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J Shoulder Elbow Surg. 2014 Mar;23(3):e61-7. doi: 10.1016/j.jse.2013.06.009. Epub 2013 Sep 4.

Differences in muscle activities during shoulder elevation in patients with symptomatic and asymptomatic rotator cuff tears: analysis by positron emission tomography.

Author information

  • 1Department of Orthopaedic Surgery, Tohoku University School of Medicine, Sendai, Japan.
  • 2Department of Orthopaedic Surgery, Tohoku University School of Medicine, Sendai, Japan. Electronic address: sanohirotaka@med.tohoku.ac.jp.
  • 3Division of Cyclotron Nuclear Medicine, Cyclotron and Radioisotope Center, Tohoku University, Sendai, Japan.

Abstract

BACKGROUND:

Differences in muscle activity patterns between patients with symptomatic and asymptomatic full-thickness rotator cuff tears have not yet been fully clarified. The purpose of this study was to investigate the muscle activity pattern by use of positron emission tomography (PET) in patients with symptomatic and asymptomatic rotator cuff tears.

METHODS:

Ten shoulders of 9 patients with full-thickness rotator cuff tears were divided into 2 groups by a numerical pain rating scale (0-10), symptomatic (≥2) and asymptomatic (0 or 1), with 5 shoulders each. Scaption exercise of bilateral arms (200 repetitions in 10 minutes) with a weight of 0.25 kg each was performed before and after injection of fluorodeoxyglucose. After PET examination, the standardized uptake value of each muscle was calculated to quantify its activity and compared between the two groups.

RESULTS:

The activity of the anterior and middle deltoid was significantly decreased in the symptomatic group compared with the asymptomatic group (anterior deltoid, P = .02; middle deltoid, P = .03). In contrast, the activity of the superior trapezius was significantly increased in the symptomatic group compared with the asymptomatic group (P = .02).

CONCLUSION:

In patients with a symptomatic tear, the deltoid activity was decreased and the trapezius activity was increased. It is likely that they might have moved the painful glenohumeral joint less and instead moved the painless scapulothoracic joint more during the prescribed exercise. We conclude that patients with painful rotator cuff tears use the parascapular muscles more than those without pain do during arm elevation.

Copyright © 2014 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Mosby, Inc. All rights reserved.

KEYWORDS:

Shoulder pain; arm elevation; asymptomatic rotator cuff tear; muscle activity; positron emission tomography

PMID:
24012359
[PubMed - indexed for MEDLINE]
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