Spinal and shoulder complex posture. II: thoracic alignment and shoulder complex position in normal

Spinal

and shoulder

_complex

_posture.

II:

thoracic

alignment

and shoulder

_{complex position}

in normal

and

_osteoporotic

women

Elsie Culham and Malcolm Peat School of Rehabilitation Therapy, Queen’s _{University, Kingston,} Ontario

Address for _{correspondence:} Elsie Culham, School of Rehabilitation Therapy, Louise D Acton _Building, Queen’s University, Kingston, Ontario K7L 3N6, Canada.

Thoracic

_spine

and shoulder

_complex

_posture were measured in 57 women over

the age of 50. On the basis of thoracic _spine measures, the women were divided into normal _posture (n = 27), thoracic kyphosis (n = 18) and thoracolumbar

kyphosis (n = _{12) posture}

groups. Analysis of variance was used to determine if

shoulder _{complex postural} measures _{differed in the three groups. In} the

_sagittal

plane, both abnormal _{posture groups} had

_{significantly}

_greater forward _angulation

of the scapula and humeral extension _compared with the normal posture group. In the transverse _{plane, scapular protraction} and the _angle between the _scapular

spine

and clavicle were

_{significantly}

_greater in the thoracic

_kyphosis

_group

compared with the other two _{groups. In} the coronal

_plane,

the abduction _angle of

the humerus was _{significantly} less in the thoracic _kyphosis group compared with the normal _{posture group. No difference} was found in _{scapular position} in this

plane. Although

differences were _apparent between the posture groups, many

of the clinical

_{hypotheses regarding}

the effect of _{spinal posture} on shoulder complex position were not substantiated _by the results of this _study.

Introduction

It is

_{generally recognized}

that abnormal

_sagittal

plane alignment

of the cervical and thoracic

spine

can contribute to

_pain

and

_dysfunction

in the neck and shoulder

_region.l-6

Specifi-cally,

several authors have

_suggested

that an

exaggerated

thoracic

_kyphosis

alters the

_resting

position

of the shouldered

_{complex resulting}

in

a forward- or round-shoulder

posture.2,6,7

The

scapula

is described as

_following

the contour of the thorax and is said to shift

_{anterolaterally}

or

to assume a more

_{protracted position}

in

_subjects

with increased thoracic

_kyphosis.

In

addition,

the

scapula

is

_thought

to rotate such that the

_glenoid

cavity

has an increased downward inclination.6-8 Kessler and

_Hertling7

stated that the

_freely

hang-ing

humerus assumes a more abducted

_position

relative to the

_scapula

and that tension is lost in the

inter-nally

rotated

_position

of the arms is said to occur

due to the

_protracted

_position

of the

_scapula.9

The consequences of the altered

position

are

postulated

to include

_lengthening

or

_shortening

of

_muscle,

muscle weakness and

_changes

in the direction of muscle

_pull

as well as limitation of

upper

extremity

range of motion.2,3 Rehabilita-tion efforts are often aimed at restoration of the

’normal’

_position

and function

by

stretching

struc-tures assumed to be contracted and

strengthen-ing

musculature assumed weak due to

_prolonged

stretch.l°

However,

despite

the various clinical observations

_regarding

the detrimental effects of abnormal

_spinal

_posture

on shoulder

_complex

position,

no studies could be found in which the

claims were substantiated

_{by objective}

measure-ment.

The purpose of this part of the

study

was to determine

_if,

and to what _extent, shoulder

com-plex position

was affected

_{by alignment}

of the

thoracic

_spine

in the

_{sagittal plane.}

An older

female

_population

was chosen for

_study

as

pre-vious research has demonstrated that

_postural

changes

are _age related and are

_greater

in females

than males.11,12 In

_addition,

the incidence of

spi-nal

_{osteoporosis,}

which is known to affect

_sagittal

plane spinal alignment,

is

_higher

in women. 13~--15

Methodology

A detailed

_description

of the

_technique

used to

measure

_spinal

and shoulder

_complex

_posture is

found in _part I*

_{(Figure 1).}

Since the linear

meas-ures of

_{scapular position}

were

_compared

across

subjects

in this

_part

of the

_study

it was

neces-sary to normalize these measures to account for differences in

_subject

size. Both measures

(Yabs

and

_Zabs)

were normalized

_by

_{dividing by}

the

length

of the clavicle

_{(three-dimensional}

distance

between the landmarks on the medial and lateral ends of the

_clavicle).

The

_resulting

measures were

labelled Ynor and Znor

_{respectively.}

*

Clinical Rehabilitation _1993; 7: 309-18.

Figure 1 _Angular measures of shoulder complex position.

(A) Sagittal plane. ScSg, forward _angulation of the medial border of the _{scapula; HSg,} flexion _angle of the humerus

relative to the vertical.

(B) Coronal _plane. ScCo, abduction _angle of the _scapula; CICo, elevation of the clavicle from medial to lateral; HCo. abduction _angle of the humerus.

(C) Transverse plane. ScTr, protraction angle of the scapula; CITR, retraction angle of the clavicle; HTr, internal rotation angle of the _humerus.

Subjects

Thoracic

_posture

and shoulder

_{complex position}

were measured in a total of 57 women between

the _{ages of} 50 and 85 years.

Thirty-six

of the

sub-jects

were recruited from the

_community.

Two of

these

_subjects

were

_being

treated for

_{osteoporosis.}

Twenty-one

women with a

_diagnosis

of osteopor-osis were recruited from an

_outpatient

metabolic

clinic of a local

hospital.

Fifteen of these

subjects

had

_radiographic

evidence of vertebral fracture at at least one

_spinal

level. Exclusion criteria

included presence of a cardiac

pacemaker,

his-tory

of

_neurological

disorder,

history

of surgery

involving

the

_spine

and shoulder

_complex

and a

significant

scoliosis of the

_{spine. Subjects}

had to be

_medically

stable and be able to assume and maintain a

_standing

_position

for a minimum of 10

minutes without discomfort. The

_procedure

was

explained

to the

_subjects

_{and all gave informed} consent

_prior

to their

_{participation}

in the

_study.

Postural

_subgroups

Subjects

were classified into one of three

postural

groups on the basis of the values obtained for thoracic

_kyphosis

and _upper

tho-racic

_slope

_{(Figure 2).}

The _groups

_resulting

from this classification were:

1)

Thoracic

_kyphosis:

18

_subjects

had a thoracic

kyphosis

value of

_greater

than 42

_degrees,

higher

than any of the values found in normal

young women in a

_{pilot study.}

These

individ-uals were

_placed

in the thoracic

_kyphosis

pos-ture _group.

2)

Thoracolumbar

_kyphosis:

_{this group included}

subjects

in whom the location of the

_kyphotic

curvature was

_low,

at the thoracolumbar

junc-tion or in the lumbar

_region.

Criteria for

inclusion in this _group included an _upper

thoracic

_slope

of

_greater

than or

_equal

to 20

_degrees

and a

_kyphosis

value of less than

35

_degrees.

Thoracolumbar

_kyphosis

was

evi-dent in the

_osteoporotic

_subjects

whose frac-tures

_primarily

involved the lower thoracic or

lumbar

_vertebrae,

but was also seen in

sev-eral of the women recruited from the

com-munity.

Twelve

_subjects

met the criteria for thoracolumbar

_kyphosis

and were included in

this _group.

3)

Normal _posture: thoracic

_posture

was

consid-ered to be normal in the

_remaining

27

_subjects

who were

_{subsequently placed}

in the normal

posture group.

The two abnormal _posture groups are similar to the ’hollow round back’ and ’lower acute

_kyphosis’

postures described

_by

Itoil6 for women with

_spinal

osteoporosis.

Descriptive

statistics for _age,

_height

and

_weight

of the

_subjects

in the three

_postural

groups are found in Table 1.

Figure 2 Classification of _{spinal posture} into three groups

on the basis of values obtained for thoracic kyphosis and

upper thoracic slope

Statistical

_analysis

’ ..

The mean values of age,

height

and mass as

well as means of the

spinal

and shoulder

com-plex

measures were

_compared

across the three

postural

groups

using

a _one-way

_analysis

of

vari-ance

(ANOVA).

In the case of a

significant

F-ratio

a _post hoc Scheffe test was

_completed

to determine

where the differences were. A level

_{of p}

< 0.05

was chosen as the maximum level for statistical

sig-nificance for all ANOVA

_analyses.

_Systat

_(Systat

Inc., Evanston,

IL)

statistical software was used

for all

_analyses.

Results

Posture

_subgroups

Although

the mean _age was _greater and the mean mass less in the thoracic

_kyphosis

_{group than}

in the other two

_postural

_groups the differences

were not

_{statistically significant.}

_Similarly,

there

were no

_significant

differences in mean

_height

among the three

postural subgroups

(p

>

0.05).

The

_spinal

_posture

measures and results of sta-tistical

_analyses

are

_presented

in Table 2. The mean

kyphosis angle

was much

_greater

in the

thoracic

_kyphosis

_{group than} in the other two

postural

groups

(F

=

_38.46;

p <

_0.001).

_Upper

thoracic

_slope

was

_greatest

in the thoracic

kypho-sis _group followed

_by

the thoracolumbar

_kyphosis

group. The mean was

_{significantly}

different for all

comparisons.

The lower thoracic

_slope

was

great-est in the thoracic

_kyphosis

_group and lowest in the thoracolumbar

_kyphosis

_{group. The}

differ-ence between _groups was

significant (F

=

_16.20;

p <

_0.001).

Post hoc

_analyses

revealed that the difference was

significant

for all

_comparisons.

Shoulder

_complex

_position

Sagittal plane

Results of

_analyses

of

_{sagittal plane}

measures are

_presented

in Table 3. The medial border of the

scapula

was

_angled

forward 12.24

_degrees

on

aver-age in the normal

posture

group. This

angle

was

significantly

greater, 18.93 and 17.88

_degrees

in the thoracolumbar and thoracic

_kyphosis

_groups,

respectively.

The relative

_angle

_{between the upper} thoracic

_spine

and the medial border of the

_scapula

(ScSgR)

was

_{significantly}

increased in the

tho-racic

_kyphosis

_group

_compared

with the other two

_postural

_groups.

The humerus was flexed a mean of 1.85

_degrees

from the vertical in the normal

_posture

_group. This

compared

with a mean

_angle

of 5

_degrees

exten-sion in both the abnormal

_posture

_{groups. There}

was no difference in the humeral

_angle

relative to the medial border of the

_scapula

_{among the three} groups

(p

>

_0.05).

Transverse

_plane

Results of

_analyses

of transverse

_plane

Table 2 Thoracic spine measures in postural groups

All values in _degrees.

SD = _{standard deviation; UTS} =

slope of the upper thoracic _spine measured from T1 downward; LTS = _slope of the lower

thoracic spine measured from T12 upward; K = thoracic

measures are

presented

in Table 4. The mean

retraction

_angle

of the clavicle

_(CITr)

was 23.87

degrees

in the normal

_posture

_{group. This} was

not

_{significantly}

different from a mean of 21.57

and 24.01

_degrees

in the thoracolumbar and

tho-racic

_kyphosis

_group

_{respectively.}

The

_protraction

angle

of the

_{scapula (ScTr)}

and the relative

_angle

between the

_spine

of the

_scapula

and clavicle

(CITrR)

were

_{significantly}

_greater

in the group

with thoracic

_{kyphosis compared}

with the other groups.

The humeral

_angle

in the transverse

_plane

was

the most variable of all the shoulder

_complex

measures as indicated

by

the standard deviations.

This

_angle

was less in the thoracic

kyphosis

_group,

compared

to the other two _groups, but the

dif-ference was not

_{statistically significant.}

Humeral rotation relative to the

_spine

of the

_scapula

was

lower in the thoracic

_kyphosis

_group and

_higher

in the thoracolumbar

_kyphosis

_group

_compared

with the normal

_posture

_group. The difference between

the two abnormal _{posture groups} was

_significant.

Coronal plane

Results of

_analyses

of coronal

_plane

measures

are

_presented

in Table 5. The

_angle

of the medial

border of the

_scapula

to the horizontal was 92.14

degrees

in the normal _{posture group. This}

_angle

was lower in the two abnormal _{posture groups but} the difference was not

_significant

_(p

<

_0.05).

The

_angle

of elevation of the clavicle from

medial to lateral was 7.13

_degrees

in the

nor-mal _{posture group. This}

_angle

was increased in

both abnormal

_posture

_{groups with the greatest}

difference

_occurring

between the normal and thoracolumbar

_kyphosis

_groups.

The humeral abduction

_angle

was less in both abnormal

_postural

_groups

_compared

with the

nor-mal _group. Post hoc

_analysis

revealed that the

dif-ference was

_significant

_only

between the thoracic

kyphosis

and normal group. The abduction

_angle

of the humerus relative to the

_scapula

_(HCoR)

was

lowest for the thoracic

_kyphosis

_group.

However,

the difference among groups was not

_{statistically}

significant.

Linear measures

Results of

_analysis

of the linear measures are

presented

in Table 6. The normalized linear

dis-tance from Tl to the

_scapular

centre

_along

_{the y}

(Ynor)

and z

(Znor)

axes were not

_{significantly}

different in the

_postural

_groups.

Table 3 _{Sagittal plane} shoulder complex measures in _{postural groups}

All values in degrees.

SD = standard _deviation; ScSg =

angle of forward tilt of the medial border of the scapula to the _{vertical; ScSgR =} relative angle between the medial border of the scapula and the upper thoracic spine derived _{by subtracting ScSg} from UTS;

HSg = angle of the long axis of the humerus to the vertical, a _positive value _indicating flexion; _HSgR = _angle of the humerus

Table 4 Transverse plane shoulder complex measures in _{postural groups}

All values in _degrees.

SD = _{standard deviation;} ScTr = the protraction angle of the scapular spine relative to a coronal axis defined by a line connecting the roots of the right and left scapular spines; CITr = the retraction _angle of the clavicle relative _to the coronal

axis as defined above; CITrR = the angle between the clavicle and the spine of the scapula in the transverse plane;

HTr = the _angle of internal rotation of the humerus; HTrR = internal rotation angle of the humerus relative _to the _spine of the

scapula.

Table 5 Coronal plane shoulder complex measures in _postural groups

All values in _degrees.

SD = _{standard deviation;} ScCo = _scapular abduction angle measured _as the lateral angle formed between the medial border

of the scapula and the horizontal; CICo = _{the medial to lateral angle} of elevation of the _{clavicle; HCo} = _{the abduction angle}

of the humerus relative to the vertical; HCoR = _{the abduction angle of the humerus relative to the medial border of the}

Table 6 Linear shoulder complex measures in postural groups

All values in cm.

SD = standard deviation; YNor = _{the linear distance in centimetres from T1 to the centre of the three scapular landmarks}

along the y axis, normalized _{by dividing by} the _length of the clavicle; ZNor = _{linear distance from T1 to the centre of the}

three _scapular landmarks, normalized by dividing by the length of the clavicle. Discussion

It has been

_hypothesized

that

_changes

in

_sagittal

plane

posture,

specifically

thoracic

_kyphosis

and forward-head

_posture,

result in

_changes

in the

resting position

of the shoulder

_complex.

The

results of this

_study

indicate that an increase in

anteroposterior

curvature of the

_{spine, regardless}

of the level at which it occurs, causes an increase

in _upper thoracic

_slope

which could contribute to a forward head

_position.

However,

it is also

evident from the results that the

_position

of the

skeletal

_components

of the shoulder

_complex

was

dependent

on the location of the curve.

It is not

_surprising

that

_changes

in

_{sagittal plane}

spinal

posture

affected the

_{sagittal plane}

shoulder

complex

position

measures,

although

no clinical

reports

regarding

the effect of

_{postural changes}

on

the shoulder

_{complex position}

in this

_plane

have

been found. Forward

_angulation

of the medial border of the

_scapula

was

_greater

in both of the

abnormal _{posture groups}

_compared

with the

nor-mal

_posture

_group.

However,

the relative

_angle

between the medial border of the

_scapula

and

the upper thoracic

_spine

was increased

_only

in

the

_subjects

with an increase in thoracic

kypho-sis

_angle.

These

_findings

can be

_explained

_by

the

location of the

_kyphotic

curve and the

_resulting

effect on the

_shape

of the thorax. In

_subjects

with a thoracolumbar curve the

scapula angled

forward

to

_{approximately}

the same

_degree

as the

upper thorax and the relative

angle

between the upper thoracic

spine

and medial border of the

scapula

(ScSgR)

was not

_{significantly}

altered.

When the curvature is in the thoracic

_region

the ribs become

_{prominent dorsally}

and the

anteroposterior

diameter of the thorax appears to be increased. The

_prominent

dorsal ribs _may

prevent the

_scapula

from

_tilting

forward to the

same

_degree

as the _upper thoracic

_spine

result-ing

in the marked increase in the relative

_angle

between the upper thoracic

spine

and

_scapular

medial border

_(ScSgR)

in these individuals. This

could

_potentially

result in a

_{gradual elongation}

of structures

_having

attachment to both the cervical

spine

and the

_scapula.

For

_example,

this abnormal

posture

may lead to

_pain

and irritation at the site

of insertion of the levator

_scapula

as described

_by

Cailliet.s The fibres of the _upper

_trapezius

and

rhomboid muscles and the

_{suprascapular}

nerve

might

be

_similarly

affected.

The humerus was in more extension in both

the abnormal

_posture

_groups

_compared

with the

normal group, but there was no

_significant

dif-ference in the

_angle

of the humerus relative to the

_scapula

_(HSgR)

in this

_plane.

This indicates

that the humerus moved with the

_scapula

or the

humerus extended as the forward

_angulation

of the

_scapula

increased. Both abnormal

_postures

resulted in an increase in _upper thoracic

_slope.

Extension of the arms _{may be} a _compensatory

movement to

_help

offset the anterior

_displacement

of the upper thorax and maintain balance.

The

_{protraction angle}

of the

_{scapula (ScTr)}

in

the transverse

_plane

was

_{significantly}

_greater

in

thoracic

_spine.

This

_finding

can also be

_explained

by

the increased

_prominence

of the ribs

_dorsally

and the increased

_{anteroposterior}

diameter of the thorax evident in

_subjects

with a mid-thoracic

curves The

_angulation

of the

_scapula

and/or the clavicle must increase to accommodate the

_greater

anteroposterior

thoracic diameter. The results are

in

_agreement

with the clinical literature

describ-ing

increased

_{scapular protraction}

with thoracic

kyphosis.7,9,17

The relative

_angle

between the

scapular spine

and clavicle

_(CITrR)

was also

greatest

in

_subjects

with thoracic

_{kyphosis again}

suggesting

an accommodation to an increased

anteroposterior

diameter of the thorax.

The results of this

_study

_suggest

that

_protracted

scapulae

or ’round shoulder

_posture’

does not

necessarily

accompany a forward head

_position

as

_suggested

in the literature. 7.9,17

_Subjects

in

both the thoracolumbar and thoracic

_kyphosis

posture

groups had an increase in _{upper thoracic}

slope

and a

_clinically

_apparent

forward head

pos-ition

_compared

with the normal

_posture

_subjects.

However,

subjects

with a thoracolumbar

_kyphosis

did not have

_{protracted scapulae.}

The

_position

of the

_scapula

in the transverse

_plane

_appears to be affected more

_by

the

_{anteroposterior depth}

of

the thorax than

_{by sagittal plane}

_posture of the

spine.

It _{would appear,}

_therefore,

to be incorrect to

_equate

a

_particular

shoulder

_{complex position}

with a forward head _posture.

The relative

_angle

between the humerus and

scapula

in the transverse

_{plane (HTrR)}

was less

in the thoracic

_kyphosis

_group

_compared

with the

other two

_posture

_groups,

_indicating

external rota-tion of the humerus relative to the

_scapula.

This

finding

does not

_support

the

_concept

of

increas-ing

internal rotation of the humerus as

kyphosis

increases. The relative external rotation of the

humerus may be

compensatory

to

_protraction

of the

_scapula

in order to maintain an _upper

extrem-ity position

more conducive to function.

The

_angle

of the

_scapula

in the coronal

_plane

was

less in the two abnormal _{posture groups}

_compared

with the normal _{posture group,}

_indicating

a

ten-dency

towards

_scapular

adduction.

_However,

the differences in the mean

_angles

were small and

not

_{statistically}

_significant.

_Thus,

there is little evidence from this

_study

to _{indicate that} scapu-lar adduction

_(downward

rotation of the

_glenoid)

accompanies

an increase in thoracic curvature

as

_{proposed by previous}

authors.7,9 Downward

scapular

rotation as a cause of

_elongation

of

leva-tor

_scapula

and irritation at its site of insertion

proposed by

Cailliet5 also appears doubtful based

on these

_findings.

The mean elevation

_angle

of the clavicle was greater in both the abnormal

_posture

_groups.

Subjects

in both of these _{groups had} an increase

in _upper thoracic

_slope.

As this

_slope

increases the sternum and medial end of the clavicle would

tend to become

_{depressed possibly resulting}

in the

observed increase in the

_angle

of elevation from medial to lateral in the abnormal

_posture

_groups.

The humerus was less abducted in the thoracic

kyphosis

group

compared

with the other two groups. The abduction

angle

of the humerus to the

_scapula

_(HCoR)

was also less in this group

though

the difference was not

statisti-cally

significant.

Thus,

there was no evidence

from this

_study

to

_support

the

_hypothesis

that the humerus abducts relative to the

_downwardly

rotated

_scapula

in

_subjects

with

_kyphotic

_posture

as

_proposed

_by

Kessler and

_Hertling.7

The trend

would appear to be the reverse with adduction of the humerus relative to the

_{scapula occurring}

in

subjects

with

_increasing

thoracic

_kyphosis.

The linear distance from Tl to the

_scapular

centre was not

_{significantly}

different in the three

postural

groups. There is no evidence from this

study,

therefore,

to

_support

the

_theory

that the

scapula

moves

_laterally

on the chest wall in

subjects

with

_{kyphosis leading}

to

_elongation

of the rhomboid and middle and lower

tra-pezius

muscies.4,10 The ’stretch-weakness’ of the

middle and lower

_trapezius

muscle in _{persons with}

’kyphosis

and forward shoulders’ as

_{proposed by}

Kendall and

_McCreary’O

_{and, thus,}

the need for

strengthening

of the

_scapular

retractors _in

per-sons with

_kyphosis

should be

_questioned

in

_light

of these

_findings.

Although

mean values of Znor indicated that

the

_scapula

was

_depressed

on the thorax in the thoracic

_{kyphosis subjects}

and elevated in the

thoracolumbar group

compared

with the normals

this difference was not

_{statistically}

_significant.

Conclusions

The

_{resting position}

of the shoulder

_complex

was

altered in the abnormal

_posture

_groups

thoracic _posture. The shoulder

_complex

posi-tion was

_dependent

on where the curve was

located;

thoracic versus thoracolumbar

region.

The effect of _posture on the

_{resting position}

of the shoulder

_complex

_{may be} related more to the

resulting changes

in the

_shape

_{of the thoracic cage} rather than to the

_{sagittal plane}

curvature alone.

References

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