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Scapular Dyskinesis
• Ian S Rice MD
Muscles of the Scapula
Pec Minor
Coracobrachialis
Biceps (short head)
Biceps (long head)
Serratus Anterior
Triceps (long head)
Subscapularis
Rhomboid Major/Minor
Levator Scapulae
Trapezius
Deltoid
Supraspinatus
Infraspinatus
Teres Major
Teres Minor
Latissimus Dorsi
Omohyoid
Infraspinatus
Max cross sectional area
1.8 to 9 times larger compared to supraspinatus and teres
minor
High eccentric loading during overhead pitching
Shortens and limits glenohumeral internal rotation and
horizontal adduction ROM
Associated with tightness of posterior shoulder structures
Infraspinatus Function
Produce glenohumeral joint compression
Create a downward pull on the humeral head
to minimize superior migration
Decelerator during overhead throwing
motion
Resists shoulder internal rotation and horizontal
adduction
Pec Minor
Short and tight
Increased scapular internal rotation and anterior
tilting
Scapula Winging
Lateral Winging
Medial Winging
Medial Winging
Deficit of Serratus Anterior
Innervated by long thoracic nerve
Caused by repetitive stretch, compression, scapula fx, laceration of
nerve
Inferior border of scapula goes medial
Treatment:
Nonop - observe for 6 months for return of nerve function
Operative - pec major transfer with fascia lata graft
Lateral Winging
Deficit of trapezius
Spinal accessory or Dorsal scapular nerve
Iatrogenic - ex. dissection for lymph nodes
Inferior border of the scapula goes lateral
Treatment
Eden-Lange transfer
Lateralize insertion of levator scapulae and rhomboids
Stages of Throwing
Wind Up
Minimal force
through the shoulder
Inactive rotator cuff
muscles
Development of torso
and leg force
Early Cocking
Peak Deltoid activation
Late Cocking
Peak muscle activation: Supra/infraspinatus, teres minor
High torque phase: max external rotation of shoulder
Glenohumeral internal rotation deficit
Internal impingement
Acceleration
Triceps activation
Pec major, lat dorsi, serratus anterior activation
At ball release - 4 body motions
Trunk rotation, shoulder internal rotation, elbow extension,
wrist flexion
20% reduction in trunk kinetic energy requires 33% more
velocity or 70% more mass at distal segments to maintain
same energy at ball impact
Deceleration
Eccentric contraction
of all muscles to
counter torque and
slow arm motion
Follow Through
Distraction forces
must be resisted by
posteroinferior
capsule
Development of “Dead Arm”
Overhead athlete first develops tightness in back of the shoulder
Posteroinferior capsular contracture
Causes a posterosuperior shift in glenohumeral rotation point
Peel back forces in late cocking causes a SLAP lesion
Mechanical symptoms dictate surgical treatment
Hyperexternal rotation of the humerus increases the clearance of the
greater tuberosity over the glenoid and reduces the humeral head cam
effect on anterior capsule
Scapular protraction develops
Pathoanatomy of “Dead Arm”
External rotation forces causes repetitive
“microtrauma” to the anterior capsule
Hyperexternal rotation and hyperhorizontal
abduction
Loss of internal rotation in abduction
Less than the external rotation gain
Caused by posterior inferior capsular
contracture
Impingement itself is not pathologic
All shoulders with in abduction with external
rotation show impingement
Glenohumeral internal rotation deficit
(GIRD)
Definition: Degree loss of internal rotation
Measured with shoulder abducted in plane of the body and scapula stabilized by
downward pressure to the anterior shoulder
Measure to the point where the scapula moves on the posterior chest wall
Tethered Shoulder
Posterior capsule contraction
Posterior band of the IGHL exerts a posterosuperior
force on the humeral head
Glenohumeral contact point is shifted and can have more
external rotation before impingement
Cam effect of the humeral head and proximal humeral
calcar on the anteroinferior capsule is reduced by the
shift
Development of a SLAP Tear
Tight posteroinferior capsule and
GIRD develop increased peelback forces and increased shear
forces on the labrum
Peel back occurs due to bicep
tendon vector shifting to a more
posterior position in late cocking.
Torsional force to rotate
medially over corner of glenoid
Role of the Scapula
Link between trunk and arm
Transfers and increases the energy, power,
and equilibrium from lower extremities and
trunk
Kinetic Chain Theory
Kinetic Chain
Coordinated sequencing of multiple segments to
maximize power
Legs and trunk act as force generators
Shoulder acts a funnel and force generator
Arm acts as a force delivery mechanism
Only 50% of velocity is developed from the
arm/shoulder
Kinetic Chain: Legs and Trunk
Provides rotational momentum for force generation
Able to generate 50-55% of total force and kinetic
energy in a tennis serve
Weakness in hip abductors or trunk flexors increases
lumbar lordosis during arm acceleration
Hyperabduction/external rotation position at the
shoulder and increases posterior compression loads
Kinetic Chain: Scapula
Retracts and protracts around
the thoracic wall during the
throwing motion
Moves with humerus to avoid
hyperangulation of humerus
on glenoid
The Cascade
Acquired posteroinferior capsule contracture
Max shear stress on posterosuperior labrum
Inferior axillary pouch structures are imbalanced
Posterosuperior shift of humeral head
Shear forces at biceps anchor and posterosuperior labral attachment
increase
Anterior capsule structures become lax
Excessive external rotation caused by GIRD leads to increased shear and
torsional stress in the posterosuperior rotator cuff
Causes of Dyskinesis
Bony causes
Thoracic kyphosis
Clavicle fracture non-union or shortened malunion
Joint causes
AC instability or arthrosis
GH joint internal derangement
Neurological causes
Cervical radiculopathy
Long thoracic or spinal accessory nerve palsy
Soft Tissue causes
Stiffness of pec minor or short head of biceps —> anterior tilt and protraction
GIRD —> reduced humeral head internal rotation and horizontal abduction
Identifying “shoulder at risk”
Shoulders with:
Glenohumeral internal rotation deficit
Malpositioned SICK scapula
Anatomy
Posterosuperior labrum
Posterior supraspinatus tendon
Anterior inferior capsular structures
Clinical Clues
Medial and inferior scapular borders for
winging or prominence
Lack of smooth coordinated movement as
exemplified by early scapular elevation
Shrugging during ascending arm forward
flexion and rapid downward rotation during
arm lowering from full flexion
Scapular Assistance Test
Assisting scapular upward rotation
by manually stabilizing upper
medial border and rotating the
inferomedial border as arm is
abducted
Positive result
Relief of impingement
symptoms and weakness
Scapular Retraction Test
Manually positioning and
stabilizing the entire medial
border of the scapula
Positive
Increased muscle strength
Decreased pain with Jobe
relocation test
SICK Scapula
Scapular malposition
Inferior medial border prominence
Coracoid pain and malposition
dysKinesis of the scapular movement
Clinical Presentation
Anterior shoulder pain (coracoid) , posterosuperior scapular pain, superior
shoulder pain, proximal lateral arm pain
Inferior position, lateral displacement, abduction
SICK Scapula
Coracoid pain with passive forward
flexion
Pec minor & short biceps tendon
“tightness”
Lowers leading edge of acromion
causing impingement from
anteroinferior angulation
Levator scapulae is placed under
tension when scapula tilts and rotates
laterally
Decreased subacromial space
Patterns of Dyskinesis
Type I - inferior medial scapular border
prominence
Type II - medial scapular border prominence
Type III - superomedial scapular border
prominence
Poor posture
Prolonged sitting tasks leads to forward head posture, increased thoracic kyphosis, and
protraction of shoulder girdle
Reduced clavicle retraction
Increased clavicle elevation
Scapular upward rotation
Scapular posterior tilt
Slouched posture affects scapular orientation, shoulder muscle strength and ROM
Altered serratus anterior muscle activity
Force imbalance in upper and lower trapezius muscle
Flexibility deficits (pec minor tightness, posterior glenohumeral capsular stiffness)
Dyskinesis and Neck Pain
No consensus about relationship
Noted to be a risk factor for shoulder pain
Possible predisposition to develop shoulder pain, and
then is exacerbated by it
Typical finding of bilateral scapular dyskinesis in
patients with shoulder pain
Worse on affected side
Rehabilitation
Need to determine patient goals
Office worker: correction of axioscapular muscles,
scapular orientation with arms by the sides, and
during prolonged upper limb activities
Overhead Athletes: advanced scapular muscle
control and strength in sport specific movements
Need to address whether flexibility deficits are primary or secondary
If flexibility is the issue, then address that prior to motor control learning
Rehab of Flexibility Defects
Scapular level
Pec Minor and Levator Scapulae
Scapular retraction in 30 deg of flexion
Largest change in pec minor length
Glenohumeral Level
Posterior shoulder structures, capsule, external rotator muscles
Sleeper stretch
Sleeper Stretch
90% of throwers with symptomatic GIRD (greater than 25
deg) will respond to stretching.
Acceptable: less than 20 deg or less than 10% of total
rotation in non throwing shoulder.
Period of time: 2 weeks
Rehab of Muscle Motor Control
Neuromuscular deficits (lack of co-contraction
and force couple activity)
Upper Trap hyperactivity
Strength deficits
Serratus anterior, Middle and Lower Trap
Conscious Muscle Control
Activating Lower Trap
Patient palpates coracoid and then focuses on “pulling the coracoid from
his finger and moving the scapula backwards”
Creates posterior tilt and upward rotation
Counters a SICK scapula
Spinal Posture Correction
Neutral lumbopelvic posture, with correction of scapulothoracic and
cervical postures
“Occipital lift” of the head
Muscle Control and Strength
Open Chain Exercises
Low Row, Inferior Glide, Lawnmower
Closed Chain Exercises - require less activation than open chain
Pushing hands on thighs in upright sitting, Wall sliding exercise, Pushups
Want exercises with low Upper Trap/Lower Trap, Upper Trap/Middle Trap, and Upper Trap to Serratus Anterior ratios
Support the arm (wall slide and bench slide exercises)
Intramuscular Trapezius training
Side lying external rotation, side lying forward flexion, prone horizontal abduction with external rotation and prone
extension
Early activation of lower trapezius
Diagonal patterns including lower limb and core muscle activity favor scapular muscle activity (lower trapezius)
Low Row
Trunk extension,
scapular retraction,
arm extension as
patient pushes
posteriorly
Wall Washes
Advanced Sports Movements
Last stage of rehab
Goal: exercise advanced scapular muscle control and strength
Attention to integration of the kinetic chain into the exercise
program, plyometric and eccentric exercises
Throwers use weight balls and elastic resistance tubing
Swimmers should focus on exercises while prone
W-V exercise
Total Time: 12 weeks to 6 months
Summary
Posterior inferior capsular contracture
Leads to GIRD
Then posterior superior cuff internal impingement
Which develops posterosuperior SLAP tear
Resulting in Anterior capsular stretching
Scapular protraction
OITE
23 yo professional pitcher complains of posterior shoulder pain. Physical
exam is notable for scapular dyskinesis. No intra-articular pathology is found
on shoulder MRI. Which of the following should be emphasized in the initial
stages of rehabilitation?
1) Isometric shoulder exercises
2) Isokinetic shoulder exercises
3) Closed chain shoulder exercises
4) Coordination of scapular motion with trunk and hip movements
5) Axial loading shoulder exercises
4
Scapular dyskinesis is an alteration in the normal motion of the scapular during
coordinated scapulohumeral movements. It occurs as a sequela of prior
shoulder injury, especially injuries disrupting the activation patterns of scapular
stabilizing muscles. Kibler et al outlined a rehabilitation protocol to treat
scapular dyskinesis. The principle is to treat the problem proximal to distal. The
first stage involves attaining full motion of the scapular and coordinating the
scapula with trunk and hip motions. Once this has been achieved, the second
stage involves strengthening the scapular musculature. As scapular control is
attained, exercises are introduced that place emphasis on the shoulder and arm
beginning with flexibility and closed-chain strengthening, eventually working up
to sport-specific functions. Progress is determined by functional improvement
rather than a strict time table.