Scapular Dyskinesis

1. Scapular Dyskinesis • Ian S Rice MD

2. 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

3. 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

4. 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

5. Pec Minor • Short and tight • Increased scapular internal rotation and anterior tilting

6. Scapula Winging • Lateral Winging • Medial Winging

7. 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

8. 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

9. Stages of Throwing

11. Wind Up • Minimal force through the shoulder • Inactive rotator cuff muscles • Development of torso and leg force

12. Early Cocking • Peak Deltoid activation

13. Late Cocking • Peak muscle activation: Supra/infraspinatus, teres minor • High torque phase: max external rotation of shoulder • Glenohumeral internal rotation deficit • Internal impingement

14. 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

15. Deceleration • Eccentric contraction of all muscles to counter torque and slow arm motion

16. Follow Through • Distraction forces must be resisted by posteroinferior capsule

17. 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

18. 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

19. 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

20. 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

22. Development of a SLAP Tear • Tight posteroinferior capsule and GIRD develop increased peel-back 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

24. 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

25. 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

26. 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

27. Kinetic Chain: Scapula • Retracts and protracts around the thoracic wall during the throwing motion • Moves with humerus to avoid hyperangulation of humerus on glenoid

28. 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

29. 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

30. Identifying “shoulder at risk” • Shoulders with: • Glenohumeral internal rotation deficit • Malpositioned SICK scapula • Anatomy • Posterosuperior labrum • Posterior supraspinatus tendon • Anterior inferior capsular structures

31. 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

32. 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

33. Scapular Retraction Test • Manually positioning and stabilizing the entire medial border of the scapula • Positive • Increased muscle strength • Decreased pain with Jobe relocation test

34. 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

35. 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

36. Patterns of Dyskinesis • Type I - inferior medial scapular border prominence • Type II - medial scapular border prominence • Type III - superomedial scapular border prominence

37. 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)

38. 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

39. 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

40. Need to address whether flexibility deficits are primary or secondary • If flexibility is the issue, then address that prior to motor control learning

41. 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

42. 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

43. 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

44. 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

45. 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)

46. Low Row • Trunk extension, scapular retraction, arm extension as patient pushes posteriorly

47. Wall Washes

48. 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

50. 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