Shoulder Dislocation

**Shoulder dislocation** occurs when the humeral head separates completely from the glenoid socket. The shoulder is a ball-and-socket joint with remarkable range of motion — the socket (glenoid) is shallow relative to the size of the humeral head, providing flexibility at the expense of stability. **Stabilizing Structures of the Shoulder:** - **Glenoid labrum** — fibrocartilage rim deepening the socket - **Joint capsule** — fibrous envelope - **Glenohumeral ligaments** — reinforcing bands - **Rotator cuff muscles** — dynamic stabilizers - **Long head of biceps tendon** — additional stabilization **Types of Dislocations:** **Anterior Dislocation (90-95%):** - Humeral head displaced FORWARD - Common mechanism: arm forced into abduction and external rotation (like blocking a tackle or falling on outstretched hand) - Classic exam finding: arm held slightly abducted and externally rotated - Visible "squared off" shoulder - Patient unable to bring arm across body - Often associated with [Bankart lesion](/condition/shoulder-dislocation) (labral tear) and Hill-Sachs lesion **Posterior Dislocation (5-10%):** - Humeral head displaced BACKWARD - Common mechanism: seizure, electrocution, fall onto adducted arm - **Often missed initially** (50% misdiagnosed at first presentation) - Patient unable to externally rotate the arm - Arm typically held in internal rotation - Specific imaging views needed (axillary view, scapular Y) **Inferior Dislocation (Luxatio Erecta, Rare):** - Humeral head displaced downward - Patient presents with arm held overhead - Associated with high-energy trauma - Often associated with neurovascular injury **First-Time vs Recurrent:** **First-Time Dislocation:** - Usually traumatic - Often associated with structural damage: - **Bankart lesion** — labral tear at the anterior-inferior glenoid (80-90% of anterior dislocations) - **Hill-Sachs lesion** — compression fracture of the humeral head (30-50%) - **Capsular tear** — ligamentous damage - **Rotator cuff tear** — more common in older patients (>40) - **Neurological injury** — axillary nerve palsy (5-30%) - **Vascular injury** — rare but serious (<1%) **Recurrent Dislocations:** - May occur with progressively less trauma - Sometimes "atraumatic" recurrent - Associated with anatomic predisposition - Each dislocation may cause additional damage **Predictors of Recurrence:** - **Age <20**: 80-90% recurrence rate - **Age 20-30**: 60-70% recurrence - **Age 30-40**: 20-30% recurrence - **Age 40+**: <10% recurrence - Larger Bankart lesions - Hill-Sachs lesion >25% of humeral head - Failure of conservative treatment - High-demand sports

## Root Causes **Shoulder dislocation results from forces exceeding the shoulder's stabilizing capacity:** **Common Mechanisms:** *Traumatic Anterior:* - **Fall on outstretched hand** with shoulder abducted/externally rotated - **Direct blow** to shoulder from behind - **Football tackle position** — arm extended forward - **Skiing/snowboarding falls** - **Hockey/rugby contact** - **Throwing motion** with extreme positioning *Traumatic Posterior:* - **Seizures** (epilepsy, ECT) - **Electrocution** - **Direct blow** to front of shoulder - **Fall onto adducted arm** *Atraumatic Recurrent:* - **Habitual dislocators** (voluntary or involuntary) - **Multidirectional instability** - **Joint hypermobility** - **Previous dislocation** with persistent instability **Risk Factors:** *Modifiable:* - **Inadequate shoulder strength** - **Sport-specific risk** (contact sports without proper conditioning) - **Postural issues** - **Failure to address previous instability** *Non-Modifiable:* - **Age <25** (peak first-dislocation age) - **Male sex** (2-3x risk) - **Joint hypermobility** (Ehlers-Danlos syndrome, generalized laxity) - **Family history** (genetic predisposition) - **Anatomic factors** (shallow glenoid, smaller labrum) *Activity-Related:* - **Contact sports**: football, hockey, rugby, lacrosse - **Throwing sports**: baseball, tennis, volleyball - **Skiing/snowboarding** (falls) - **Military activities** - **Overhead occupations** **Why Young Athletes Have Such High Recurrence:** - More demanding physical activities - Less time for healing/rehabilitation - Structural damage from first dislocation persists - Bankart and Hill-Sachs lesions create predisposition - Aggressive return to sport - Loose tissue characteristics - More plays per season to reinjure - Insufficient strength to compensate

## Acute Management **Immediate priorities: pain control, neurological assessment, prompt reduction** **Pre-Reduction:** - **Neurological examination** — assess axillary, radial, ulnar nerve function - **Vascular check** — pulses, sensation, temperature - **Pain control** — narcotics, intra-articular lidocaine, sedation if needed - **X-ray BEFORE reduction** — confirm dislocation, rule out fracture - **Document baseline neurovascular status** **Reduction Procedure:** - **Multiple effective techniques** available - **Stimson technique** — gentle, gravity-assisted - **Milch technique** — minimal force - **Scapular manipulation** — preferred by many emergency physicians - **Generally not requiring force** if performed correctly - Procedural sedation often used - Some patients reduce with minimal manipulation under analgesia **Post-Reduction:** - **X-ray to confirm reduction** - **Repeat neurovascular exam** - **Sling application** for immobilization - **Pain management** with NSAIDs, acetaminophen - **Plan for follow-up** ## Subsequent Treatment **Immobilization Phase (1-3 Weeks):** - **Sling immobilization** — debated optimal duration - **External rotation immobilization** may reduce recurrence in some studies - **Standard internal rotation sling** most common - Goal: capsular and labral healing in shortened position **Rehabilitation Phase (3-6 Weeks):** - **Phase 1**: Pain-free passive range of motion - **Phase 2**: Active range of motion progression - **Phase 3**: Strengthening (rotator cuff, scapular stabilizers, deltoid) - **Phase 4**: Sport-specific or activity-specific training **Return to Activity (4-12 Weeks):** - **Full range of motion** without apprehension - **Strength symmetry** (≥90%) - **Sport-specific drills** completed - **Activity-specific demands** addressed - **Gradual progression** to full activity ## Surgical Treatment **Indications:** *First-Time Dislocation:* - High-demand young athletes (<25, contact sport) - Large Bankart lesion - Significant Hill-Sachs lesion (>25% of humeral head) - Bone loss >15-20% of glenoid - Failed conservative treatment *Recurrent Dislocations:* - 2+ dislocations - Recurring instability - Career-ending implications for athletes - Progressive structural damage **Surgical Procedures:** *Arthroscopic Bankart Repair:* - Most common procedure - Repairs the torn labrum - Re-establishes anatomic stability - 80-90% success rate - 4-6 month recovery for sport *Open Bankart Repair:* - For complex cases - More secure repair in some situations - Slightly higher success rate - Larger scar *Latarjet Procedure:* - **For significant bone loss** (>15-20% glenoid) - Transfer of coracoid bone to glenoid - Creates bone block + dynamic stability - Very low recurrence (1-5%) - More complex surgery - 6-9 month recovery *Remplissage:* - **For large Hill-Sachs lesion** - Often combined with Bankart repair - Fills the humeral head defect **Post-Surgical Recovery:** - Sling 4-6 weeks - Passive ROM 0-6 weeks - Active ROM 6-12 weeks - Strengthening 3-6 months - Return to sport 4-6 months (some procedures 6-9 months) - Re-dislocation rate after surgery: 5-15% ## Critical Treatment Decisions **Conservative vs Surgical for First-Time Dislocation:** This is one of the most debated topics in orthopedic surgery. Current evidence suggests: *Strong case for surgery:* - Young (<25), male, contact sport athlete - Bankart lesion present - Significant bone loss - High activity level *Reasonable for conservative trial:* - Older patients (>30) - Lower demand activities - Smaller structural damage - Patient preference **Best Outcomes Come From:** - Appropriate procedure selection - Adequate immobilization period - Comprehensive rehabilitation - Realistic return-to-sport timeline - Address bone loss with appropriate procedure ## Prevention Programs **Sport-Specific:** - **Football**: Proper tackling technique - **Hockey**: Shoulder protection equipment - **Rugby**: Tackle/contact instruction - **Skiing**: Falling technique **General Prevention:** - **Rotator cuff strengthening** - **Scapular stabilizer strengthening** - **Sport-specific conditioning** - **Address joint laxity** with strengthening - **Avoid risky positions** when possible - **Family screening** if hereditary predisposition **For Patients with Previous Dislocation:** - Comprehensive shoulder rehabilitation - Consider surgical stabilization in young athletes - Activity modifications if needed - Bracing for return to contact sports