Scapular dyskinesia

Dr VV Vinay Vivek
• scapula dyskinesis, “the abnormal anatomy and kinetics of the
scapular” and with the aim to (a) improve the understanding of the
biomechanical principles of the scapular function, (b) study related
pathophysiology in different disease processes and (c) delineate the
rehabilitation regimes available for the management of the disease.
• the acromioclavicular joint, supported by the Trapezoid and Conoid
ligaments attaching to the coracoid process and the acromioclavicular
joint capsule which incorporates the acromioclavicular ligament.
• The clavicle serves three roles:
• Supports the arm, keeping the humerus away from the thorax;
• Protects the cervicoaxillary canal;
• Acts as a means of force transfer from the core to the arm
• The second joint is the glenohumeral joint which is stabilized by four
anterior ligaments, the superior, middle and inferior glenohumeral
ligaments and the coracohumeral ligament. Posterior stability is aided
by the posterior capsule.
• In addition to the articulating joints, there is the articulation between
the scapula and thorax to consider. Although no bony articulation
occurs here, it is allowing a vast degree of “gliding” movement in a 3-
dimensional plane. The role of the scapular and its muscular
attachments is to dynamically control the position of the glenoid to
allow optimal biomechanical movement at the glenohumeral
movement joint.
• Scapular biomechanics
• The scapula serves four biomechanical roles:
• It is the centre of rotation of the humerus.
• It is the anchor of the humerus onto the thoracic wall.
• It keeps the acromion from obstructing the movement of the
humerus both in abduction and in flexion, thus there is no
impingement.
• It is the means by which forces are transmitted from the core to the
arm.
• Elevation/depression;
• Protraction/retraction;
• Internal/external rotation;
• Superior/inferior rotation;
• Anterior/posterior tilt.
• the first 30 degrees of flexion and 60 degrees of abduction of the humerus,
the scapula seeks to find a position of stability to optimize the power of these
movements. In some cases, either the scapula would remain fixed with the
glenohumeral joint being the principle area of movement or the scapula would
translate medially or laterally to assist the glenohumeral motion. The study
concluded that for early degrees of movement, the movement of the scapula
was person-specific, with variation seen. The optimal position that the scapula
found was termed the setting phase. Once flexion or abduction exceeded
those levels, the behaviour of the scapula was much more uniform, with a
ratio of movement between glenohumeral and scapulothoracic angle of 2:1,
for instance for 15 degrees extension of the humerus, 10 degrees would occur
at the glenohumeral joint, 5 degrees at the scapulothoracic.
• More recent studies have suggested a less variable pattern of scapular
movement, with the key component being upward rotation, followed
by posterior tilt and external rotation. Research has highlighted that
the upper and lower trapezius along with serratus anterior are the
muscles that mostly affect scapular movement and cause dykinesia.
When the scapula biomechanics are considered in relation to the
anatomy, it becomes evident that the combination of movements,
planes and muscles involved there is a vast array of combinations that
could lead to abnormal movement function
Scapular pathophysiology/pathomechanics
The causes of scapular dyskinesis can be split into three groups:
• Shoulder-related;
• Neck-related;
• Posture-related
• (1) acromioclavicular instability, (2) shoulder impingement, (3) rotator
cuff injuries, (4) glenoid labrum injuries, (5) clavicle fracture and (6)
nerve-related. The common characteristic of all these pathologies is
the disturbance of the scapulohumeral rhythm
• 1) “mechanical neck pain” syndromes and
• 2) cervical nerve root-related syndromes.
 Posture-related causes of scapular
dyskinesis
• Excessive thoracic kyphosis and cervical lordosis alter the resting
position of the scapula. Athletes are more susceptible to these
changes. Depending on their sport, they develop core muscle
imbalances that alter spinal curvatures and soft tissue tensions
• (1) Direct observation; (2) Manually Assisted Movements and (3)
Assessment of surrounding structures
• To perform Direct observation of the scapula the patient’s resting
scapular position is assessed followed by the observation of active
movements; stands and holding a 1-kg bag and is asked to perform
simple active movement; shoulder flexion and abduction, whilst the
examiner observes for winging, early elevation, rapid downward
rotation and shoulder shrugging. The findings are noted as a yes/no
answer, followed with a description of the best performance
• Manually assisted movements of scapula: two tests are involved in this step, the
scapular assistance test (SAT) and the scapular reposition (retraction) test (SRT). The
SAT involves the examiner pushing the inferior-medial border of the scapula outwards
and upwards whilst stabilizing the upper medial border when the patient has his
humerus elevated. This test assesses how different the pain is perceived. In a positive
test the pain is reduced and it is usually positive in patients with painful arc or shoulder
impingement.
• There are no false positives in asymptomatic patients . In SRT the examiner has to
position and stabilize the medial scapular border with one hand, whilst the patient is
asked to elevate his arm isometrically (no change in the angle of the joint) against the
examiner’s other hand. Again the test is positive when this manoeuvre reduces the
pain felt by the patient. This test is also positive if the patient’s strength is increased
during the isometric elevation of the arm. The scapular reposition test is sufficiently
specific and sensitive in rotator cuff injuries
• ) Assessment of surrounding structures: the structures around the
scapula (thoracic spine, the acromioclavicular joint, rotator cuff
muscles, two heads of the biceps and the glenoid labrum) are
assessed. It is important to assess these structures thoroughly in
order to exclude or confirm alternative causes of the symptoms. The
assessor is looking for symptoms (pain, loss of function) in other
structures, soft tissue laxity and muscle power
• The main goal of therapy is to improve the kinematic chain at
different levels from the cervical and thoracic spine to the shoulder.
The clinical assessment should identify if scapular dyskinesis is a
deficit in soft tissue mobility or muscle action.
• Deficits in flexibility include different muscle groups and joint
components. The mainstay treatment is stretching of the affected
structure to increase the working length. The pectoralis muscle is best
stretched by the technique “unilateral corner stretch”, a technique
that involves the passive abduction of the humerus at 90 degrees
from the resting position
• The posterior capsule of the glenohumeral joint best responds to
techniques such as “sleep stretch” and “cross body stretch” which
improve the mobility of the joint
• The rehabilitation of muscle activation patterns is split into three
stages: (1) “active conscious control”, (2) “strength and control for
daily activities” and (3) “control in athletic performance”. The muscles
involved are the serratous anterior and the three parts of the
trapezius (superior, middle, inferior)
• The average prescribed duration of such programmes is 12 weeks
with satisfactory functional outcomes . Specific groups that have
higher needs such as volleyball players should undergo longer
programmes, around 3 months .
• The rehabilitation of muscle activation patterns is split into three
stages: (1) “active conscious control”, (2) “strength and control for
daily activities” and (3) “control in athletic performance”. The muscles
involved are the serratous anterior and the three parts of the
trapezius (superior, middle, inferior)
• The average prescribed duration of such programmes is 12 weeks
with satisfactory functional outcomes . Specific groups that have
higher needs such as volleyball players should undergo longer
programmes, around 3 months .
• 1. Active conscious control
• The scapular musculature requires re-orientation in order to re-engage the correct pattern
of activation. The inferior part of the trapezius can be orientated with “scapular
orientation exercise” that promotes targeted re-engagement of the muscle under tactile
feedback from the other limb. Research has shown that conscious training of the muscles
has definite improvements in the kinematic chain but the results can be reversed.
• Further to the rehabilitation of the muscles, the surrounding structures need to be
involved. Especially, the resting position of the spine needs to be addressed. The patient is
taught how to maintain a neutral spinal position, respecting the curvatures of the spine at
the different levels. This retraining begins from the lumbar spine, followed by the thoracic
and finally the cervical spine. The effect is to re-engage the paraspinal stabilizing muscles
to maintain a neutral spinal position. It is advised the patients practice this activity
multiple times throughout the day [
• https://www.youtube.com/watch?v=RvCXOsxGbwU
• 2. Strength and control for daily activities
• The main concept of this stage is concurrent activation of muscles in
order to perform activities of daily life. The prescription should
include both “open-chain” and “closed-chain” activities. The exercises
should be repeated under different weight bearing conditions. “Open-
Chain” activities include “low row”, “inferior glide”, “lawnmower” and
“robbery” exercises, that re-engaged the rhomboid muscle “Closed-
Chain” activities aim to promote the awareness of the joint in space
(proprioception) and coordination of the rotator cuff muscles.
Moreover, muscle strength can be achieved by engaging the deficient
muscles in isolation whilst minimizing the activity of the stronger ones
• 3. Control in athletic performance
• Depending on the sport and the functional needs of the individual, a
detailed prescription of muscle strengthening exercises should adhere
to the principles of “scapular control” and “task specific muscle
strength”
• The scapula is an under-appreciated component of the shoulder
kinematic chain. The importance is highlighted by the significant
improvements in functional ability after rehabilitation.
• Clinical evaluation of the scapular resting position and function is
paramount for the prescription of the necessary physical therapy
exercises.