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Original Article

The Korean Journal of Pain 2020; 33(1): 60-65

Published online January 1, 2020 https://doi.org/10.3344/kjp.2020.33.1.60

Copyright © The Korean Pain Society.

Evaluation of the cross-sectional area of acromion process for shoulder impingement syndrome

Young Joo1,* , Hyung Rae Cho2,* , and Young Uk Kim1

1Department of Anesthesiology and Pain Medicine, Catholic Kwandong University International St. Mary’s Hospital, Catholic Kwandong University College of Medicine, Incheon, Korea
2Department of Anesthesiology and Pain Medicine, Myongji Hospital, Hanyang University College of Medicine, Goyang, Korea

Correspondence to:Young Uk Kim
Department of Anesthesiology and Pain Medicine, Catholic Kwandong University International St. Mary’s Hospital, Catholic Kwandong University College of Medicine, 25 Simgok-ro 100beon-gil, Seo-gu, Incheon 22711, Korea
Tel: +82-32-290-3570
Fax: +82-32-290-3568
E-mail: uk201@hanmail.net

*These authors contributed equally to this work.

Received: July 9, 2019; Revised: September 10, 2019; Accepted: September 16, 2019

This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Background

Anatomic changes in the acromion have been considered a main cause of shoulder impingement syndrome (SIS). To evaluate the relationship between SIS and the acromion process, we devised a new morphological parameter called the acromion process cross-sectional area (APA). We hypothesized that the APA could be an important morphologic diagnostic parameter in SIS.

Methods

We collected APA data from 95 patients with SIS and 126 control subjects who underwent shoulder magnetic resonance imaging (MRI). Then we measured the maximal cross-sectional area of the bone margin of the acromion process on MRI scans.

Results

The mean of APAs were 136.50 ± 21.75 mm2 in the male control group and 202.91 ± 31.78 mm2 in the male SIS group; SIS patients had significantly greater APAs (P < 0.001). The average of APAs were 105.38 ± 19.07 mm2 in the female control group and 147.62 ± 22.90 mm2 in the female SIS group, and the SIS patients had significantly greater APAs (P < 0.001). The optimal APA cut-off in the male group was 165.14 mm2 with 90.2% sensitivity, 91.4% specificity, and an area under the curve (AUC) of 0.968. In the female group, the optimal cut-off was 122.50 mm2 with 85.2% sensitivity, 84.9% specificity, and an AUC of 0.928.

Conclusions

The newly devised APA is a sensitive parameter for assessing SIS; greater APA is associated with a higher possibility of SIS. We think that this result will be helpful for the diagnosis of SIS.

Keywords: Acromion, Anatomy, Cross-Sectional, Diagnosis, Osteophyte, Parameter, Process, Shoulder, Shoulder Impingement Syndrome