Examination of posture?

[Guest guest]

One of the members of Somasimple was kind enough to post the below

information from Sahrmann:

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Is the examination of posture just a tradition of physical therapy

practice or is the information gathered from this assessment useful

for diagnosis and treatment? The inclusion of postural assessment in

the Guide to Physical Therapist Practice, the accreditation

standards, and the patient reports of most physical therapists

suggest that the profession considers postural alignment to have a

role in patient care. In keeping with current professional demands,

physical therapy is emphasizing evidence-based practice and outcome

measures. Because criteria for reimbursement and effectiveness of

treatment require outcome information and treatment time is limited,

therapists are minimizing examination of impairments such as posture.

Therapists attempting to meet the demands of efficient practice need

to limit their examination to the impairments that are the most

useful in directing treatment. Though outcome information is

important, it does not direct treatment. Rather, the information

obtained from assessment of impairments should guide the therapist's

diagnosis and treatment plan.12

What is the evidence that postural impairments contribute to pain

problems and need to be included in therapists' examinations? The

simple answer to that question is that there is very little research

to support a relationship between musculoskeletal pain

and ``posture.''10 Many respected texts and articles by

physicians,2,5,9 physical therapists,1,6 and physical educators11,14

have cited the importance of good postural alignment to health, but

clinical studies have not supported these beliefs. Though I am fully

aware of the lack of evidence, I cannot imagine treating any patient

without assessing posture or, more precisely, alignment. When the

patient with low back pain has a flat back, the emphasis of my

treatment is different than when the patient has an excessive lumbar

lordosis. I also expect that the contributing muscle impairments will

be different in these two patients.

Why is there a discrepancy between the research data and the clinical

experience of so many generations of physical therapists? I believe

some of the explanations are (1) a narrow definition of what

constitutes posture;

(2) attempts to find a linear correlation between pain and spinal

curvature without identifying subgroups of extremes of increased or

decreased curvature; (3) failure to consider alignment as only one of

multiple factors causing pain; (4) attempts to relate postural faults

and muscle weakness; and (5) limited research examining the

relationship between alignment impairments and alterations in

movement.

Studies of posture have focused on a narrow definition. Posture or

carriage of the body should be considered differently than the

alignment of one segment in relation to an immediately adjacent

segment. The connotation of posture is the overall relative

disposition of the segments of the body from head to foot, including

the general curvature of the spine. Probably more important than

overall posture in the sagittal plane is the relative alignment of

one or two segments in multiple planes. For example, the degree of

lumbar curvature can vary a great deal, but one vertebra cannot

change its sagittal position with another vertebra by more than a

couple of millimeters before contributing to pain from

spondylolisthesis.

Paraspinal asymmetries indicative of only a few degrees of rotation

between 2 vertebrae can be more problematic than several degrees of

an increased curve involving 5 vertebrae. The study by Norton et al,8

published in this issue of JOSPT, demonstrates that the calculation

of lumbar curvature varies with the instrumentation and the formula

used for calculation. Sensitive measurement tools, capable of

detecting significant variations in alignment of a segment or two

from the normal range, are going to be necessary to assess the

relationship of alignment to pain. Imaging systems, such as the one

used in the study by Lentell et al,7 also published in this issue of

JOSPT, are currently necessary for this task; but the possibility

exists that noninvasive, less expensive measurement systems could

detect risk factors before they result in pain. Studies have not

addressed whether some postures are more likely to result in

intersegmental changes such as spondylolisthesis than other postures.

Until a few years ago, medical practitioners would have been unable

to correlate obesity in children and the presence of diabetes. But

now the relationship between bodyweight and type II diabetes is

clear, so weight can be considered a risk factor. Furthermore, we

also know that fat distribution over the abdomen is a greater risk

factor for diabetes than fat distribution over the hips and thighs.

But, even with diabetes, a linear correlation between bodyweight and

the severity of the disease has not been demonstrated.

Similarly, we cannot expect a linear correlation between spinal

curvature and severity of back pain because too many other factors

affect the condition. We need to avoid generalizing the negative

results of studies of overall posture or even of spinal curves and

propose other more incisive questions before assuming that alignment

is not important.

Defining subgroups of extreme postures is a necessary step in the

consideration of alignment as a contributor to mechanical pain

problems. Establishing normative values with standard deviations for

spinal curvature would be useful in analyzing the effects of extreme

variations of spinal alignment on the development of pain problems.

To use alignment as a guide to or an indicator of mechanical pain

would require that the degree of deviation is sufficient to be

defined as a risk factor. Scoliosis is a good example of a condition

in which the degree of malalignment is important. A few degrees of

scoliosis does not require intervention, but once the curve reaches a

critical angle, surgical intervention is recommended. Physiological

measures used by physicians have wide standard deviations that can be

considered within the normal range. Blood pressure can vary from

70/40 to 130/90 and still be considered within the normal range.

Similarly, measures of heart rate and cholesterol levels have wide

ranges before they are considered abnormal. Extremes in alignment,

such as the flat back versus the severely lordotic back, could both

be greater risk factors for pain than the presence of a lumbar curve

in the normal range.

Classifications of patients such as those who have pain with lumbar

flexion versus those whose pain occurs with lumbar extension may be

guided in part by spinal alignment. We also know that patients with

spinal stenosis have pain with the small

increase in the lumbar curve that occurs in standing and usually

cannot be classified as having a lumbar lordosis. Thus, back

alignment cannot be expected to correlate with all causes of pain

even when pain is elicited in a common movement direction.

Alignment is only one of multiple factors contributing to the

development of mechanical pain. Other demographic information can

also influence whether the measure of lumbar curvature is important.

Age, sex, weight, and activity are variables that influence the

interpretation of physiological measures and certainly, they can also

influence the interpretation of alignment and kinesiological

measurements. For example, an individual with an increased lumbar

curve who sits most of the day may not have back pain. But if another

individual with the same excessive lumbar lordosis has a job that

requires standing all day, he or she is probably more likely to

develop back pain. The individual who is overweight with a ponderous

abdomen who stands all day may be at greater risk of developing back

pain than an individual who is slender with the same alignment who

also stands for prolonged periods. I believe most clinicians who use

postural alignment as a guide to their diagnosis and treatment have

consciously or subconsciously defined for themselves the degree of

deviation, the context, and the modifiers that when combined reach a

level of perceived clinical significance.

Studies suggesting that posture was not correlated to muscle strength

also raised doubts about the value of alignment impairments because

of the lack of valid information about muscle function.4,13 However,

studies of muscle mutability suggest that adaptations of muscle other

than ``weakness'' could underlie variations in posture. The classic

study of andGoldspink15 demonstrated that sarcomeres are

added and lost in series, which affects muscle length. This finding

raises the possibility that a postural fault such as an excessive

anterior pelvic tilt can be the result of increased muscle length and

not decreased muscle strength. Other studies have demonstrated that

the passive tension of muscle has a high correlation with muscle

volume.3 Thus anterior pelvic tilt could also be the result of

hypertrophy of the back extensor and hip flexor muscles, which in

combination create a greater passive tension for anterior pelvic tilt

than the passive tension created by the abdominals for posterior

pelvic tilt.

A variety of combinations of muscle length and passive tension can be

proposed to explain postural alignments. To develop an effective

treatment program, the therapist should determine the combination of

these impairments that is producing the alignment fault and

the association with the pain problem. Therefore, negating the value

of postural assessment because muscle weakness is not always a factor

is overlooking other possible biological explanations involving

muscle mutability that may have even greater implications for

treatment.

The and Goldspink15 study also demonstrated that the

addition of sarcomeres in series shifts the active length-tension

curve of muscle to the right. The consequence is that elongated

muscle would not move a segment through the same range of movement as

a shorter muscle would. Thus a patient with a markedly downwardly

rotated and adducted scapula, indicative of a long serratus anterior

muscle, would not achieve 40° of upward rotation

and adequate abduction of the scapula when performing 180° of

shoulder flexion. A reasonable assumption is that biomechanical

systems are similar to mechanical systems; thus, optimal alignment is

the desirable if not the necessary requirement for optimal movement.

The static position is indicative of the effect on the moving parts

as well as on the precision of motion. The misalignments of the foot

are good examples. Arch supports are often recommended for the

pronated foot because the abnormal distribution of forces during

walking can result in foot pain. Similarly at the shoulder, when the

humerus is aligned in medial rotation and the lateral rotators do not

correct the starting position during shoulder flexion, the greater

tuberosity of the humerus can impinge on the acromion.

Physicians use outcome assessments of changes in pain and

performance, but their surgical and pharmaceutical treatments are

directed toward correcting the pathophysiological problems causing

the pain. The findings from physiological measurements direct

treatment. So too must physical therapists use biomechanical measures

of impairments to direct treatment.

Alignment as a critical component of movement must be one of the

impairments that are assessed. In my judgment, the current

preponderance of negative studies about the relationship between

posture and pain are more reflective of the types of questions that

have been asked and the analysis that has been used than of the lack

of a relationship. Assessment of alignment impairments has to be an

important step in designing an appropriate treatment program for

correcting mechanical impairments. We need to pursue the studies that

will enable us to define the relationships among specific alignment

impairments, altered movement patterns, contributing muscle

adaptations, patient modifiers, a d mechanical pain problems.

References

1. Bullock-Saxton J. Normal and abnormal postures in the sagittal

plane and their relationship to low

back pain. Physiother Prac. 1988;4:94–104.

2. Cailliet R. Low Back Pain Syndrome. 3rd ed. Philadelphia, PA: FA

; 1981:58–63.

3. Chleboun G, Howell JN, Conatser RR, Giesey JJ. The relationship

between elbow flexor volume and

angular stiffness at the elbow. Clin Biomech. 1997;12:383.

4. Diveta J, M, Skibinski B. Relationship between performance

of selected scapular muscles and

scapular abduction in standing subjects. Phys Ther. 1990;70:470–476.

5. Hellebrandt FA, Franseen EB. Physiological study of the vertical

stance of man. Physiol Rev.

1943;23:220–249.

6. Kendall FP. Muscles, Testing, and Function. 4th ed. Baltimore, MD:

Lippincott, & Wilkins;

1993.

7. Lentell G, Kruse M, Chock B, K, Iwamoto M, R.

Dimensions of the cervical neural

foramina in resting and retracted positions using magnetic resonance

imaging. J Orthop Sports Phys

Ther. 2002;32:380–390.

8. Norton BJ, Hensler K, Zou D. Comparisons among noninvasive methods

for measuring lumbar

curvature in standing. J Orthop Sports Phys Ther. 2002:32:405–414.9.

Pope MH, Bevins T, Wilder DG, Frymoyer JW. The relationship between

anthropometric, postural,

muscular, and mobility characteristics of males ages 18–55. Spine.

1985;10:644–648.

10. Raine S, Twomey LT. Attributes and qualities of human posture and

their relationship to dysfunction

or musculoskeletal pain. Crit Rev Phys Rehabil Med. 1994;6:409–437.

11. Rasch PJ, Burke RK. Kinesiology and Applied Anatomy. 6th ed.

Philadelphia, PA: Lea and Febiger;

1978:361–387.

12. Sahrmann SA. Diagnosis and Treatment of Movement Impairment

Syndromes. St. Louis, MO: Mosby,

Inc; 2001.

13. ML, Rothstein JM, Finucane SD, Lamb RL. Relationships

between lumbar lordosis, pelvic tilt,

and abdominal muscle performance. Phys Ther. 1987;67:512–516.

14. Wells KF. Kinesiology: The Scientific Basis of Human Motion. 5th

ed. Philadelphia, PA: WB Saunders

Co; 1971:370–385.

15. P, Goldspink G. Changes in sarcomere length and

physiological properties in immobilized

muscle. J Anat. 1978;127:459–468.

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Carruthers

Wakefield, UK