Shoulder Instability Basics

1. Shoulder Instability Basics 18 February 2010

2. Contents • Terminology • Anatomy • Pathophysiology • Evaluation • Nonoperative Treatment • Operative Treatment • Treatment Course/Outcomes

3. Terminology • Laxity • Asymptomatic, passive translation of the humeral head on the glenoid unassociated with pain • Instability • Symptomatic pain/apprehension associated with excessive translation of the humeral head during active motion

4. Shoulder Anatomyand Function

5. Skeletal Anatomy

6. Skeletal Anatomy

7. Osteology • Glenoid version • 30o anterior • Humerus • Neck-shaft – 130o to 140o • Retrotorsion – 30o

8. Superficial Anatomy

9. Rotator Cuff Anatomy

10. GHJ Anatomy

11. GHJ Anatomy (cont’d)

12. Labrum • Fibrocartilaginous ring • Anchors capsuloligamentous structures • Deepens the glenoid • Doubles depth • Increases Surface area

13. SGHL • Most constant ligament – but variable thickness • 3 variations of origin • Inserts into top of humerus near tip of lesser tuberosity

14. Function-SGHL • Limit inferior translation and external rotation when arm is adducted • Limit posterior translation when the arm flexed, add, IR

15. Rotator Interval • Triangular area of tissue from supraspinatus superiorly to subscapularis inferiorly • Capsule thickened by SGHL & CH lig • Defects - ?? Significance

16. MGHL • Most variable • Sheetlike or cordlike • Originates from labrum or neck of glenoid just inf to SGHL • Inserts just medial to lesser tub closely opposed to subscap

17. Function • Limits anterior translation with 60o to 90o abduction and ER • Limits inferior translation with the arm adducted

18. IGHL • Anterior band, axillary pouch, posterior band • Originates from labrum/glenoid neck • Ant band – 2 to 4 o’clock • Post band – 7 to 9 o’clock • Inserts into anatomic neck humerus – 90o arc

19. Function • Limits anterior, posterior, and inferior translation depending on arm position • aIGHL limits AP translation in ext, pIGHL limits AP translation in flex

20. Capsuloligamentous Structures

21. Instability Pathophysiology • Most motion of any joint • Dynamic and Static Restraints • Bankart lesion • Avulsion of IGHL & Labrum complex • HAGL

22. Stability • Static Factors • Articular Congruence • Articular Version • Glenoid Labrum • Capsule and Ligament

23. Pathology-version • Glenoid dysplasia • 1% to 3% of instability cases • Avoid surgery

24. Glenoid Rim Fracture • Reduces contact area and glenoid concavity • Less than 25% to 33% involvement not a problem if IGHL is reattached

25. Hill-Sachs Lesion • Impression fracture of posterolateral humeral head • Little consequence if soft tissue repair is performed • Some say greater than 30% involvement may lead to continued instability

26. Bankart Lesion • Detachment of anteroinferior labrum • IGHL is key • Essential lesion?? • Speer, et al: JBJS 76A, 1994

27. Capsular Injury • Acute tears • HAGL lesion • Plastic deformation • Bigliani, et al: JORS, 1992 • Circle concept • Need for capsular shift & failure of scope repairs

28. Stability • Dynamic Factors • Rotator Cuff • Biceps Tendon • Negative Pressure • Scapulothoracic motion

29. Rotator Cuff • Compression enhances conformity • Greater than static stabilizers • Coordinated contractions/steering effect • Supraspinatus most important • Dynamization

30. Scapulothoracic Motion • 2:1 glenohumeral to scapulothoracic motion • Scapulothoracic muscle (trapezius, serratus anterior) weakness produces winging less stable platform

31. Negative Intra-articular Pressure • -42 cm H2O in cadaver • Secondary to high osmotic pressure in interstitial tissues • Only clinically important in the arm at rest in adduction • with lax capsule or defect

32. Static Factors Articular Congruence Articular Version Glenoid Labrum Capsule and Ligament Dynamic Factors Rotator Cuff Biceps Tendon Negative Pressure Scapulothoracic motion Stability

33. TUBS Traumatic Unidirectional Bankart lesion Surgery AMBRII Atraumatic Multidirectional Bilateral Rehabilitation Inferior capsule Interval closure Instability Categories Thomas & Matsen, JBJS(1989)

34. Multidirectional Instability • Definition: • symptomatic increased translation of humeral head on glenoid. • Can be subluxated or dislocated, in three directions with reproduced symptoms with one or more of these directions.

35. MDI • No Single Etiology • Inherent Ligamentous Laxity • Trauma (Major/Repetitive Minor) • Scapular Mechanics

36. A Spectrum Traumatic Microtrauma Atraumatic Less laxity More laxity Unidirectional Multidirectional

37. Instability Classification: • Frequency • Direction • Degree • Etiology

38. Classification • Frequency • Acute • Recurrent • Fixed (chronic) • Cause • Traumatic event (macrotrauma) • Atraumatic event (voluntary, involuntary) • Microtrauma • Congenital condition • Neuromuscular condition (cerebral palsy, seizures)

39. Instability • Patient Evaluation

40. Position of Instability Traumatic/Atraumatic Onset of Symptoms===> Need for Reduction Psychiatric Component Family History Inf. Instab.– pain with carrying suitcase/shopping bags @ side Ant. Instab. – throwing, reaching objects – ABD/ER Post. Instab. – pushing heavy doors FF/IR History

41. Anterior Instability • Traumatic, acute, dislocation • Traumatic, acute, subluxation • Recurrent anterior instability • Chronic recurrent anterior dislocations • Chronic recurrent anterior subluxation • Fixed (locked) anterior dislocation

42. Posterior Instability • Traumatic acute dislocation • Traumatic acute subluxation • Recurrent posterior instability • Recurrent posterior dislocation • Recurrent posterior subluxation • Voluntary • Positional • Muscular • Chronic (locked) dislocation • <25% of articular surface • 25-40% of articular surface • <40% of articular surface

43. Multidirectional Instability • Type I - Global, atraumatic, instability • Type II - Anterior/inferior instability Macrotrauma in setting of hyperlaxity • Type III - Posterior/inferior instability Microtrauma in setting of hyperlaxity • Type IV - Anterior/posterior instability

44. Clinical Evaluation - History • Careful history is paramount • 1st episode of dislocation or subluxation • Degree of trauma - major, trivial, none • Dislocation vs. subluxation • Position of arm • More frequent episodes • Treatment

45. History - Present Symptoms • Arm “slips out” • Dead arm syndrome • Pain • Anterior/posterior pain = ant/post instability • Pain in context of arm position • Cocking vs. follow-through • Carrying heavy items • Secondary impingement • Popping/clicking

46. History- cont’d • Functional losses • ADLs vs. sports • Activity modification • Voluntary control • Positional • Muscular

47. Physical Examination • Inspection • Palpation/ROM Ligamentous laxity Load-Shift test Apprehension test/ Relocation test Sulcus sign RC pathology

48. Physical Examination • Examine both shoulders • Cervical spine • Generalized ligamentous laxity

49. Generalized Joint Laxity Tests • Passive thumb apposition • Passive finger hyper-extension so finger parallels forearm • Elbow hyper-extension >10 degrees • Knee hyper-extension >10 degrees • Excessive ankle dorsiflexion and foot eversion Carter and Wilkinson in (Brown CORR, 2000)

50. Shoulder Exam • Muscular atrophy • Tenderness • AC and SC joint tenderness • ROM - active & passive • Winging • Muscle strength • Supraspinatus - 90o scap elevation/45o int rot • Infraspinatus - 0o scap elevation/ -45o rot • Subscapularis - lift-off/ Napolean’s • Deltoid/Biceps/triceps/trapezius