Influence of pelvic position on shoulder range of motion

doi:10.21203/rs.3.rs-4873762/v1

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Influence of pelvic position on shoulder range of motion

https://doi.org/10.21203/rs.3.rs-4873762/v1

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Background

pelvis and soulder are deeply intergrated. They are connected by myofscial slings. The pelvic and spinal posture affects the position of the scapula and the activity of its muscles and also affects acromio-humeral distance and so that affects shoulder movement. The aim of the study was to investigate the influence of pelvic position on the shoulder range of motion.

Methods

The full active range of motion (flexion/extension, abduction, and external/internal rotation) of both shoulders was measured by digital goniometer for 33 normal adult subjects. Measurements were taken from standing position in the following pelvic positions: 1- Neutral posture, 2- Evoked anterior and posterior pelvic rotation, 3- Evoked right and left pelvic rotation, 4- Evoked right and left lateral pelvic tilt. For every shoulder movement, One Way ANOVA including Tukey post hoc test was used to compare between different positions.

Results

Anterior pelvic tilt leads to significant increase in flexion and significant decrease in extension of both shoulders (P value was < 0.001). Posterior pelvic tilt leads to the opposite. Pelvic rotation leads to significant decrease in shoulder flexion on the same side of rotation and shoulder extension on opposite side of rotation (P value was < 0.001). Lateral pelvic leads to significant decrease of abduction on the same side of lateral tilt (P value was < 0.001).

Conclusion

pelvic position affects shoulder range of motion

pelvis

posture

spine

shoulder

range

motion

The pelvis and shoulder are deeply integrated. Anatomically, the myofascial system connects the pelvis and shoulder. For example, posterior and anterior oblique slings connect the lumbopelvic region to the contralateral shoulder. The gluteus maximus extends into the thoracolumbar fascia through the posterior sling, crosses over to the contralateral latissimus dorsi, and terminates in the contralateral shoulder. The hip-lumbopelvic region is connected to the contralateral shoulder by the anterior oblique sling, which is made up of the hip adductors, transverse abdominis, internal and external oblique, anterior fascia of the trunk, and pectoralis major [1, 2].

Moreover, the shoulder's kinematics can be influenced by these slings' impairment. The contralateral humeral head is positioned incorrectly when there is lumbopelvic dysfunction, this can be caused by altered transmission of the myofascial force from the lumbopelvic region across the oblique sling muscle [3, 4].

In terms of mechanics, walking and mobility heavily depend on the integration of the shoulder and pelvis. Arms swing or counter rotation of the thoracic spine are used as adaptation to pelvic angular momentum [5].

Alterations in pelvic posture can impact posture of the shoulder complex by causing change in spinal posture. The lumbar lordosis is increased by anterior pelvic tilt and decreased by posterior pelvic tilt [6, 7]. So thoracic kyphosis will be changed as a compensation [6]. Reduction in anterior pelvic tilt shifts the body's center of mass posteriorly. As a result, the person reduces their extended trunk posture to maintain the center of mass in the best alignment with respect to the line of gravity in the anteroposterior plane [8].

The scapular position and electromyographic activity of the scapula's muscles during shoulder movement is influenced by the posture of the spine [9]. Scapular elevation results from increased kyphosis of the thoracic spine or from a slouched posture. It reduces the scapula's external, upward, and posterior tilting movements [10, 11, 12]. Scapular protraction and downward rotation can be resulted from bending forward [13]. According to Murta et al. [8], alteration of scapular posture may change the length tension relationship of the scapular muscles, which in turn causes changes in their activity by shoulder movements. The middle and lower trapezius muscle’s activity can be elevated by slouch posture [14].

Additionally, the activation of the scapular muscles is influenced by the pelvic position. Higher activation of lower trapezius during arm movement and a less extended trunk posture are the outcomes of reducing anterior pelvic tilt [8]. To maintain the posture, the gluteus maximus will contract to lessen anterior pelvic tilt, so tightness of the thoracolumbar fascia will occur, causing destabilization of the scapula. As a result, the lower trapezius becomes more active [15]. Additionally, abdominal muscles contribute to the reduction of anterior pelvic tilt and lead to higher activity of the scapular muscles, particularly the lower trapezius [16].

Shoulder mobility is affected by variations in the acromio-humeral distance (AHD), which is caused by changes in spinal position. The AHD is increased by upright position [17]. Conversely, a slouched posture or thoracic hyperkyphosis results in a decrease in the AHD [18]. Thus, assuming a slouched posture reduces shoulder abduction range and strength [10], and assuming an upright posture increases shoulder abduction and flexion range [19, 12].

the anterior scapular tilt and its decreased upward rotation result in decreased abduction and flexion. This is because of blockage created by the acromion and resultant subacromial space narrowing Additionally, the AHD is shortened by scapular protraction [10, 19] Since greater thoracic kyphosis alters the length-tension relationship of the shoulder girdle muscles, the reduced range may be related to the thoracic position itself. Thus, it may result in humeral head malalignment [19, 20].

This study shows the integrated model between shoulder and pelvis and how pelvis affects shoulder range of motion. This model can be beneficial for clinicians in examination and treatment of shoulder patho-mechanics.

This cross-sectional study aimed to investigate the influence of pelvic position on the shoulder range of motion. It was conducted at the faculty of physical therapy, Deraya University.

33 subjects were enrolled in this study. Subject was included in the study if age ranged from 18 to 30 years, BMI ranged from 18 to 24 kg/m², subjects were excluded if they have shoulder, spinal and pelvic pain or disorders, leg length discrepancy, any congenital or acquired deformation.

The full active range of motion of both shoulders was measured in all planes (flexion/extension, abduction, and external/internal rotation). the range was measured by digital goniometer (Baseline 12-1027) from standing position in the following pelvic positions: 1- Neutral or natural posture, 2- Evoked anterior and posterior pelvic rotation. (subject actively made anterior and posterior pelvic rotation), 3- Evoked right and left pelvic rotation (subject stood with one foot in step forward, so that the pelvis was rotated to the opposite direction of the forward foot. i.e., right forward foot led to left pelvic rotation.), 4- Evoked right and left lateral pelvic tilt. (subject stood with one knee slightly flexed, so that the pelvis would laterally tilt to the side of flexed knee)

For flexion and extension measurement, stationary arm of the goniometer was parallel to lateral Medline of the thorax and the movable arm on the lateral midline of the arm. For abduction, stationary arm of the goniometer was parallel to the sternum and the movable arm on the anterior midline of the arm. Concerning external and internal rotation, shoulder was abducted 90 degrees and elbow flexed 90 degrees. Stationary arm of the goniometer was parallel to the ground, axis on the olecranon process and the movable arm on the ulnar border of the forearm.

Sample size was calculated by G^*Power3.1.9.7 with the statistical parameters; effect size f = 0.25, α error probability = 0.05, power (1-β) = 0.80. So, for every shoulder movement, each pelvic position would be represented by 33 observations.

For statistical analysis, Statistical Package for the Social Sciences (SPSS) version 26 was selected to analyze the collected data. For each shoulder movement, One Way ANOVA including Tukey post hoc test was used to compare between different pelvic positions.

33subjects were enrolled in the current study. Their mean value of ages was 23.64 ± 2.32 years, and body mass index (BMI) was 21.65 ± 1.64 Kg/m².

Concerning flexion, there was a statistically significant difference between different pelvic positions as determined by one-way ANOVA. For right shoulder, F (6,224) was 205.8 and P value was < 0.001. for left shoulder, F (6,224) was 236.8 and P value was < 0.001. Compared to the natural pelvic position, by Tukey post hoc test, flexion was significantly increased in anterior pelvic posture (p-value < 0.001), decreased in posterior pelvic tilt (p-value < 0.001) for both shoulders, decreased in right rotated pelvis (p-value < 0.001) for right shoulder and in left rotated pelvis (p-value < 0.001) for left shoulder. On the opposite side, there was no significant difference of flexion in left pelvic rotation for right shoulder and right pelvic rotation for left shoulder, right and left tilted pelvis for both shoulders (table 1).

Also concerning extension there was a statistically significant difference between different pelvic positions as determined by one-way ANOVA. For right shoulder, F (6,224) was 158.9 and P value was < 0.001. for left shoulder, F (6,224) was 154.6 and P value was < 0.001. In comparison to natural pelvic position by Tukey post hoc test, extension was significantly decreased in anterior pelvic posture and increase in posterior pelvic posture for both shoulders, decreased in left pelvic rotation for right shoulder and right pelvic rotation for left shoulder (all P values were < 0.001). On the other hand, there was no significant difference of extension range in right pelvic rotation for right shoulder, left pelvic rotation for left shoulder, right and left tilted pelvis for both shoulders (table 1).

Regarding abduction, one way ANOVA showed significant difference between different pelvic positions. For right shoulder, F (6,224) was 72.17 and P value was < 0.001. for left shoulder, F (6,224) was 127.3 and P value was < 0.001. Compared to the natural pelvic position, Tukey post hoc test showed only a significant decrease of abduction range in right pelvic tilt for right shoulder and left pelvic tilt for left shoulder (P value was < 0.001), while there was no significant difference in all other pelvic positions (table1).

In external rotation, one way ANOVA showed no significant difference between different pelvic positions, for right shoulder, F (6,224) was 1.3 and P value was 0.255. for left shoulder, F (6,224) was 0.45 and P value was 0.844. Also in internal rotation, there was no significant difference between different pelvic positions. For right shoulder, F (6,224) was 0.984 and P value was 0.437. for left shoulder, F (6,224) was 1.006 and P value was 0.423.

Table 1 shows mean values of shoulder range of motion and P value for difference in shoulder range for every pelvic position when compared to natural position by Tukey post hoc test.

Pelvic Position	Flexion				extension				Abduction				External Rotation				Internal Rotation
	Right		Left		Right		Left		Right		Left		Right		Left		Right		Left
	Mean	p-value	Mean	p-value	Mean	p-value	Mean	p-value	Mean	p-value	Mean	p-value	Mean	p-value	Mean	p-value	Mean	p-value	Mean	p-value
Natural pelvic position	175.8		176.66		54.73		54.43		176.40		176.66		88.9		88.23		72.13		72.93
Anterior Pelvic Tilt	180.36	<0.001*	181.56	<0.001*	45.23	<0.001*	46.53	<0.001*	176.86	0.962	176.76	1	89.03	0.999	88.56	0.967	70.83	0.963	70.83	0.678
Posterior Pelvic Tilt	165.36	<0.001*	165.26	<0.001*	62.43	<0.001*	63.53	<0.001*	176.66	0.998	176.56	1	88.53	0.804	88.03	0.998	72.23	1	72.93	1
Right Pelvic Rotation	165.96	<0.001*	178	0.137	56.13	0.349	46.43	<0.001*	176.76	0.989	175.86	0.494	88.6	0.915	88.23	1	70.73	0.947	71.03	.772
Left Pelvic Rotation	176.36	0.951	166.36	<0.001*	46.73	<0.001*	55.53	0.654	175.86	0.928	176.36	0.992	88.5	0.732	88.26	1	72.03	1	71.83	0.980
Right Pelvic Tilt	175.86	1	176.36	0.99	55.43	0.940	55.13	0.943	169	<0.001*	177.9	0.062	88.6	0.915	88.3	1	73.5	0.953	72.63	1
Left Pelvic Tilt	175.76	1	176.66	1	55.33	.971	54.73	.999	177.23	0.6	167.86	<0.001*	88.5	0.732	88.1	1	72.43	1	72.93	1

Table 1: Mean and P value for difference in shoulder range for every pelvic position compared to natural.

P < 0.05= significant *

The aim of this study was to investigate how the pelvic position affects shoulder range of motion. The earlier research examined the connection between the scapula and the thoracic spine, two nearby structures, and the shoulder's range of motion. While some studies focused on the impact of thoracic spine posture on scapular movement [10, 11, 12, 13], others examined the connection between spinal posture and AHD [17, 18]. Moreover, other researches had determined the connection between shoulder range of motion and thoracic spine position [10, 12, 19].

Regarding sagittal movement, flexion and extension, it was found that anterior pelvic tilt would significantly increase flexion of both shoulders and significantly decrease extension of both shoulders. Posterior pelvic tilt would significantly decrease flexion of both shoulders and significantly increase extension of both shoulders. Right pelvic rotation would significantly decrease flexion of right shoulder and significantly decrease extension of left shoulder. While left rotation would significantly decrease flexion of left shoulder and significantly decrease extension of right shoulder. Lateral pelvic tilt (right or left pelvic tilt) didn’t significantly affect shoulder flexion or extension.

The increased flexion with anterior pelvic tilt may be due to anterior translation of body center of mass (associated with anterior pelvic tilt) so that the individual would extend the trunk to maintain the center of mass in good alignment in relation to line of gravity and within the base of stability. This extension or upright posture allows the scapula to take good position and increase the AHD [17] and so that increases flexion. The opposite occurs with posterior pelvic tilt, the center of mass moves posteriorly due to posterior tilt, and the individual would decrease the trunk extension [8]. This decreased extension or slouch posture would decrease upward rotation, posterior tilting, and external rotation of the scapula [10, 11, 12] and decrease the AHD [18] and so that decrease flexion.

The decreased extension of both shoulders with anterior pelvic tilt may be due to increased tension of the anterior myofascial sling during the upright or extended posture. This tension is transmitted from the pelvic area to the contralateral shoulder [3, 4]. while the increased extension with posterior pelvic tilt may be due to decreased tension or relaxation of this sling during less extended or slouch posture.

Pelvic rotation was found to cause significant decrease in shoulder flexion on the same side of rotation and decrease shoulder extension on opposite side of rotation. This change can be justified by alteration in tension of both anterior and posterior oblique slings during pelvic rotation. Also, it can be related to trunk rotation itself as unilateral shoulder movement requires ipsilateral upper thoracic rotation and lateral flexion with extension [21, 22]. Lateral pelvic tilt didn’t significantly affect shoulder flexion or extension, which means that flexion and extension of shoulder is affected by sagittal movement and rotation of the trunk more than frontal trunk movement.

Concerning shoulder abduction, the only significant difference was associated with lateral pelvic tilt. Lateral pelvic tilt would lead to significant decrease of abduction on the same side of lateral tilt. This may be attributed to change in spinal curvature and myofascial tension caused by lateral pelvic tilt.

Regarding external and internal rotation of the shoulder, pelvic position doesn’t significantly affect shoulder rotation. Although the anterior pelvic tilt produced an increase in external rotation of both shoulder and posterior pelvic tilt produced decrease in external rotation, these differences were not statistically significant. Also, anterior pelvic tilt produced a decrease in internal rotation, but also it was not statistically significant. This finding means that shoulder rotation isn’t affected significantly by spinal and pelvic position.

From the previous finding, change of pelvic position has an obvious effect on sagittal shoulder movement (flexion and extension), and to less extent on shoulder abduction with no effect on shoulder rotation (external and internal rotation). The current study pointed out the integrated relationship between the pelvic position and shoulder range of movement. So that, patients with shoulder movement limitation should be examined and treated in integration model including pelvis and spine.

The study was carried out as a trial on evoked position of pelvis, not on real and permanent postures in which soft tissues adaptation and structural accommodation have been occurred. The study was performed from standing, changing the position of measurement such as sitting, or supine may change soft tissue tension and muscles activity and so that affect results. The magnitude of pelvic posture change or tilt wasn’t measured to be statistically related to shoulder range of motion.

Further studies are required to examine shoulder range of motion in permanent abnormal or mechanically impaired pelvic postures, or on opposite way to examine pelvic posture in problematic shoulder.

Pelvic position influences sagittal shoulder movement (flexion and extension), and to less extent shoulder abduction with no effect on shoulder rotation (external and internal rotation).

AHD Acromio-humeral distance

Ethics approval and consent to participate

Ethical approval for the study was obtained from the Faculty of Physical Therapy, Cairo University before beginning of the study (NO: P.T.REC/012/004779). A consent form was assigned by participants before data collection.

Consent for publication

Not applicable.

Availability of data and material

Table 1 contains the datasets necessary for interpretation, any other datasets are available from the corresponding author on reasonable request.

Competing interests

Authors declare no competing interests.

Funding

Not applicable.

Author contributions

BSL was responsible for study design; BSL, MMME, and AK for data collection; all authors for data analysis, interpretation, writing and revision of manuscript; all authors read and approved the final submitted manuscript.

Acknowledgements

The authors would like to thank all participants in the current study.

Authors information

¹ Lecturer of Orthopedic physical therapy, Faculty of Physical Therapy, Deraya University, Minia, Egypt. ² Associate Professor of Biomechanics, Faculty of Physical Therapy, Deraya University, Minia, Egypt. ³ Lecturer of Orthopedic Physical Therapy, Faculty of Physical Therapy, Deraya University, Minia, Egypt.⁴ Department of Physical Therapy, Benha University Hospital, Benha University, Benha, Qalyubia, Egypt. ⁵ Lecturer of Physical Therapy, Basic Science Department, Faculty of Physical Therapy, October University for Modern Sciences and Arts, Giza, Egypt. ⁶ Faculty of Medicine, Sohag University, Sohag, Egypt. ⁷ Lecturer of Physical Therapy, Basic Science Department, Faculty of Physical Therapy, Suez University. Suez-Canal. Egypt.

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No competing interests reported.

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You are reading this latest preprint version

Influence of pelvic position on shoulder range of motion

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Abstract

Background

Methods

Results

Conclusion

Background

Methods

Results

Discussion

Conclusion

Abbreviations

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Status:

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