What are the typical presentation, management, and potential complications of an anterior shoulder dislocation?

Anterior Shoulder Dislocation: Clinical Presentation, Management, and Complications

Typical Presentation

An 18-year-old woman who fell on her outstretched arm with subsequent severe pain and limited range of motion most likely has an anterior shoulder dislocation, which accounts for the vast majority of glenohumeral dislocations and requires immediate radiographic confirmation before reduction. 1

Key Clinical Features

• Mechanism of injury: Fall on outstretched arm with the shoulder in abduction and external rotation 2
• Physical findings: Severe pain, inability to move the shoulder, visible deformity with loss of normal shoulder contour, and the arm typically held in slight abduction and external rotation 2
• Age and sex distribution: Young, active individuals are most commonly affected, with males having higher incidence than females 2, 3

Diagnostic Approach

Initial Imaging (Pre-Reduction)

Radiography must be obtained before attempting reduction to confirm the dislocation and identify associated fractures. 1

• Required views: Anteroposterior (AP) in internal and external rotation PLUS an axillary or scapula-Y view 1
• Critical pitfall: AP views alone miss posterior dislocations in over 60% of cases; the axillary or scapula-Y view is mandatory to avoid misclassification 1
• Associated fractures to identify: Hill-Sachs deformity (posterolateral humeral head compression fracture) and bony Bankart lesion (anterior glenoid rim fracture) 1

Post-Reduction Imaging

• Mandatory post-reduction radiographs to confirm successful reduction and evaluate for fractures that may have been obscured by the dislocation 1, 4
• Neurovascular assessment is critical following reduction, particularly evaluating axillary nerve function and vascular integrity 1, 4

Advanced Imaging Considerations

• For this 18-year-old: Given the high recurrence risk in young patients, consider MR arthrography (gold standard, rated 9/9 appropriateness) or non-contrast MRI (rated 7/9) to evaluate for labral tears, capsular injuries, and bone loss that predict recurrence 5, 4, 6
• CT angiography if vascular compromise is suspected, especially with associated proximal humeral fractures 1, 4

Management

Immediate Reduction

• Reduction should be performed promptly as delays increase the risk of neurovascular complications 1
• Multiple reduction techniques are available; newer techniques like "Han's technique" can be performed without anesthesia or sedation with high success rates (95%) and low pain scores (VAS 1.83 ± 0.83) 7
• Procedural sedation options if needed: Propofol or etomidate with opioid analgesia are effective; etomidate provides shorter sedation duration (10 minutes) compared to midazolam (23 minutes) for shoulder reduction 5

Post-Reduction Immobilization

• Conservative approach: 1-3 weeks of immobilization in internal rotation, followed by rehabilitation 3
• Critical consideration for this patient: Age is the most important predictor of recurrence; studies support that age and activity level are more important than length of immobilization 3, 8

Surgical vs. Conservative Management

For patients aged 21-30 years with primary anterior shoulder dislocations, early surgical intervention is strongly supported by the majority of studies due to the particularly high recurrence rate in this age group. 3

• Recurrence rates: Young, active individuals have the highest recurrence rates following conservative management 2, 3
• Surgical timing: Early surgical intervention is preferred as delayed surgery is associated with progressive labro-ligamentous injury 6
• Conservative management: Reserved for older patients or those with lower activity demands 3, 8

Potential Complications

Immediate Complications

• Neurovascular injury: Axillary nerve injury is most common; axillary artery injury can occur, especially with proximal humeral fractures 1, 4
• Associated fractures: Large tubercle fractures (27% in one series) and glenoid rim fractures 7
• Rotator cuff tears: More common in older patients but can occur in younger individuals, particularly with traumatic mechanisms 4, 9

Long-Term Complications

• Recurrent instability: The most significant long-term complication, particularly in young, active patients 2, 3
• Progressive glenoid bone loss: Found in up to 10% of patients with recurrent instability; significant bone loss (>20%) requires specialized surgical procedures like the Latarjet procedure 6
• Post-traumatic arthritis: Up to one-third of patients develop long-term shoulder arthritis, even after a single dislocation episode 2
• Chronic pain and dysfunction: Even patients with single episodes may develop long-term sequelae 2

Critical Pitfalls to Avoid

• Never attempt reduction without radiographic confirmation as this could worsen fracture-dislocations 1
• Do not rely on AP views alone; failure to obtain axillary or scapula-Y views leads to missed diagnoses 1
• Do not overlook associated rotator cuff tears, especially in patients over 40 years or with high-energy trauma 4, 9
• Do not delay reduction as this increases neurovascular complications 1
• For young patients (18-30 years): Do not assume conservative management will suffice; discuss early surgical options given the high recurrence risk in this age group 3