7. Approach to shoulder instability.pptx

shoulder instability approach

1. Approach to shoulder instability SPORT SURGERY & REHABILITATION EAST COAST SYMPOSIUM 2024

2. Outline Introduction Anatomy and Pathoanatomy of genohumeral joint instability Evaluation Management

3. Introduction The glenohumeral joint is minimally constrained and designed for mobility, places the joint at risk for instability. The most dislocated joint, accounts for more than 50% of all joint dislocations. Anterior dislocation constitutes most of the shoulder dislocations with a rate of more than 95%. 90% risk of recurrent anterior shoulder instability in patient <20 years old if treated non operatively after first time dislocation

4. Anatomy and Physiology of GH Joint Stability Static stabilizer Articular anatomy of a joint with matched concavity and convexity of the ball-in-socket- articular congruity Glenoid labrum Glenohumeral ligaments Negative intraarticular pressure –secondary to high osmotic pressure in interstitial tissue causes vacuum effect provide stability when the shoulder in abduction Rotator interval Dynamic stabilizers rotator cuff musculature biceps tendon Scapulothoracic and humeral motion Proprioception The perception of motion of the joint A failure of proprioceptive feedback may contribute to instability.

5. Static stabilizer Glenoid labrum Fibrocartilaginous bumper that forms a circumferential ring around the glenoid and serves as an anchoring point for the capsuloligamentous structures. Deepens glenoid by 5-9 mm contributes 50% of additional glenoid depth Acts as a ‘chock-block’ Suction action Anchor for the ligaments and long head of biceps

6. Static stabilizer Glenohumeral ligaments Thickening of the anterior and inferior portions of shoulder capsule. SGHL, MGHL, IGHL Act the extremes of range of motion Different glenohumeral ligaments will tighten according to the specific position of the arm and control humeral head translation to provide stability

7. SGHL - Limit posterior translation with the arm in flexion, adduction, and internal rotation. MGHL Primarily limits anterior humeral head translation with the arm abducted to 45 degrees and externally rotated. Limit external rotation and inferior translation when the arm is in the adducted position IGHLC- Anterior band, axillary pouch, posterior band. Prevent anterior translation when the arm in abduction and external rotation Limit posterior translation when the arm internal rotation and abduction

8. Static stabilizer Negative Intra-articular Pressure The IAP is 4 mmHg below atmospheric Very hard to pull the two articular surfaces from each other Venting the capsule reduces force for anterior translation by 55% (Gibb et al)

9. Dynamic stabilizer The deltoid and the rotator cuff dynamically compress and center the humeral head within these concavities during shoulder motion enhancing GH joint stability Provide stability compression of the humeral head into the glenoid and coracoacromial arch concavities - concavity-compression effect

10. Dynamic stabilizer The periscapular muscles dynamically position the scapula to place the glenoid opposite the humeral head as the shoulder move (ball on a seal’s nose)

11. Patho anatomy in shoulder instability The anterior glenohumeral instability mostly occurs with a traumatic episode Hyperabduction and external rotation - generation of a force from posterior to anterior displaces the humeral head out of the glenoid – anterior shoulder dislocation. In the traumatic anterior instability, failure can occur at any region of the anterior capsulolabral restraint – essential lesions of shoulder instability

12. Essential lesions The Bankart lesion The anterior labrum is disrupted from the glenoid along with disrupted periosteum of the scapular neck and it typically lies anterior to the glenoid. Approximately 90 % of all anterior instability has the Bankart lesion ALPSA -Anterior Labroligamentous Periosteal Sleeve Avulsion The torn labroligamentous structures still attached to scapular periosteum are displaced and healed on the medial surface of the anterior glenoid neck

13. GLAD- Glenolabral Articular Disruption Disruption of articular cartilage from the anterior inferior glenoid surface either as a flap tear or cartilage loss and is caused by a forced adduction injury to the shoulder from an abducted and external rotated position. HAGL - Humeral Avulsion of Glenohumeral Ligament Detachment of the glenohumeral ligament from the humeral attachment 1–9 % in anterior shoulder instability.

14. Patho anatomy Gleno humeral bone defect/ bone loss/ fracture Impaction of posterosuperior lateral aspect of humeral head onto anterior inferior glenoid rim Hill Sach lesion - posterosuperior lateral aspect of humeral head bone defect

15. on-track and off-track Hill Sachs lesions A concept used to assess the risk of a Hill-Sachs lesion engaging with the glenoid rim with or without a glenoid defect Glenoid track- zone of contact between the glenoid and the humeral head Hill-Sachs defect is "off-track" and will "engage" on the glenoid if the size of the Hill-Sachs defect > glenoid articular track (HSI > GT) Hill-Sachs defect is "on track" and will NOT "engage" if the size of the Hill-Sachs defect < glenoid articular track (HSI < GT) Directly affected by glenoid bone loss and the size of Hill- Sachs lesion

16. Bony bankart – anterior inferior glenoid defect The size of glenoid bone defect is associated with recurrent high risk of recurrent instability Defect >21% is considered "critical bone loss" and is biomechanically highly unstable Stability cannot be restored with soft tissue stabilization alone (unacceptable >2/3 failure rate) Requires bony procedure to restore bone loss

17. Classification Based on etiologies – Thomas and Matsen classification TUBS (traumatic, unilateral, bankart , and surgery) AMBRI (atraumatic, multidirectional, bilateral, rehabilitation, and inferior capsular shift) Stanmore polar classification- multifactorial etiologies with the third aspect of the triangle represented by muscle patterning instability. Direction of instability-Anterior, posterior, multidirectional instability

18. EVALUATION History Physical examination Imaging

19. History Mechanism of injury/ traumatic event leading to dislocation Direction of dislocation How the shoulder was reduced? How many time the shoulder has dislocated in the past? Age at first dislocation? Symptoms- sense of instability/ shoulder pain

20. Suspect significant glenoid bone loss in patient with: high-energy mechanism of injury arm abduction and extension at the time of initial dislocation, most instability occurring at midrange of motion (20deg to 60deg of abduction) instability during normal activities of daily living, and a long history of instability ( Povencher et al)

21. PHYSICAL EXAMINATION Load and shift test to assess of the amount of passive glenohumeral translation Done at neutral, 45 deg and 90 deg GH elevation for anterior translation Graded 0– III Posterior translation is assessed with mild IR with varying degree of shoulder abduction

22. Apprehension test Provocative testing to reproduce the symptoms and/or apprehensions of the patient. Patient supine with arm 90 degrees abducted and 90 degrees externally rotated Positive - patients apprehensive that his/her shoulder going to dislocate/ subluxate Positive sign in mid-ranges of abduction is highly suggestive of concomitant glenoid bone loss Relocation sign decrease in apprehension with anterior force applied on shoulder during apprehension testing

23. Assessment of generalized patient laxity is important for determining etiology and planning management. Increased risk of recurrent instability in patients with hyperlaxity Beighton's criteria (score > 4) – poor reliability sulcus sign- tested with patient's arm at side shoulder specific laxity measures: hyperexternal rotation at side > 85 degress hyperabduction > 105 degrees ( Gagey's maneuver)

24. Radiograph – to assess gross lesions, rule out fracture AP view Inferior glenoid defect- bony bankart lesion AP (internal rotation) – Hill Sachs lesion Axillary view- assess the position of humeral head in glenoid cavity Bony Bankart lesion Hill sachs lesion

25. Stryker notch – Hill Sachs lesion west point view and Bernageau profile- shows glenoid bone loss

26. CT Scan Useful for evaluation of bony injuries Calculation of glenoid bone loss using “ en face”sagittal view with 3D reconstruction Assessment of on track and off track lesion in Hill-Sachs lesion / bipolar lesion

27. MRI MRI is the most useful modality for evaluating the soft tissues of the shoulder joint. Abduction and external rotation (ABER) sequences can be utilized to better visualize the antero-inferior glenoid labrum MRA-increases sensitivity and specificity (86-91% and 86-96%) for detecting soft-tissue injuries when compared to conventional MRI (44-100% and 66-95%) Has been validated as an imaging modality through which to assess bone loss

28. Management

29. Acute dislocation Reduction under sedation/ anaesthesia Radiograph post reduction – confirm reduction, exclude fractures Immobilization in arms ling 1 week - no improvement in rate of recurrence instability after prolonged immobilization Physical therapy -strengthening of dynamic stabilizers (rotator cuff and periscapular musculature)

30. Surgery Indication Recurrent instability First time dislocation in young patients/ athletes Soft tissue procedures vs bony procedures

31. Surgical options Address the essential lesions Arthroscopic soft tissue stabilization- arthroscopic Bankart repair and capsular plication Mobilization of capsulolabral complex Fixation of capsulolabral complex to the glenoid Minimum 3 - 4 suture anchors Outcome: recurrence 6.3%- 35.3%

32. Arthroscopic Bankart repair with Remplissage procedure Medium to large engaging/off-track Hill-Sachs lesion Remplissage - fill the Hill-Sachs lesion with capsule and infraspinatus tendon to prevent the Hill- sachs lesion from engaging the anterior inferior glenoid Recurrence- 5% at 2 years

33. Laterjet Patte procedure Indication: anterior instability with critical (>20-25%) or subcritical (>13.5%) bone loss patients at high-risk of failure with soft-tissue procedures alone (ISIS > 4-6 points) Coracoid transfer to anterior inferior glenoid bone defect

34. Triple blocking effect Structural bone graft providing extra diameter to the glenoid Sling effect of the inferior subscapularis by the conjoint tendon in abducted shoulder Anterior capsule augmentation by reinserting and shortening the inferior capsular pouch on a small flap of coracoacromial ligament attached the coracoid. Outcome- recurrence 0-9.6% Surgical complications- up to 25%, commonly infection

35. Recommended treatment algorithm based on glenoid bone loss and patient factors (expectations/ age/ lifestyle)

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