Shoulder pain across more movements is not related to more rotator cuff tendon findings in people with chronic shoulder pain diagnosed with subacromial pain syndrome

Abstract

Introduction: People with chronic shoulder pain commonly report pain during arm movements in daily-life activities. Pain related to movement is commonly viewed as an accurate representation of tissue damage. Thus, when a person reports pain across a variety of movements, this is often understood as indicative of greater damage.

Objectives: We aimed to investigate if movement-related pain that occurs across a wider variety of movements was associated with the number or severity of rotator cuff tendons reported as abnormal on a magnetic resonance imaging (MRI). To answer this question, this study was designed in 3 phases.

Methods: We recruited 130 individuals with chronic shoulder pain diagnosed with subacromial pain syndrome. First, a list of daily functional activities commonly reported as painful by people with chronic shoulder pain was generated from 3 well-established outcome measures with 30 individuals and a measurement tool was developed with data from further 100 individuals, which demonstrated to have acceptable content validity, construct validity, internal consistency, interrater reliability, and structural validity. Multiple linear regression was then used to evaluate the hypotheses of the study. A direct acyclic graph was used to select variables for linear regression modelling.

Results: There was no association between movement-related pain occurrence across movements and the MRI findings.

Conclusion: Our study provides evidence that neither the number of rotator cuff tendons reported as abnormal nor the severity of each tendon imaging finding were associated with pain occurrence across movements and activities commonly perceived as painful by people with chronic shoulder pain.

Keywords: Chronic pain; Rotator cuff; Shoulder pain; Subacromial pain syndrome.

Conflict of interest statement

The authors have no conflict of interest to declare.Sponsorships or competing interests that may be relevant to content are disclosed at the end of this article.

Copyright © 2021 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of The International Association for the Study of Pain.

Figures

Figure 1.

Illustration of the pain distribution across the movements of the scale of 2 subjects of this study. The z axis represents the self-reported pain; the first line of the y axis represents the unilateral reach movements in 60°, 90°, and 120°, respectively; the second line of the y axis represents the bilateral reach movements in 60°, 90°, and 120°, respectively; the third line of the y axis represents the movements of drinking water, combing the hair and placing the hand in the back pocket of the pants. In A, it is possible to observe that pain was perceived with high intensities during overhead reaching movements and while combing the hair. In B, pain was perceived across most movements of the scale with similar pain intensities. Although the Movement-related Pain Distribution Scale—Shoulder (MRPDS) of the first subject was 5 and of the second was 0.8, the Visual Analogue Scale of both were the same—6.8 cm.

Figure 2.

Directed acyclic graph (DAG) describing the conceptual framework used to construct the multiple linear regression models to verify the hypothesis of this study.,,,,,, The Movement-related Pain Distribution Scale—Shoulder (MRPDS) was used as a dependent variable. The independent variables of the first model were (1) number of tendons reported as abnormal and severity of the (2) supraspinatus, (3) infraspinatus, (4) subscapularis, and (5) long head of the biceps imaging finding. In the second model, the variables (6) pain during rest and (7) pain intensity were added to the variables of the previous model as independent variables, and the model was further adjusted by pain duration and number of musculoskeletal complaints.