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ID
Source
Brief title
Health condition
Observational study in healthy subjects, to learn more about patients with rotator cuff disease.
Sponsors and support
Reumafonds
Intervention
Outcome measures
Primary outcome
External force controlled Electromyography (EMG).
To measure activation of individual shoulder muscles (in particular: deltoids, supraspinate, infraspinate, pectoralis major, upper and lower trapezius, latissimus dorsi and teres major) and analyze for relative changes in activation of rotator cuff and deltoid muscles with increased arm moment loading.
Conditions: Arm against an external force in 24 directions (humerus fixed in splint, constant exerted abduction force), 2 moment arms (~4 cm and ~29 cm from the glenohumeral joint).
Outcome: Average filtered EMG value (rEMG), principal Action (PA), Activation Ratio (AR) and Max Voluntary Force (MVF), relative change in deltoid and supraspinate activation (rEMG) expressed in percentages.
Secondary outcome
3D-Motion tracking of the scapular position during arm force task with the humerus in a fixed position. To record 3D kinematics of the scapula with a motion tracking system for analyzing the eventual change in scapular position as a result from changes in muscle activations when altering moment loading (with a constant force).
Conditions: Arm against an external force (humerus fixed in a splint, constant exerted force), 2 moment arms (~4 cm and ~29 cm from the glenohumeral joint).
Outcome: 3D scapular positions (scapular posterior tilting, external rotation, and lateral rotation as described in literature) with altering moments and muscle activations.
Background summary
It is generally alleged that mobility in the glenohumeral joint is generated by muscles with relative large force moment arms, while stability in the glenohumeral joint is predominantly guarantied for by muscles close to the joint with relatively small moment arms: the rotator cuff muscles. Consequently, there is a lack of glenohumeral stability in patients with rotator cuff tears, with subsequent relative cranial translation of the humerus and pain. For abduction of the arm, the deltoid would be the main moment generator, with the rotator cuff muscles providing glenohumeral stability. Nevertheless, these beliefs have never been assessed by biomechanical analyses.
Arm motion (e.g. arm muscle forces and moments) and scapular position directly correlate, but it is not clear whether scapulohumoral rhythm has an essential and active role in facilitating arm motions, or if it is simply the result of muscle activations and intended arm motions. The cooperation of muscle activation patterns and scapular position needs to be studied, because distorted scapulohumoral or scapulo-thoracal rhythm is related to subacromial pathologies.
Study objective
We hypothesize that, with increased arm abduction moment loading with a constant exerted abduction force, primary arm moment generators (deltoid muscle) will have a greater increase in activation (EMG) as compared to primary arm/glenohumeral stabilizators (supraspinate muscle).
Study design
Intake and measurements at 1 timepoint.
Intervention
Subjects will be seated, having their dominant arm fixed in a splint. Next, subjects will have to exert isometric forces in directions perpendicular to the long axis of the humerus, using visual feedback.
In a second session, the same approach will be applied, with the same exerted arm force. However, in the second session the exerted force will be applied at a point nearer to th GH-joint.
In this manner, subjects will participate in 2 sessions of measurements using the same exerted force. However, subjects will be subjected to 2 separate amounts of arm moment loading.
During the isometric force tasks, EMG will be recorded using surface electrodes.
P.B. Witte, de
Albinusdreef 2, Room B-0-57
Leiden 2300 RC
The Netherlands
+31 (0)71 5263606
p.b.de_witte@lumc.nl
P.B. Witte, de
Albinusdreef 2, Room B-0-57
Leiden 2300 RC
The Netherlands
+31 (0)71 5263606
p.b.de_witte@lumc.nl
Inclusion criteria
1. Age: between 18 and 60 y.o.;
2. No history of shoulder complaints;
3. No current complaints of the shoulder.
Exclusion criteria
1. No signed informed consent;
2. Pace-maker or other electronic implants.
Design
Recruitment
Followed up by the following (possibly more current) registration
No registrations found.
Other (possibly less up-to-date) registrations in this register
No registrations found.
In other registers
| Register | ID |
|---|---|
| NTR-new | NL2160 |
| NTR-old | NTR2284 |
| Other | ZonMW : 40-00703-98-8564 |
| ISRCTN | ISRCTN wordt niet meer aangevraagd. |