- To investigate whether increased arm moment loading (with a constant exerted abduction force) in healthy controls leads to a relatively larger increase in deltoid muscle activation as compared to increase in supraspinatus muscle activation.- To…
ID
Source
Brief title
Condition
- Joint disorders
Synonym
Research involving
Sponsors and support
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.
* 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.
Secondary outcome
Delft Shoulder and Elbow Model (DSEM) simulation
Computer Model Analysis of the effect of increase in arm abduction moment
loading (with the humerus in a fixed position and a constant exerted force) on
relative increase of deltoid and supraspinate muscle activations.
There is no extra effort of patients needed for these data.
Conditions: Constant external abduction force on 2 separate distances from the
glenohumeral joint (~4 and ~29 cm).
Outcome: inversed dynamics (individual muscle forces, direction and magnitude
of joint reaction forces).
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
- To investigate whether increased arm moment loading (with a constant exerted
abduction force) in healthy controls leads to a relatively larger increase in
deltoid muscle activation as compared to increase in supraspinatus muscle
activation.
- To assess the influence of altered muscle activation patterns in healthy
controls, as a response on increased abduction moment loading, on scapula 3D
position.
Study design
Intervention response test (repeated measures) in healthy controls.
Study burden and risks
The subjects will be invited for one visit at the Laboratory for Kinematics and
Neuromechanics at the Leiden University Medical Center, which will take around
80 minutes. Subjects will participate in simple biomechanical task
measurements, during which muscle activation patterns will be recorded with EMG
(11 surface electrodes, one wire electrode). Additionally, sensors will be
placed on bony landmarks to measure 3D scapular position. These sensors and the
surface electrodes do not cause any risk to the participants, the wire
electrode can cause minimal discomfort when inserting the wire, but the skin is
anaesthetized with Lidocaine.
Travel expenses will be compensated for, and subjects will receive a ¤25.00
gift certificate.
The results of this study will help us further understand subacromial
pathologies, such as shoulder impingement syndrome and rotator cuff tears, in
order to optimize treatment pathways.
As supraspinatus function is impaired in patients, the objectives for this
study can only be met by using data obtained from healthy subjects (intact
shoulder muscles).
Postbus 9600
2300 RC Leiden
Nederland
Postbus 9600
2300 RC Leiden
Nederland
Listed location countries
Age
Inclusion criteria
- Age: between 18 and 60 y.o.
- No history of shoulder complaints
- No current complaints of the shoulder
Exclusion criteria
- No signed informed consent
- 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 |
|---|---|
| CCMO | NL30946.058.09 |