Postural Assessment. Postural Assessments . Why do we do it? Is it all that important? Can it be changed? . Why do we do it?. Injury prevention? Pain reduction? Aesthetics? Performance? . Posture .
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The importance of normal upright posture has been proposed since the early 1900s when it was described as a state of balance requiring minimal muscular effort to maintain.
Points of reference consisting of the lobe of the ear, the seventh cervical vertebra, the acromial process, the greater trochanter, just anterior to midline of the knee, and slightly anterior to the lateral malleolous which form a theoretical line around which the body is balanced in perfect skeletal alignment, yielding equal weight distribution and maximum joint stability .
Unbalanced biomechanical joint stresses that result from muscle imbalance may lead to joint damage, setting up a vicious cycle of pain and inflammation. The structural inflammation then affects the neuromuscular system of the joint, creating further dysfunction. Eventually the body adapts the motor program for movement to compensate for the dysfunction
Anterior tilt: Lower body cross syndrome A
Posterior Tilt: Lower body cross syndrome B
Postural Structural Biomechanical Model Conclusions
Misalignments can “impose excessive stress on the spine leading to degeneration/damage or dysfunction and eventually to painful back conditions
In this model, the imbalances and symmetries increase the abnormal mechanical/physical stresses imposed on the musculoskeletal system. This may lead recurrent injury or the development chronic conditions through a gradual process of wear-and-tear
NOT SO FAST!
How do these theories hold up?
Is B really caused by A
Is pain and dysfunction really caused by ‘poor posture’
Lets look at this again
Imbalance: tightness with weakness LCS examination
Lumbar lordosis induced by…
These muscle impairments lead to increased lumbar lordosis and might cause chronic low back pain.
Lumbar lordosis and hamstring length
No significant differences in the degree of lumbar lordosis in subjects with and without short hamstrings.
No significant difference in the degree of lumbar lordosis and in the length of hip flexor muscles.
Abdominal length and strength
No association between the angle of pelvic inclination, the size of the lumbar lordosis and abdominal muscle strength
No association between the length of abdominal muscles and the size of lumbar lordosis.
Movement patterns and postural changes
Pain changes movement but does posture change movement patterns?
34,902 Danish twins 20-71 years old
No meaningful differences in frequency in LBP between younger and older individuals, although greater joint degeneration changes are expected in older individuals.
In the biomechanical model the musculoskeletal system is seen as a precision engine where every system, organ and cell works in perfect harmony within itself and other body systems.
All joints and body masses are in some anatomically ideal relation with one another.
Within the biological dimension the structure (spine) is capable of self repair and is able to adapt and change according to needs and demands.
Our structure is within our awareness and highly in tune with our emotions.
The spine can undergo profound physical changes that are well tolerated without the development of a symptomatic condition.
Injury prevention/pain reduction?
Multivariate analysis show that correcting posture may not be the answer to improving LBP
improvements in posture lead to variable increases in shoulder ROM but intensity of pain is not affected. Subjects respond individually to the effects of posture change.
How relevant is postural deviation?
Some support to the belief that reducing the thoracic kyphosis can contribute to improving arm elevation
No studies that have looked at changing kyphosis in people with SIS to determine if it decreases pain.
Leg length discrepancy
Estimated that 90 percent of the population has a leg length inequality with a mean of 5.2mm
Significant if magnitude reaches 20 mm.
No correlation to LBP
Does static posture translate over to dynamic movement?
Posture is structural strength is neural
Increased ROM with postural corrections although this is variable
No significant relationship between lumbar lordosis and isometric strength of the trunk flexors and extensors and hip flexors and extensors.
Abdominal muscle strength not significantly associated with lumbar lordosis.
Can it be changed?
Weak and lengthened agonist vs strong and tight antagonist proposed cause. So what would one do?
Strengthening and stretching exercises have been prescribed according to deviation.
Strengthening = shortening?
Stretching = lengthening?
Does an increase in muscular strength allow a better posture to be held? If this were the case it would not be unreasonable to expect that individuals with poor posture had weak muscles; however this is not the general finding.
Back muscle length was not significantly associated with lumbar lordosis for men or women.
Weakly associated with abdominal length not strength
Exercise programs are insufficient in duration and frequency to induce adaptive changes in muscle-tendon length.
“In the context of postural-structural-biomechanical (PSB) factors, it is expected that tremendous forces, well above the daily physical stresses, would be required to reposition/adjust/correct any structural misalignments. These would have to be applied on a daily basis over several months or even years. A termination of treatment is likely to result in rapid reversal of PSB gains, unless the individual is able to self maintain them by specific exercise. The winner in the competition-in-adaptation, is ultimately the one most practiced, that is, the default PSB state/behavior of the individual”
Incidence of pain increased in subjects with more severe postural abnormalities
However, posture is individual: a number of individuals with normal posture were found to have significant pain, whereas some individuals with more severe postural deviations in the TCS region were found to have minimal pain. Causality cannot be determined.
Age related hyperkyphosis
Impairs mobility and increases risk of falls and fractures.
a kyphosis angle greater than 40 degrees is defined as hyperkyphosis.
Women with hyperkyphotic posture demonstrate difficulty rising from a chair repeatedly without using their arms.
Hyperkyphotic posture has been associated with increased mortality, with higher mortality rates associated with the severity of kyphosis.
Reduced vital capacity is associated with hyperkyphosis, and severe hyperkyphosis is predictive of pulmonary death among community dwelling women.
Women in the highest quartile of kyphosis were more likely to die of pulmonary death compared with those in the lower quartiles of kyphosis.