Subacromial injection improves deltoid firing in subjects with large rotator cuff tears. Academic Article uri icon

Overview

abstract

  • Previous studies demonstrate that scapulohumeral mechanics improve after subacromial injection. However, it is unclear how injection affects muscle firing. Forty-one subjects with two-tendon rotator cuff tears and 23 volunteer subjects with normal rotator cuffs documented by ultrasonography were examined. Electromyographic activity from 12 muscles was collected during ten functional tasks. Nine symptomatic subjects with rotator cuff tears underwent subacromial injection of anesthetic and underwent repeat electromyographic examination. Subjects with rotator cuff tears demonstrate global electromyographic differences when compared to normal controls. Asymptomatic subjects with rotator cuff tears had significantly increased anterior deltoid firing when compared to symptomatic counterparts during forward shoulder elevation. After subacromial injection, symptomatic subjects demonstrate increased anterior deltoid firing. Previous in vitro and in vivo studies have suggested that pain leads to deltoid inhibition and that subacromial injection leads to improved deltoid firing and, subsequently, improved shoulder function. This study provides direct evidence that subacromial injection improves deltoid firing in symptomatic subjects with rotator cuff tears. These findings reinforce the concept that deltoid inhibition resulting from pain is an important component of the motor disability associated with rotator cuff tears.

publication date

  • September 18, 2009

Identity

PubMed Central ID

  • PMC2821485

Scopus Document Identifier

  • 0030001889

Digital Object Identifier (DOI)

  • 10.1177/036354659602400307

PubMed ID

  • 19763696

Additional Document Info

volume

  • 6

issue

  • 1