Shoulder Dislocation & Instability
Evidence-based guide to diagnosis, treatment, and prevention of recurrent shoulder instability
Understanding Shoulder Instability
The shoulder is the most mobile joint in the body, allowing the arm to move in virtually any direction. This mobility comes at a cost—the shoulder is inherently less stable than other joints, making it the most commonly dislocated major joint.
Anatomy: The glenohumeral joint is a ball-and-socket joint where the humeral head (ball) articulates with the glenoid (socket). The glenoid is shallow, providing only 25% coverage of the humeral head. Stability comes from the labrum (cartilage rim), capsule, ligaments, and dynamic muscle control (rotator cuff and scapular muscles).
Epidemiology: Shoulder dislocations account for 50% of all major joint dislocations. Incidence is 23.9 per 100,000 person-years, with peak occurrence in males aged 15-29 (sports/trauma) and females over 60 (falls).
Classification of Shoulder Instability
Most common type. Humeral head displaces forward. Typically occurs with arm in abduction and external rotation.
Associated: Bankart lesion, Hill-Sachs lesion
Rare, often missed. Humeral head displaces backward. Associated with seizures, electric shock, or direct trauma.
Associated: Reverse Hill-Sachs lesion
Instability in multiple directions. Often due to generalized ligament laxity or repetitive microtrauma.
Associated: Capsular redundancy
Traumatic onset
Unidirectional instability
Bankart lesion typically present
Surgery may be required for recurrence
Atraumatic onset
Multidirectional
Bilateral (often)
Rehabilitation primary treatment
Inferior capsular shift if surgery needed
Interval closure
Associated Pathology
Soft Tissue Injuries
• Bankart Lesion: Labral tear (87-100%)
• ALPSA Lesion: Anterior labral periosteal sleeve avulsion
• SLAP Tear: Superior labrum injury
• HAGL Lesion: Humeral avulsion of glenohumeral ligament
• Rotator Cuff Tear: Common in patients >40 years
Bony Injuries
• Hill-Sachs Lesion: Humeral head compression fracture (40-90%)
• Bony Bankart: Glenoid rim fracture (5-56%)
• Greater Tuberosity Fracture: More common in elderly
• Glenoid Track Concept: Engaging vs non-engaging Hill-Sachs
Critical Assessment: In patients over 40, rotator cuff tears occur in up to 35% of first-time dislocations and increase with age. MRI evaluation is essential in this age group before planning treatment.
Clinical Presentation
• Severe pain and muscle spasm
• Visible deformity (squared-off shoulder)
• Arm held in slight abduction and external rotation (anterior)
• Complete inability to move shoulder
• Possible numbness (axillary nerve injury in 5-35%)
• Palpable humeral head in abnormal position
• Episodes of subluxation or dislocation
• “Dead arm” sensation during activities
• Apprehension with arm in vulnerable positions
• Feeling of shoulder “giving way”
• Decreased confidence in shoulder
• Activity limitation and avoidance
Diagnostic Evaluation
Instability Tests:
• Apprehension Test: Positive when patient feels impending dislocation with arm in 90° abduction and external rotation
• Relocation Test: Relief of apprehension with posterior pressure on humeral head
• Anterior/Posterior Drawer: Assesses translation of humeral head
• Sulcus Sign: Inferior laxity assessment for MDI
• Load and Shift: Quantifies glenohumeral translation
• AP, Lateral (Y-view), Axillary
• Confirm dislocation direction
• Identify fractures
• West Point view for bony Bankart
• Stryker notch for Hill-Sachs
• Gold standard for soft tissue
• Labral tears (Bankart, SLAP)
• Capsular pathology
• Rotator cuff integrity
• Cartilage assessment
• Bone loss quantification
• Glenoid track assessment
• 3D reconstruction planning
• Essential if surgery planned
Evidence-Based Treatment
Treatment recommendations based on systematic reviews, Cochrane database, and guidelines from ISAKOS, ASES, and published long-term outcomes studies.
Closed Reduction: Prompt reduction under sedation/analgesia using gentle techniques (Stimson, Cunningham, external rotation method). Neurovascular assessment before and after reduction is mandatory.
Post-Reduction: Confirm reduction with X-rays, immobilize in sling, ice, and analgesia.
Our Approach for First-Time Dislocations:
We recommend structured rehabilitation as first-line treatment for most first-time shoulder dislocations. This evidence-based approach focuses on:
Phase 1 - Protection (Weeks 0-3):
• Sling immobilization for comfort (2-3 weeks)
• Pain and inflammation control
• Gentle pendulum exercises when pain allows
Phase 2 - Early Rehabilitation (Weeks 3-8):
• Progressive range of motion exercises
• Rotator cuff strengthening - Internal/external rotation exercises
• Scapular stabilization (Scapular Setting) - Critical for dynamic stability
• Core stability integration
Phase 3 - Advanced Strengthening (Weeks 8-16):
• Progressive resistance training
• Proprioceptive training
• Sport-specific conditioning
• Gradual return to activity
Evidence: Studies show that a comprehensive rehabilitation program focusing on rotator cuff and scapular muscle strengthening can reduce recurrence rates by 20-40%. The key is completing the full program before returning to high-risk activities.
Indications for Surgery:
• Recurrent dislocations (2 or more episodes) despite rehabilitation
• Significant bone loss (>20% glenoid or engaging Hill-Sachs)
• Failed conservative treatment with ongoing instability
• Associated repairable pathology (rotator cuff tear, bony fracture)
Arthroscopic Bankart Repair
• Gold standard for soft-tissue instability without significant bone loss
• Suture anchor repair of labrum to glenoid rim
• Success rates: 85-95% in appropriately selected patients
• Advantages: Minimally invasive, faster recovery
Latarjet Procedure (Bone Block)
• For significant glenoid bone loss (>20-25%)
• Coracoid transfer to anterior glenoid
• Provides bone augmentation + sling effect
• Lowest recurrence rates (2-5%)
Remplissage Procedure
• For engaging Hill-Sachs lesions
• Infraspinatus tenodesis into humeral head defect
• Often combined with Bankart repair
Recovery & Return to Activity
• Sling: 2-3 weeks
• Range of motion: 3-6 weeks
• Strengthening: 6-12 weeks
• Non-contact sports: 3 months
• Contact sports: 4-6 months
Success depends on commitment to rehabilitation program
• Sling: 4-6 weeks
• Passive/active-assisted ROM: 6-10 weeks
• Strengthening: 10-16 weeks
• Non-contact sports: 4-5 months
• Contact sports: 6-9 months
Stabilization success rate: 90-95%
Key to Success: Regardless of treatment path, completing the full rehabilitation program is essential. Premature return to activity before adequate strength and control is regained significantly increases re-injury risk.
Scientific References & Guidelines
1. Bankart ASB. The pathology and treatment of recurrent dislocation of the shoulder joint. Br J Surg. 1938
2. Cochrane Review: Surgical versus conservative treatment for acute anterior shoulder dislocation
3. ISAKOS Scientific Committee: Consensus Statement on Shoulder Instability
4. Burkhart SS, De Beer JF. Traumatic glenohumeral bone defects and their relationship to failure of arthroscopic Bankart repairs. Arthroscopy. 2000
5. Di Giacomo G, et al. The Glenoid Track Concept. AJSM. 2014
6. Olds M, et al. Risk factors for recurrence after first traumatic anterior shoulder dislocation: a systematic review. Br J Sports Med. 2015
Last Updated: January 2025 | Content reviewed by Dr. Deepthi Nandan Reddy, FRCS (Ortho)
