1996 Fiscal Year Final Research Report Summary
A electromyographic study of the function of the biceps in patients with rotator cuff tears.
| Project/Area Number |
07671565
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Orthopaedic surgery
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| Research Institution | AKITA UNIVERSITY |
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Principal Investigator |
ITOI Eiji AKITA UNIVERSITY,SCHOOL OF MEDCINE,LECTURER, 医学部, 講師 (80193465)
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| Project Period (FY) |
1995 – 1996
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| Keywords | biceps brachii / rotator cuff tear / electromyography |
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| Research Abstract |
Eighteen shoulders of 16 patients who had full-thickness tears of the rotator cuff and who were able to elevate their arms more than 120ﾟ were enrolled in this study (cuff-tear group). The diagnosis of rotator-cuff tear was established either by arthrography or magnetic resonance imaging (MRI). As a control, 22 asymptomatic shoulders with normal MRI findings of the rotator cuff were studied. Electromyographic activities of the biceps were investigated to fetermine the role of the biceps in cuff-deficient shoulders. Using surface electrodes, biceps activities were recorded during arm elevation in the scapular plane with and without 1-kg load. The percentages of integrated electromyograms to those during maximum voluntary contraction (%MVC) were obtained at 30ﾟ, 60ﾟ, 90ﾟ, and 120ﾟ of elevation.
In the normal shoulders, %MVC of the biceps was always less than 10% through the arc of elevation both with and without load. Among 18 shoulders with rotator-cuff tears, 6 shoulders showed increased activities of the biceps more than 10% in %MVC (p<less than or equal>0.0042), whereas the rest 12 showed activities similar to the normal shoulders. The biceps activities in these 6 shoulders increased with load application (p=0.0395) and in higher angles of elevation (p=0.0003). The muscle strength tended to be weaker in shoulders with increased biceps activities than in those without. Increased activities of the biceps suggest a potential supplemental function of this muscle in shoulders with rotator-cuff
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