Humeral head translation after a suprascapular nerve block

Subacromial impingement syndrome is the most common shoulder disorder. Abnormal superior translation of the humeral head is believed to be a major cause of this pathology. The first purpose of the study was to examine the effects of suprascapular nerve block on superior translation of the humeral he...

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Bibliographic Details
Published in:Journal of applied biomechanics 2013-08, Vol.29 (4), p.371-379
Main Authors: San Juan, Jun G, Kosek, Peter, Karduna, Andrew R
Format: Article
Language:English
Subjects:
Adult
Computer Simulation
Female
Humans
Humeral Head - physiology
Knee
Male
Models, Biological
Motion
Muscle Contraction - physiology
Muscle, Skeletal - innervation
Muscle, Skeletal - physiology
Nerve Block
Range of Motion, Articular - physiology
Scapula - physiology
Shoulder Joint - physiology
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Summary:Subacromial impingement syndrome is the most common shoulder disorder. Abnormal superior translation of the humeral head is believed to be a major cause of this pathology. The first purpose of the study was to examine the effects of suprascapular nerve block on superior translation of the humeral head and scapular upward rotation during dynamic shoulder elevation. The secondary purpose was to assess muscle activation patterns during these motions. Twenty healthy subjects participated in the study. Using fluoroscopy and electromyography, humeral head translation and muscle activation were measured before and after a suprascapular nerve block. The humeral head was superiorly located at 60 degrees of humeral elevation, and the scapula was more upwardly rotated from 30 to 90 degrees of humeral elevation after the block. The differences were observed during midrange of motion. In addition, the deltoid muscle group demonstrated increased muscle activation after the nerve block. The study's results showed a compensatory increase in humeral head translation, scapular upward rotation, and deltoid muscle activation due to the nerve block. These outcomes suggest that increasing muscular strength and endurance of the supraspinatus and infraspinatus muscles could prevent any increased superior humeral head translation. This may be beneficial in reducing shoulder impingement or rotator cuff tears over time.
ISSN:1065-8483
1543-2688
DOI:10.1123/jab.29.4.371