What are the signs and symptoms of a dislocated shoulder and which clinical tests are recommended?

Signs and Symptoms of Shoulder Dislocation

A dislocated shoulder presents with severe pain, visible deformity, loss of normal shoulder contour with anterior flatness and posterior fullness (in posterior dislocations), and marked restriction of external rotation and abduction—obtain a standard 3-view radiograph series (AP in internal/external rotation plus axillary or scapula-Y view) immediately to confirm the diagnosis and identify associated fractures. 1

Clinical Presentation

Key Signs and Symptoms

Anterior Dislocation (>95% of cases):

• Severe shoulder pain following forceful abduction and external rotation injury
• Visible shoulder deformity with loss of normal rounded contour
• Arm held in slight abduction and external rotation
• Inability to move the shoulder, particularly loss of external rotation
• Palpable humeral head anteriorly (if not reduced)
• Possible neurovascular compromise (check axillary nerve and distal pulses)

Posterior Dislocation (often missed >60% of the time initially):

• History of seizure, electroshock, or fall onto flexed/adducted arm 2
• Subtle posterior fullness of the shoulder
• Anterior flatness compared to contralateral side
• Marked loss of external rotation and abduction (key finding)
• Arm held in internal rotation and adduction
• Requires high index of suspicion—compare carefully to unaffected shoulder 2

Critical Pitfall

Posterior dislocations are frequently missed because they appear less dramatic on examination and can be overlooked on AP radiographs alone—always obtain axillary or scapula-Y views, as these are vital for detecting glenohumeral malalignment that may be misclassified on AP views alone. 1

Physical Examination Tests for Instability

For Anterior Instability (Highest Yield)

Apprehension Test with Variations:

• Apprehension sign: Likelihood ratio 8-100 for anterior instability 3
• Relocation test: Apply posterior force to humeral head while in apprehension position—relief of symptoms confirms instability
• Release test: Remove posterior pressure—return of apprehension confirms diagnosis
• These tests combined provide excellent specificity when positive 4, 3

Load and Shift Test:

• When positive, extremely predictive (likelihood ratio >80) 3
• However, poor at ruling out posterior/inferior instability when negative

For Multidirectional Instability

Sulcus Sign:

• Pull arm inferiorly while observing space beneath acromion
• Sulcus ≥2 cm is highly predictive of multidirectional instability (likelihood ratio 9) 3, 5

For Superior Labral Pathology

O'Brien's Sign:

• Likelihood ratio 3-50 for superior labral detachment 3, 5

Important Considerations

• Apprehension tests have reasonable inter-examiner reliability (ICC 0.5-0.7) 3
• Distinguish laxity from instability—laxity without symptoms does not equal pathologic instability 4
• Overhead athletes may present with subtle subluxation rather than frank dislocation 6

Recommended Imaging

Initial Imaging: Radiography (Always First)

Standard trauma series must include at least 3 views: 7, 1

• AP views in internal and external rotation
• Axillary OR scapula-Y view (mandatory—not optional)
• Perform upright when possible (supine films can underrepresent malalignment) 1

Rationale: Radiography identifies displaced fractures and shoulder malalignment—the two primary concerns requiring immediate management. 1

Advanced Imaging After Initial Radiographs

If dislocation/instability confirmed on radiographs:

• MRI shoulder without IV contrast is usually appropriate as next study 7
• In acute setting, post-traumatic joint effusion/hemarthrosis provides natural contrast for soft tissue visualization
• MRI effectively diagnoses labral tears, rotator cuff injuries, glenohumeral ligament damage, and bone marrow edema 7, 1

Alternative/Additional Studies:

• CT without contrast: Use when MRI assessment of bone loss is limited or MRI contraindicated 7
• MR arthrography: Gold standard for chronic/recurrent instability but unnecessary acutely due to natural joint effusion 1
• Ultrasound: Can diagnose dislocations with 100% sensitivity/specificity using posterior approach, significantly faster than radiography (median 43 minutes faster from triage), but limited for fracture detection beyond humeral shaft 8

Age-Specific Considerations

• Younger patients: More likely to have labroligamentous injury and recurrent instability 1
• Older patients: Higher risk of associated rotator cuff tears with dislocation 1

Clinical Pearls

• Never rely on AP view alone—60% of posterior dislocations are initially missed without proper orthogonal views 2
• Check neurovascular status immediately, particularly axillary nerve function
• Document comparison to contralateral shoulder for subtle findings
• In overhead athletes, consider subtle subluxation events rather than frank dislocation 6
• Glenoid bone loss and morphology significantly affect recurrence risk 1