| Shoulder electromyography in multidirectional instability. | |
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MedLine Citation:
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PMID: 14735069 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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We studied shoulder muscle activity in multidirectional instability (MDI) and multidirectional laxity (MDL) of the shoulder, our hypothesis being that altered muscle activity plays a role in their pathogenesis. Six muscles (supraspinatus, infraspinatus, subscapularis, anterior deltoid, middle deltoid, and posterior deltoid) were investigated by use of intramuscular dual fine-wire electrodes in 7 normal shoulders, 5 MDL shoulders, and 6 MDI shoulders. Each subject performed 5 types of exercise (rotation in neutral, 45 degrees of abduction, 90 degrees of abduction, flexion/extension, and abduction/adduction) on an isokinetic muscle dynamometer at two rates, 90 degrees /s and 180 degrees /s. After filtering, rectification, and smoothing, the electromyography signal was normalized by using the peak voltage of the movement cycle. In subjects with MDI, compared with normal subjects, activity patterns of the anterior deltoid were different during rotation in neutral and 90 degrees of abduction, whereas those of the middle and posterior deltoid were different during rotation in 90 degrees of abduction. In subjects with MDL, the posterior deltoid showed increased activity compared with normal subjects during adduction. Activity patterns of the supraspinatus, infraspinatus, and subscapularis appeared similar in both groups. Dual fine-wire electromyography offers insight into the complex role of shoulder girdle muscle function in normal movement and in instability. Altered patterns of shoulder girdle muscle activity and imbalances in muscle forces support the theory that impaired coordination of shoulder girdle muscle activity and inefficiency of the dynamic stabilizers of the glenohumeral joint are involved in the etiology of MDI. Interestingly, the abnormalities are in the deltoid rather than the muscles of the rotator cuff. |
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Authors:
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Alfred D Morris; Graham J Kemp; Simon P Frostick |
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Publication Detail:
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Type: Comparative Study; Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Journal of shoulder and elbow surgery / American Shoulder and Elbow Surgeons ... [et al.] Volume: 13 ISSN: 1058-2746 ISO Abbreviation: J Shoulder Elbow Surg Publication Date: 2004 Jan-Feb |
Date Detail:
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Created Date: 2004-01-21 Completed Date: 2004-06-01 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 9206499 Medline TA: J Shoulder Elbow Surg Country: United States |
Other Details:
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Languages: eng Pagination: 24-9 Citation Subset: IM |
Affiliation:
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University Department of Musculoskeletal Science, Royal Liverpool University Hospital, Liverpool, United Kingdom. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Adult Electromyography / methods* Exercise Test Humans Joint Instability / physiopathology* Muscle, Skeletal / physiopathology* Muscular Diseases / diagnosis* Reproducibility of Results Rotator Cuff / physiopathology Shoulder Shoulder Joint* |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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