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Preface

Posture

Posturology

The case study

The backstage

Bibliography

Definition | Features | Physiology | Pathology | Etiology

Posture

Posture has been defined in a thousand ways, none of which compliant to the intended meaning of the author; the absence of agreed conventions leaves the boundaries of the subject still ambiguous and undefined, as such, explanation of the concept by each author, prior to expose it, is a prerequisite.

In order to provide general meaning to the word posture, including all the variables that it implicitly involves, it is mandatory to remark that posture may NOT be confined to human beings, NOR to upright position and NOT EVEN to awake state or to other contextual restrictions.

Posture is the shape, position and motion of live beings equipped with motor system, it's goal is to describe the way motor system implements all hierarchical layers of motion:

1. reflexive motor vital functions (eg. respiration, heartbeat, swallowing..)
2. reflexive motor vital defence (eg. cough reflex, gag reflex, vasoconstriction..)
3. reflexive motor environmental tasks (eg. stretch reflex, crossed-extension reflex..)
4. spontaneous motor environmental tasks (eg. congenit motor abilities like walking..)
5. voluntary motor environmental tasks (eg. acquired motor abilities like skiing, striking poses..)

Posture precise description is achieved by a bidimensional matrix resulting by the cross-correlation of being classification and motor model.

To achieve a being classification, the sample has to be catalogued according to individual features within it's breed:

• age/gender/anatomical
• environment/behaviour
• health/pathology
• other

To achieve a relyable motor model the avaulation has to be performed under as many perspectives as possible in order to have all the variables included, measurable and reproducible:

• self/other evaluation
• insideBody/outsideBody evaluation
• visual/instrumental evaluation
• static/motor evaluation
• awake/asleep evaluation
• single/repeated evaluation
• lab/environment evaluation
• other

Putting being classification and motor model together we get the postural model of the evaluated individual.

Implementing classes of postural models allows to contrast an individual postural model with a mean postural model within it's species or species parameters (eg. same age, same gender, same anatomical features...) and to understand variations amongst individuals/race/gender/age/pathology or whatever other perspective.

Within this broad definition, the material hereafter exposed covers human posture and the symptoms, mechanics, pathomechanics and etiopathogenesys of the postural disorder.

Features

Posture internally acts on each part of human anatomy in different ways: provides life, defence, motion and degeneration; every motor system action generates both immediate (motion) and delayed (degeneration) responses. Basic requisite to approach the hypothesis and observations hereafter exposed is the agreement and understanding of author's perspective.

Postulates of posture:

1. Functional hierarchy: with life preservation as the priority, meaning that postural strategy never conflicts with higher priority functions. Understanding this is mandatory to interpret each pathological behaviour;
2. Crafted by natural selection: meaning that every postural strategy comes out from million years of human anatomical/environmental relationship evolution, thus, neither meant to manage each anatomical/environmental combination (eg. white bear in the saharan desert) nor to adapt to new environments (sitting at a desk) nor to diffused aberrations (high heels, wrong medical therapies) never experienced during human race evolution (all of which situations most of civilized human beings indeed experiment). Understanding this, helps explaining such a high incidence of postural strategy failures causing pathologies so uncommon in the less civilized human and animal beings.
3. Dismantled by loss of natural selection: meaning that pathologies are growing as natural selection has been interrupted thousands years ago, at least in civilized world, given to the loss of selecting conditions, as such, unsuited and pathologic characters are transmitted to the progeny contributing to weaken global mankind strenght and health.

Variables of posture:

Priority dependence:

• systemic functions,
  • basal functions
• motor functions
  • life preserving motor functions (respiration, alimentation),
  • simple motor functions (walking),
  • complex motor functions (playing, dancing, speaking);

Anatomy dependence:

• race and gender (different anatomical conformations),
• age and degeneration (different resources requirements and availability);

Internal stimuli dependence:

• proprioceptive receptors (providing somatic stimuli),
• nociceptive receptors (providing pain stimuli),
• exteroceptive receptors (providing external stimuli),

Environmental stimuli dependence:

• external forces (gravity, wind, impacts.),
• chemical (atmosphere, water, heat),
• social (causing instinctive behaviours, sexual, supremacy),

Task dependence: static, motor, difficulty;

History dependence: learning ability;

Awareness dependence: awake, asleep, REM sleep.

Physiology

Physiologic posture is the way human evolution has developed postural strategies to accomplish all the tasks human body is requested to, thus, it merges common functional (objective) and individual (subjective) criteria together with environmental characteristics (variable), making challenging drawing rules for prototyping it. Plenty of parameters, along posturology short life, have been theorized to describe physiologic upright position and/or other common postural position in order to identify every possible deviation from what is considered normal, this catalogue of observations is the first logical stage to get a physiologic posture model but is considered way far from being completed.

The most intuitive way to draw a physiological motor model is entrusting the sampling criteria to natural selection itself (or what's left of it). The measure unit of motor functionality is the motor outcome, in other words, the motor performance level, which can be described as:

• Quantitative: objective motor outcome in terms of speed, power, endurance....
• Qualitative: subjective motor outcome in terms of motor aesthetic, harmony, style, techinque...

Suitable criterias for identifying segments of population meeting requisites of motor physiology are: occupational and etnic.

Occupational segments of population are, in order of relyability:

1. Classic ballet etoile: the incredible technical difficulties requires the highest functional level, the further restrictive aesthetic requisite makes a high level ballet artist the most relyable specimen for physiologic motor model, meeting either quantitative and qualitative motor performance levels.
2. Top level (absolute level) athletes in every specialty: the level of measurable performance reached makes these athletes quantitatively superior, whereas, their repeatable and undiscussed superiority allows to consider them either quantitatively and qualitatively superior,
3. High level athletes and classic ballet artists: they offer a good likelyhood of posture physiology but not as high as the above, the relative level reached doesn't allow to exclude the presence of some extent of postural disorder.

Etnic segments of population are considered a higly relyable way to draw a physiologic motor model, segments identification is challenging and require a wide statistical base, according to observation the author proposes:

1. Black etnies from poorly civilized africa: the presence of environmental selecting condition, the lack of economic resources and the low likelyhood of ratial contamination, contribute to enforce this population by means of natural selection,
2. Other etnies from less civilized worlds: same as the above but extended to other etnies.

Despite the apparently reductive criterias for targeting the population, it is opinion of the author that sampling controls according to relyable predetermined categories reasonably yields a set of physiologic motor models, as such, collecting each sample’s anthropometric motor and static features would provide a relyable being classification and related physiologic motor model.

In the absence of relyable parameters to which entrust the definition of physiologic posture, not only simplifying is restrictive but it may reveal dangerous referring to clinically accepted (but not physiology dictated) habits to identify deviations from normal posture.

Several findings are recurrent in healthy posture, what follows is a general (but not comprehensive) guideline based on the author’s self evaluation, population observation and literature review. The guideline lists some conditions observed in physiologic motor performance.

General:

• anatomical, development and motion symmetry;
• motor and static posture reflects individual features, meaning that the same task may be accomplished with different postural expressions by two subjects with different physiology;
• absence of joint degeneration symptoms;
• easiness in learning new complex motor actions;
• good balance during simple and complex motion;
• comfort in every prolonged static weight bearing position, with no need to modify it (eg. upright position, sitting on a chair, sitting on a stool, crouched);

Head:

• teeth physiologic centric occlusion;
• physiologic temporomandibular relationship having condyles symmetrically positioned within each glenoid fossa;
• physiologic craniocervical relationship with small chin/hyoid/tyroid angle and a close to vertical neck inclination;
• loose mandible when heavy breathing during efforts and expressionless facial mimic muscles;

Thorax: wide frontal chest expansion and poor dorsal kyphosis;

Shoulder girdle: shoulder and arms freedom and symmetry of swing during walking and running;

Pelvic girdle:

• tonic gluteus an pelvis posterior tilt in the static uptight position;
• static upright position with hips bearing equal weight;

Pathology

Postural disorder is a sub class of posture, it is exactly defined by the differences between the postural model of an individual with an ongoing pathology and the postural model of the same individual in healthy condition or, with more approximation, by the differences between the postural model of an individual with an ongoing pathology and the average postural model of healty individuals of the same class. Although posture includes reflexive (involuntary) as well as voluntary motor tasks, postural disorder is commonly referred as the disorder of the involuntary motor component only, as disorders of the voluntary motor component are more related to behavioural disorders and are approached differently.

Only after posture physiology definition is agreed it is possible to talk about posture pathology. A diffuse way of thinking is to consider a pathology only a painful symptomatic manifestation, comparing asymptomatic degenerations and asymmetric/disharmonious motion to health, and using overworked slogans like "we all are asymmetric" or "95% of the population has asymptomatic spine degenerations" to motivate the unexplainable. The way physiology "thinks" is different, it considers pathological every motor strategy that provides function in an different way (compensated) from what was originally meant.

Postural distortions always produce a damage, it’s severity and symptoms arising depend on postural impairment harmfulness and individual tolerability threshold. All of this allows to say that these damages are directly related to the initial postural impairment and that their symptomatic manifestation is unpredictable. This "time bomb" feature of postural disorders is it’s worst enemy misleading diagnosis of the initial noxious stimulus, moreover, postural distortions are never perceived by the majority of the population due to slowness in symptoms progression and poor self awareness, making it challenging motivating them a postural diagnosis.

Damages severity and symptoms onset depend on tolerability threshold:

• individual anatomical conformation: on heavy and/or toll persons, tolerability is lower due to joints load;
• individual habits: on athletes, tolerability is lower due to higher anatomy exploiting, a sedentary person may take months to do the amount of strides an athlete takes in a 2h marathon;
• individual background health: in poor health people, tolerability is lower since anabolic functionality (damages self healing) may be compromised by concurrent illness;

and on postural disorder harmfulness:

• pathology mechanics: according to the noxious stimuli, postural system may react with either a low priority light adaptations or high priority violent adaptations
• pathology symmetry: symmetry plays a primary role in harmfulness, markedly asymmetric postural deviations induce highly degenerating unilateral muscular contractions, whereas, perfectly symmetric postural deviations are hardly observable on population;
• pathology chronicity: according to the duration of the postural disorder it’s harmfulness may be acute, chronic or intermittent;

The stages of the postural diagnostic process are:

Pathological process:

• EVIDENCES (clinical, self evaluated, symptoms, others..): collecting every possible detail concerning the patient lamented symptoms, anamnesis, sensations, clinical evaluation findings, that may or may not apparently be related to the postural picture;
• MECHANICS (postural strategy identification): working out the strategy of the postural evidences, requires the careful consideration of all the findings and logical reciprocal relationship, the goal is to determine the pathological postural strategy role of each of them, this is the first of the two main tasks of the postural diagnosis.

The practical example of this multi stage diagnostic approach will appear clearer in the The case study section.

Etiology

The meaning of the word is well known but has to be further tailored to fit the postural requirements, the steps of the ordinary etiological diagnostic process are:

• collecting etiological hypothesis;
• differential diagnosis exclusion (uniqueness of the diagnosis);
• successful etiological therapy outcome (if no irreversible);

Whereas the stages of the postural etiology diagnostic process are:

First primaries process:

• PATHOMECHANICS (pathology identification): every postural deviation has a reason to exist and gives itself reason to exist to other postural compensatory deviations, in order to identify the mechanical cause of the whole postural unbalance one must find the root postural deviation (pathology), the one that is not secondary to any other deviation and that was present before any other (first primary), this is the last of the two main tasks of the postural diagnosis.
• ETIOPATHOGENESIS (etiological diagnosis): this is a matter of diagnostic exploration and loses relation with posturology, taking instead advantage of a more specific approach for the diagnostic process.
• THERAPY (pathology treatment): this is a matter of therapy and loses relation with posturology, taking instead advantage of a more specific approach for maximising therapy outcome, in case of pathology complete regress this is the last step of the process, would it instead cause only a partial regress to the whole postural unbalance (some symptoms persistence) the process must proceed to the next step.

Second primaries process:

• the successful treatment of the primary pathological motor strategy, in cases of chronic postural deviations, may not be sufficient to trigger the complete reversion of all the secondary postural deviations, in this cases the postural deviation have become itself responsible (second primary) to pathologic anatomy development/degeneration that acts now (after first primary cause suppression) as primary cause for the remaining persistent deviations. In this case the etiological diagnosis process (first three steps) has to be repeated for all the second primaries.

The practical example of this multi stage diagnostic approach will appear clearer in the The case study section.

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Posture, etiology of a syndrome - ©2008 Paolo Platania