twisting – probably because the other side continues to rotate forward to end range) effectively shortening the leg on that side.  The reverse is true for a posterior rotated Ilium in which the leg will appear to lengthen in the long sitting position.

We must remember of course that these alterations in joint mechanics may not be primarily indicative of an articular dysfunction but may be a consequence of  myofascial restriction distorting movement patterns.  The clinical prioritisation of targets therefore comes down to a question of judgement on the primary mechanism, treating an apparent articular dysfunction and reassessing within a treatment session or expanding the repertoire of techniques to incorporate myofascial components if clinically indicated.  Myofascial components in the form of mechanical restrictions are easily evidenced by alterations in length / tension with appropriate length tests and in the absence of these findings the implication is of a motor control /strength deficit. Of course the real challenge is quantifying a mixed pattern of dysfunction related to both true and apparent components of a leg length difference but that’s for another day. So the lying sitting test is a useful assessment tool to add to the battery of kinetic tests when evaluating pelvic dysfunction

Enjoy the clinical challenge.

David

GHTime Code(s): 93621 

Technorati Tags: Acetabulum, Anatomical terms of location, flexion, Kinetic tests, Lumbar vertebrae, pelvis, Rotation, Sacroiliac joint, si joint

Motor Learning & Performance

Whilst recently reviewing some information on motor learning and performance for a workshop I was giving I was struck by the systematised approach to evaluation which the movement science profession attach to this discipline so today’s post explores some of these oversights. I also think that recognition of these concepts is important to integrate into physiotherapy practice to enhance our treatment outcomes.

The popularisation of muscle imbalance concepts as the fundamental basis for exercise prescription (wrongly in my view) has lead to the popularisation of a particular theory of motor control originally postulated by Posner and Fitts in 1968.  This theory outlined three stages of control;

Cognitive phase

Associative phase

Autonomous phase.

The elements of each of these phases have been well described in the literature and have become an excepted paradigm for clinical interventions.  However, we must remember as clinicians that this is only one theory of motor control and due to the complex interaction of the many elements involved in motor control, we would do well to consider thoughts of Shumway Cook…

“that motor control theory is a group of abstract ideas about the control of movement which provide the following information;

1) a framework for interpreting behaviour,

2) a guide for clinical action,

3) working hypothesis for examination and intervention and

4) new ideas.”

Profound words indeed.

My recent study on this topic highlighted the following elements:

Motor skill classification:

Motor skills can be classified according to task organisation as:

Discrete skills

Serial skills

Continuous skills.

A discrete skill is one, which is characterised by a defined beginning and end and is often of very brief duration i.e. kicking a ball, throwing an implement.

When a series of discrete skills are grouped together to form a more complicated action these are classified as serial skills suggesting that the order of elements is crucial to successful performance.  There may be a number of sub elements that make up the total task in this case.  Most activities of daily living fit into this classification.

The final category of skills in this system are those organised in a way that suggest no particular beginning or end, these are known as continuous skills and often repetitive or rhythmic in nature and would include activities such as swimming, cycling, walking and running.

An alternative means of classifying skills is by quantifying the relative importance of motor and cognitive elements.  With a motor skill the primary element determining movement success is the quality of the movement itself with less emphasis being given to the perceptual and decision making aspects of the task.

On the other hand, with a cognitive skill the nature of the movement is less important to success than is the decision or strategy about which movement to make.  It has been said that a cognitive skill is one that mainly emphasises “knowing what to do”, whereas a motor skill mainly emphasises “doing it correctly” – Of course the big debate here is what constitutes correctness!!.

Classification by environmental predictability:

Another way to classify motor skills is to consider the extent to which the environment is stable and predictable throughout the motor performance.  Open skill is one that is performed in an environment that is variable and unpredictable during the action.  A closed skill in the other hand is one that is performed in an environment that is stable and predictable.  The open/closed skill classification system emphasises the relative demands placed upon the performer to respond to moment-to-moment variations in the environment.  For skills at the closed end of the spectrum individuals have the potential to evaluate the environment in advance, organise the movement without significant time pressure and execute the action without the need for sudden adjustments.  However, skills which are in the open end of the continuum requires the performer to utilise processes of perception, pattern recognition and decision making to adjust the movement, often in a short amount of time in response to changing environmental conditions.

If we review these three classification systems it is clear that there is overlap and as clinicians we need to consider each system simultaneously when attempting to evaluate a skilled task or the means by which we need to structure our intervention.

I was refreshed at exposure to these concepts and will certainly endeavour to incorporate this framework into my decision making, movement analysis and skills training in the clinic.

Enjoy the clinical challenge.

David.

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GHTime Code(s): nc 

Technorati Tags: Cognition, Control theory, Decision making, Motor skill, Perception

Pelvic Asymmetry and Leg Length Difference

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

GHTime Code(s): nc nc 

Technorati Tags: lying - sitting test, sacroiliac counternutation, sacroiliac dysfunction, sacroiliac joint dysfunction, Sacroiliac nutation, sacroiliac strain

Is this helpful?

I was caught by the article headline in January’s edition of the Journal of Bodywork and Movement Therapies to which I subscribe and assist with editorial duties.

‘Relationship between handgrip isometric strength and Isokinetic moment data of the shoulder stabilisers’

My initial curiosity was aroused by the idea that it would be a useful exercise in clinical practice to evaluate handgrip strength in patients presenting with shoulder pathology.  My initial reaction was somewhat cynical as I took the view that even if there was a correlation between handgrip strength and Isokinetic shoulder strength data, it is highly unlikely in practice that one would ever use a grip strength measure as a substitute for assessing scapular stability.  This article did indeed go on to demonstrate that there was a correlation which had been noted in previous studies, but I couldn’t help thinking ‘so what’.  The argument was presented that because Isokinetic strength testing equipment is costly, laborious and time consuming an alternative strategy of using handgrip strength measure would be an attractive alternative.  Whilst this may well be the case, I would be curious to know if any of you would confidently rely on grip strength as an assessment of shoulder muscle function?

Of course we know the upper limb functions as an integrated unit with scapular control being an essential prerequisite for prehensile tasks involving the hand, but I am left wondering whether this was just research for the sake of research rather than answering a useful clinical question or influencing practice.  I raise this issue here, not to be critical of the authors (one of whom I know very well over many years), but to raise the wider issue of the direction in which academic journals are taking and the increasing trend for academic institutions to produce a target volume of research in order to secure funding regardless of the practical relevance in the real world.  I don’t want to enter the traditional debate of clinicians being delusional, egotistic and self-serving and academics being cocooned in an ivory tower because it’s a circular debate. Rather I would make a plea for research to be clinically focused or at least leading to some practical application. I do not subscribe to the view that learning research methodology for the sake of education is a worthwhile objective. If it is relevant to learn the true scientific method then it is equally relevant to apply it to something worthwhile.

I vividly remember one of my research supervisors many years ago suggesting that I alter my clinical research aspirations on the grounds of subject difficulty, non-cooperation, data corruption and compliance and stick to cadaveric work. This I dutifully did but doubt I contributed much too clinical management!

I, like many of you no doubt, have been in a position of undertaking clinically focused research, only to realise the complexity of the challenge and arrive at the conclusion that clinical research is hard, challenging and often needs to be done in bite size chunks as part of a collaborative program often extending over years.  As clinicians we often focus on seeking specific answers to questions, which we observe routinely in practice, only to discover that the research methodology required involves multiple stages to address the specific components of a complex hypothetical challenge.

What is also becoming more prevalent is that the opportunity and environment for expression of opinion is becoming more and more stifled, because unsubstantiated comments and opinions do not get past editorial evaluation.  In fact this was one of the main reasons why I started writing this blog and I would love to hear your thoughts and opinions.

Am I being harshly critical?

Should clinicians have a forum to express their ideas and concepts with the expectation that they maybe challenged or provide a basis for future research?

Should we wait for research to provide all the answers and not discuss clinical reality until there is a sufficient body of evidence to inform the debate?

Let us know what you think.

Enjoy the clinical challenge.

David.

Technorati Tags: clinical applications, clinical research, handgrip strength, isokinetic testing, journal of bodywork and movement therapies, research methodology, shoulder stabilisers

GEOFF MAITLAND – A TRUE PIONEER

It is fitting to pay tribute to Geoff Maitland who died recently in Adelaide, South Australia.  Geoff was a pioneer in manipulative physiotherapy.  He gave his name to one of the most widely used manual therapy concepts around the globe today.  Although his primary clinical interest was in musculoskeletal dysfunction, he can certainly be credited with developing a systematised subjective examination which is used across all physiotherapy specialities.

It is perhaps this ability to systemise the subjective process, the clinical examination and the treatment selection, which are the real legacy of this true pioneer.  I had the privilege of working and meeting Geoff and his wife Anne on several occasions and had the fortunate experience of working on a three day video shoot for a clinical teaching module back in1991. He was a truly humble man whose general demeanour gave no indication of his achievements.

Most who trained in these shores would have been introduced to the Maitland concept as an integral part of undergraduate teaching of musculoskeletal practise.  As an enthusiastic (but somewhat naive) new graduate I remember the mental conflict I experienced when trying to understand Maitland’s classic concept of the “semi permeable brick wall” regarding diagnosis, pathology and clinical findings.  In fact if I am totally honest I was a little dismissive of this idea, which at the time I thought was somewhat woolly, non- specific and a little vague.  Such was my disillusionment that I enrolled in a six month Orthopaedic Medicine training programme which taught the principles of another pioneer James Cyriax.  What appealed to me at the time was the preciseness if somewhat dogmatic nature of Cyriax’s teachings, which appealed greatly to my thought processes at that time.  As the clinical mileage began to increase it became increasingly clear that precise diagnostic patterns were the exception rather than the rule and that my search for a definitive diagnosis based on clear cut symptoms and history were a little fanciful so say the least!

This realisation redirected me back to the more fluid clinical approach, which was such an integral part of the Maitland concept.  This prompted further exploration involving study in Perth, Western Australia in 1990 and remains a core component at my clinical practice, twenty years later.

In these days of multi-structural treatment and integration of concepts the focus on pure manual therapy techniques has moved down the agenda to some extent.  The proverbial “chicken and egg” debate regarding muscle dysfunction causing joint pathology or visa versa is a circular debate.  The clinical reality is that we need tools in our armoury to address these components whatever way we arrive at a system of prioritisation.

To address this Maitland postulated a concept of dysfunction based on:

new use

abuse

disuse

overuse

classification system, which I think all clinicians would do well to bear in mind when assessing any musculoskeletal presentation.

One could be critical that the Maitland system did not teach direct muscle treatment strategies or focus on movement re-education as part of a patient management strategy but it did leave us with an unbelievable rigorous system for evaluation and treatment of joint dysfunction using manual therapy techniques.  Developing the manual therapy skills to assess, treat and exclude joint dysfunction as a component musculoskeletal impairment is an essential daily requirement for every clinician.  It is hard to see how one could dispense with his work if we accept the need to directly treat joint’s exhibiting dysfunction.

A contemporary, Freddy Kaltenborn, simultaneously devised a treatment system based on joint mechanics and accessory motion but in reality much of this fundamental biomechanical understanding was integrated into the Maitland approach. Although Maitland’s writings did not expand in detail on pathology he cleverly integrated manual therapy provocation / exploration tests which could readily identify dysfunction – even if the diagnostic accuracy was not a high priority. As it often boils down to assessing treatment response this is the most practical clinical approach which is true scientific method using comparable sign’s and pre / post-treatment analysis of relevant patient markers. Is this not evidence based practise in its purest form?

I for one am very grateful for his dedication and commitment to the profession and hope he retains a watchful eye in his final place of rest..

Enjoy the clinical challenge.

David

Technorati Tags: cyriax, diagnostic classification, Geoff maitland, Kaltenborn, Maitland, manual therapy, manual therapy concept, movement diagrams, semi-permeable brick wall

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