Effects of scapular dyskinesis and scapular assistance test on subacromial space during static arm elevation

Amee L. Seitz, Philip W. McClure, Stephanie S. Lynch, Jessica M. Ketchum, Lori A. Michener

Research output: Contribution to journalArticle

46 Citations (Scopus)

Abstract

Background: Scapular dyskinesis is an abnormal scapular motion or position during active arm elevation. Dyskinesis is theorized to contribute to impingement syndrome by decreasing the subacromial space. A corrective maneuver of the scapular assistance test (SAT) proposes to increase scapular upward rotation and posterior tilt to increase the subacromial space. The purpose of this study is to determine the influence that 1) scapular dyskinesis and 2) passive manual correction with the SAT have on subacromial space and 3-dimensional (3-D) scapular kinematics. Materials and methods: Forty asymptomatic participants were classified with either obvious dyskinesis (n = 20) or normal motion (n = 20) using the scapular dyskinesis test. The anterior outlet of the subacromial space was measured via the acromiohumeral distance using ultrasound imaging and 3-D scapular orientation was assessed with electromagnetic motion analysis, with the arm at rest 45° and 90° of active elevation with and without the SAT, respectively. Results: There were no differences in acromiohumeral distance or scapular kinematics with static active arm elevation between groups. The SAT increased scapular upward rotation, posterior tilt, and acromiohumeral distance in both groups. Participants with dyskinesis demonstrated greater scapular mobility in upward rotation with the SAT, but no additional increase in acromiohumeral distance. Conclusion: Scapular dyskinesis identified during active motion did not result in different 3-D scapular orientation or acromiohumeral distance during active arm elevation in static positions; however, the SAT altered scapular kinematics and increased acromiohumeral distance. The SAT may be helpful to identify individuals where subacromial compression is producing symptoms, regardless of dyskinesis.

Original languageEnglish (US)
Pages (from-to)631-640
Number of pages10
JournalJournal of Shoulder and Elbow Surgery
Volume21
Issue number5
DOIs
StatePublished - May 1 2012

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Biomechanical Phenomena
Shoulder Impingement Syndrome
Electromagnetic Phenomena
Ultrasonography

Keywords

  • AHD
  • Impingement
  • Scapular assistance test
  • Scapular dyskinesis test
  • Scapular kinematics
  • Shoulder
  • Special tests
  • Subacromial space

ASJC Scopus subject areas

  • Surgery
  • Orthopedics and Sports Medicine

Cite this

Effects of scapular dyskinesis and scapular assistance test on subacromial space during static arm elevation. / Seitz, Amee L.; McClure, Philip W.; Lynch, Stephanie S.; Ketchum, Jessica M.; Michener, Lori A.

In: Journal of Shoulder and Elbow Surgery, Vol. 21, No. 5, 01.05.2012, p. 631-640.

Research output: Contribution to journalArticle

Seitz, Amee L. ; McClure, Philip W. ; Lynch, Stephanie S. ; Ketchum, Jessica M. ; Michener, Lori A. / Effects of scapular dyskinesis and scapular assistance test on subacromial space during static arm elevation. In: Journal of Shoulder and Elbow Surgery. 2012 ; Vol. 21, No. 5. pp. 631-640.
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AB - Background: Scapular dyskinesis is an abnormal scapular motion or position during active arm elevation. Dyskinesis is theorized to contribute to impingement syndrome by decreasing the subacromial space. A corrective maneuver of the scapular assistance test (SAT) proposes to increase scapular upward rotation and posterior tilt to increase the subacromial space. The purpose of this study is to determine the influence that 1) scapular dyskinesis and 2) passive manual correction with the SAT have on subacromial space and 3-dimensional (3-D) scapular kinematics. Materials and methods: Forty asymptomatic participants were classified with either obvious dyskinesis (n = 20) or normal motion (n = 20) using the scapular dyskinesis test. The anterior outlet of the subacromial space was measured via the acromiohumeral distance using ultrasound imaging and 3-D scapular orientation was assessed with electromagnetic motion analysis, with the arm at rest 45° and 90° of active elevation with and without the SAT, respectively. Results: There were no differences in acromiohumeral distance or scapular kinematics with static active arm elevation between groups. The SAT increased scapular upward rotation, posterior tilt, and acromiohumeral distance in both groups. Participants with dyskinesis demonstrated greater scapular mobility in upward rotation with the SAT, but no additional increase in acromiohumeral distance. Conclusion: Scapular dyskinesis identified during active motion did not result in different 3-D scapular orientation or acromiohumeral distance during active arm elevation in static positions; however, the SAT altered scapular kinematics and increased acromiohumeral distance. The SAT may be helpful to identify individuals where subacromial compression is producing symptoms, regardless of dyskinesis.

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