Moment arms of the deltoid, infraspinatus and teres minor muscles for movements with high range of motion: A cadaveric study

Hoffmann, M., Begon, M., Assila, N., St-Pierre, M.-O., Bertrand-Grenier, A., Duprey, S. et Sobczak, S. (2022). Moment arms of the deltoid, infraspinatus and teres minor muscles for movements with high range of motion: A cadaveric study. Clinical Biomechanics . Article 105685. ISSN 0268-0033 DOI 10.1016/j.clinbiomech.2022.105685

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Résumé

Background
Moment arms are an indicator of the role of the muscles in joint actuation. An excursion method is often used to calculate them, even though it provides 1D results. As shoulder movement occurs in three dimensions (combination of flexion, abduction and axial rotation), moment arms should be given in 3D. Our objective was to assess the 3D moment arms of the rotator cuff (infraspinatus and teres minor) and deltoid muscles for movements with high arm elevation.
Methods
The 3D moment arms (components in plane of elevation, elevation and axial rotation) were assessed using a geometric method, enabling to calculate the moment arms in 3D, on five fresh post-mortem human shoulders. Movement with high range of motion were performed (including overhead movement). The humerus was elevated until it reaches its maximal posture in different elevation plane (flexion, scaption, abduction and elevation in a plane 30° posterior to frontal plane).
Findings
We found that the anterior deltoid was a depressor and contributes to move the elevation plane anteriorly. The median deltoid was a great elevator and the posterior deltoid mostly acted in moving the elevation plane posteriorly. The infraspinatus and teres minor were the greatest external rotator of the shoulder. The position of the glenohumeral joint induces changes in the muscular moment arms. The maximal shoulder elevation was 144° (performed in the scapular plane).
Interpretation
The knowledge of 3D moment arms for different arm elevations might help surgeons in planning tendon reconstructive surgery and help validate musculoskeletal models.

Type de document:	Article
Mots-clés libres:	Moment arms Glenohumeral joint Geometric method Shoulder measurement
Date de dépôt:	04 juill. 2022 18:42
Dernière modification:	26 mai 2023 04:00
Version du document déposé:	Post-print (version corrigée et acceptée)
URI:	https://depot-e.uqtr.ca/id/eprint/10220

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