Scapular dyskinesis

Simon J Roche et al., Shoulder & Elbow 2015, Vol. 7(4) 289–297

1. Simon J Roche et al. 雙和醫院 復健醫學部 楊政道醫師 Scapular dyskinesis Shoulder & Elbow 2015, Vol. 7(4) 289–297

2. Scapular dyskinesis A collective term that refers to ‘ movement of the scapula that is dysfunctional ’ and may create a possible impairment of overall shoulder function Loss of control of normal scapular motion, physiology or mechanics Good scapula control and positioning Optimal positioning of the humerus in relation to the glenoid Transferring power from the core to the distal upper extremity

3. Anatomical concepts of the scapula Skeletal attachment: Acromioclavicular joint GH joint Sternoclavicular joint Muscular attachment: Trapezius muscle Serratus anterior muscle Rhomboid muscle Pull the scapula forward around the thorax Antagonist to the rhomboids

4. Movement of scapula ‘ Upward/downward rotation ’ around a horizontal axis perpendicular to the plane of the scapula ‘ Internal/external rotation ’ around a vertical axis through the plane of the scapula ‘ Anterior/posterior tilt ’ around a horizontal axis in the plane of the scapula

5. The coupling movement of scapula-1 Retraction: external rotation, posterior tilt, upward rotation, and medial translation ★ Clear the acromion from the moving arm in elevation and abduction “ 上 後 外 ”

6. The coupling movement of scapula-2 Protraction: internal rotation, anterior tilt, downward rotation, and lateral translation

7. The coupling movement of scapula-3 Shrug: upward translation, anterior tilt, and internal rotation

8. The importance of coupling movement ‘ Internally/externally rotation ’: maintain glenoid as a congruent socket, maximizing concavity compression and ball and socket kinematics Stabilized in ‘ retraction posture ’ during use of arm to achieve maximal activation of all muscles originating on the scapula

9. Scapular stability and mobility The trapezius and serratus anterior muscles: initiate upward rotation and posterior tilting ★ Clear the acromion from the moving arm in elevation and abduction

10. Scapular stability and mobility Lower trapezius : stabilize the arm in overhead position and in descent of the arm from maximal elevation Romboid muscle: assist in controlling medial and lateral scapula translation Latissimus dorsi and pectoralis minor muscles (shoulder girdle muscles) : prime movers of arm

11. Scapular stability and mobility The force couples for scapular stabilization: ‘Upper/lower trapezius + Serratus anterior’ paired with ‘Rhomboid muscles’ The fore couple for acromial elevation: ‘Lower trapezius + Serratus anterior’ paired with ‘Upper trapezius + Rhomboid’

12. Force couples for scapula motion-1 The upper and lower trapezius and serratus anterior muscles have long lever arms, being effective rotators and stabilizers.

13. Force couples for scapula motion-2 With higher arm elevation, the upper trapezius moment arm is shorter, whereas the lower trapezius and serratus anterior moment arms remain long, continuing to rotate the scapula.

14. Force couples for scapula motion-3 With maximum arm elevation, the lower trapezius maintains scapula position and the instant center of rotation moves from the medial border of the spine to the acromioclavicular joint.

15. The clinical characteristics In a static sense ‘Prominence of the scapula’ ‘A resting position of protraction ’ Prominence of the ‘ medial or inferomedial scapular border’ ‘ Early scapular elevation or shrugging ’ on arm elevation ‘Rapid downward rotation’ on lowering of the arm

16. The joint causes of dyskinesis High-grade AC arthrosis and instability Glenohumeral joint internal derangement

17. The bony causes of dyskinesis Thoracic kyphosis Clavicular fracture, non-union Clavicular malunion with shortening, rotation or angulation

18. The neurological causes of dyskinesis Palsies of the long thoracic or spinal accessory nerves Long thoracic nerve: serratus anterior muscle Spinal accessory nerve: trapezius muscle Cervical radiculopathy Long thoracic nerve palsy (Medial scapula winging) Spinal accessory nerve palsy (Lateral scapula winging )

19. Dorsal scapular nerve palsy (another type of scapula winging) Weak rhombid and levator scapula

20. The soft tissue causes of dyskinesis Intrinsic muscle pathology Inflexibility Inhibition of normal muscle activation “Commonest” Decreased flexibility of either ‘ the short head of biceps muscle’ or ‘ pectoralis minor’ have been shown to create anterior tilt and internal rotation of the scapula as a result of their pull on the coracoid The muscles attaching at coracoid process: pectoralis minor, coracoradialis , and short head of biceps

21. The soft tissue causes of dyskinesis Intrinsic muscle pathology Inflexibility Inhibition of normal muscle activation “Commonest” Reduced strength and activation of ‘ serratus anterior’ muscle causes loss of posterior tilting and upward rotation of scapula

22. Protraction Not favorable for optimal shoulder function Poor position for muscle activation Decreased subacromial space with increased impingement and rotator cuff compression Decreased rotator cuff strength Increase in strain of the anterior glenohumeral ligaments A greater risk of internal impingement

23. Scapular dyskinesis and specific shoulder injuries

24. Labral injury Internal rotation Anterior tilting Increased strain of anterior ligament Increased ‘peel-back’ of the biceps/labral complex on the glenoid Pathological internal impingement GH joint ‘ internal rotation’ deficit Tight ‘ posterior’ structure of shoulder Increased protraction Protraction

25. Scapular d yskinesis with labral injury Modified dynamic labral shear test Rehabilitation to improved scapular retraction Mobilization of ‘tight anterior muscle’ ‘Strengthening’ for scapular stability Correct S/S by manual scapular retraction Scapular dyskinesis as part of pathophysiology

26. D ynamic labral shear test Arm abduction to 120 degree in scapular plane Shear load applied by maximal external rotation Arm lowered from 120 to 60 degree Pain , click or catch between 120 and 90 degree

27. Impingement In throwing athletes Mostly associated with instability , labral injury , and biceps pathology Scapular dyskinesis in impingement Loss of acromial upward rotation Excessive scapular internal rotation Excessive scapular anterior tilting Protraction Decreased the subacromial space Decreased rotator cuff strength

28. Altered activation patterns in impingement Increased upper trapezius activity Shrung maneuver → lack acromial elevation Imbalance of upper/lower trapezius activation Late lower trapezius activation → lack acromial elevation and posterior tilting Decreased serratus anterior activation Lack scapular external rotation and elevation (upper rotation/posterior tilting) with arm elevation Tight (shortened) pectoralis minor muscle Protracted scapular at rest Lack posterior tilting and/or external rotation while arm motion

29. Rotator cuff injury Anterior tilting and internal rotation of glenoid Increased internal impingement on posterior superior glenoid with arm external rotation Increased torsional twisting of the rotator cuff

30. Tight upper trapezius & pectoralis minor & short head of biceps Weak lower trapezius and serratus anterior Tight supraspinatus & infraspinatus Tight supraspinatus & infraspinatus & long head of biceps & ant. deltoid Tight post. d eltoid & supraspinatus & infraspinatus & teres minor

31. AC joint injuries AC joint separation / type II injury (torn ligament with joint laxity) Remove the strut function of clavicle on the scapula Allow scapula to move inferiorly and medially to the clavicle Allow excessive scapula protraction and decrease acromial elevation when elevating arm Impingement with decreased rotator cuff strength

32. Clavicle fracture Shortened mal-unions or non-unions Decreased the length of strut Internal rotation and anterior tilting of scapula Changes of clavicle curvature or rotation Changes of clavicle length Angulated fractures Functional shortening Loss of rotation The distal fragment in mid-shaft fracture often internally rotate Decrease posterior rotation of clavicle and posterior tilting of scapula while arm elevation

33. Clinical examination of the scapula

34. Scapula assistance test Manually stabilizing the scapula and rotating the inferior border of the scapula as the arm moves Evaluates scapular contributions to impingement and rotator cuff strength Simulates the force-couple activity of the serratus anterior and lower trapezius muscles If S/S improved, rehabilitation of the scapular stabilizing muscles

35. Scapula retraction test Manually stabilizing the scapula in a retracted position on the thorax Evaluation of labral symptoms and rotator cuff strength Confers a stable base of origin for the rotator cuff and improve rotator cuff strength Demonstrates scapular and glenoid involvement in impingement lesions

36. Scapula retraction test with resistance or scapular resistance test (a) (b) The examiner performs a traditional ‘empty can’ test (90 degree of shoulder abduction and 30 degree of forward flexion ad maximal internal rotation) The examiner stabilizes the medial border of the scapula and repeats the test. If the impingement symptoms are relieved ( strength of supraspinatus muscle is increased or S/S of internal impingement in the labral injury is decreased ) , the test is positive.

37. Lateral scapula slide test (a) Initial position with arm at side. (b) Second position, arms on hips. (c) Third position with arms at 90 degree and internal rotation. Quantitative assessment of scapular stabilizer strength The threshold of abnormality is 1.5 cm and significant asymmetry is most commonly measured in the third position.

38. Investigation of scapular dyskinesis X-ray: clavicle and AC joint injury EMG/NCV: long thoracic/ thoracodorsal/ accessory spinal nerves MRI: muscle/tendon injuries MRA: labral pathology

39. Treatment of scapular dyskinesis

40. Rehabilitation plan-1 Decrease muscle inhibition of per-scapular/GH joint muscles Relieve the symptoms associated with ‘inflexibility’ or trigger points Re-establish ‘muscle strength’ and ‘activation patterns’ Soft tissue related pathology such as labral injury , internal impingement , or rotator cuff pathology Hard tissue injury such as clavicle fractures and AC separations

41. Rehabilitation plan-2 Core stability exercise Scapular control exercise Serratus anterior muscle: powerful external rotator Lower trapezius : stabilizer for scapular position Short lever and kinetic chain assisted exercise Long lever exercise Rotator cuff strength and/or exercise for internal impingement

42. Core stability exercise The larger muscles of the ‘lower extremity’ and trunk are utilized during the treatment of the scapula and shoulder Scapular protraction and retraction are facilitated by ‘hip and trunk’ flexion and ‘extension’ exercises . Can improve 3D control of scapular motion

43. Summary Scapular dyskinesis is likely to be a major contributor to shoulder pain, particularly in cases of recalcitrant shoulder pain and dysfunction . It is advisable that this condition is recognized as a constituent of the routine shoulder examination for shoulder surgeons.