Association of Both Scapular Upward Rotation and Scapulothoracic Muscle Lengths With Shoulder Pain, Function, and Range of Movement

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Abstract

Objective

Our aim was to analyze whether shoulder pain is related to scapular upward rotation (SUR) or to the lengths of the pectoralis minor and levator scapulae muscles.

Methods

This cross-sectional, observational study was carried out in 3 primary-care centers; 54 individuals with chronic shoulder pain participated. Scapular upward rotation and the lengths of the pectoralis minor and levator scapulae muscles were assessed.

Results

The level of association was small between shoulder pain and function and (1) the lengths of the pectoralis minor (r = 0.08, P = .93) and levator scapulae (r = −0.01, P = .57) muscles and (2) SUR at 45° (r = 0.17, P = .21), 90° (r = 0.08, P = .57), and 135° (r = 0.10, P = 0.45) of shoulder elevation.

Conclusion

The relationship was small between shoulder pain and function and (1) SUR (45°, 90°, and 135° of shoulder elevation) and (2) the lengths of the pectoralis minor and levator scapulae muscles. Thus, the use of SUR and pectoralis minor and levator scapulae lengths in shoulder assessment should be undertaken with caution. Other factors such as psychological factors, central/peripheral sensitization, and intrinsic properties of the tissue have to be taken into account.

Introduction

Shoulder pain is one of the most common musculoskeletal conditions, with subacromial pain syndrome (SAPS) being the most frequent presentation.1,2 The prevalence of shoulder pain increases with age,3 is greater in women,4 and reaches a point prevalence from 6.9% to 26%, 18.6% to 31% for 1-month prevalence, 4.7% to 46.7% for 1-year prevalence, and 6.7% to 66.7% for lifetime prevalence.5

Both intrinsic and extrinsic factors have been proposed as possible causal mechanisms of shoulder pain, of either isolated or mixed etiology.6, 7, 8 Alterations in scapular biomechanics have often been linked with SAPS,9, 10, 11, 12 and its most common causative mechanisms, such as inflexibility (tightness) and alterations in the periscapular muscles, normally involve the soft tissue.13 In this respect, both a shortened pectoralis minor14 and levator scapulae15, 16 have been related to altered scapular positioning. Additionally, pectoralis minor length and its shortening have been studied in association with shoulder external rotation17 and as an outcome measure after a stretching program in individuals with shoulder pain.18

It is often unclear to what extent both scapular positioning and biomechanics differ in people with shoulder pain versus people without, as those without shoulder pain also often demonstrate scapular deviations.1,7,19 For instance, although some evidence supports the presence of reduced scapular upward rotation (SUR) and increased scapular anterior tilt in individuals with SAPS,20,21 Navarro-Ledesma et al22 have found decreased SUR in people with chronic shoulder pain compared with people without. To our knowledge there no study determining the association between shoulder pain and disability perceived by the person and scapular biomechanics and scapulothoracic muscle lengths. This information can be relevant in clinical practice, as it may steer rehabilitation programs and help assess patient improvements after treatments.

Hence, the aim of this study was to analyze the level of association between shoulder pain and function and (1) SUR and (2) pectoralis minor and levator scapulae muscle lengths in individuals with unilateral chronic shoulder pain. Our hypothesis was that higher levels of shoulder pain and disability would be associated with decreased pectoralis minor and levator scapulae lengths and changes in SUR.

Section snippets

Study Design

This was a cross-sectional, observational study conducted according to the Declaration of Helsinki. Ethical approval was obtained from the ethics committee of the health care district where the primary-care centers were located (PI9/012014). The study is reported following the recommendations of the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement for observational studies.23 All the participants signed an informed consent form.

Procedure

General practitioners

Sample Characteristics

Sample characteristics are shown in Table 1.

Discussion

This study aimed to analyze whether shoulder pain is related to SUR or the lengths of the pectoralis minor and levator scapulae muscles. The secondary aim was to study the level of association between SUR (45°, 90°, and 135° of shoulder elevation) and the lengths of the pectoralis minor and levator scapulae muscles. The results show that the correlation between shoulder pain and function and the lengths of the pectoralis minor and levator scapulae muscles, as well as SUR (45°, 90°, and 135° of

Limitations and Future Studies

The interrater reliability of measurements was not calculated, and the number of participants is limited. Moreover, although ultrasound assessment is shown to have the best sensitivity and comparable specificity for the detection of partial- and full-thickness tears of the rotator cuff,47 rehabilitative ultrasound imaging is a user-dependent assessment tool, and only 1 examiner carried out the ultrasound evaluation for exclusion criteria. Additionally, advanced equipment exists to assess

Conclusion

The pectoralis minor and levator scapulae muscle lengths and SUR minimally explain shoulder pain and disability, and so their use should be taken with caution in clinical assessment. Other factors, such as psychological factors, central/peripheral sensitization, and intrinsic properties of tissue, need to be taken into account.

Funding Sources and Conflicts of Interest

No funding sources or conflicts of interest were reported for this study.

Contributorship Information

Concept development (provided idea for the research): S.N.-L., A.L.S.

Design (planned the methods to generate the results): M.F.-S., A.L.S.

Supervision (provided oversight, responsible for organization and implementation, writing of the manuscript): F.S., A.L.S.

Data collection/processing (responsible for experiments, patient management, organization, or reporting data): S.N.-L., M.F.-S.

Analysis/interpretation (responsible for statistical analysis, evaluation, and presentation of the results):

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