What are the typical physical exam findings and management of a patient with a shoulder dislocation?

Physical Examination Findings in Shoulder Dislocation

The physical examination of a shoulder dislocation reveals distinct findings based on the direction of displacement: anterior dislocations present with the arm held in abduction and external rotation with loss of normal shoulder contour, while posterior dislocations show fixed internal rotation with preserved external contour—the latter being missed in over 60% of cases initially due to the arm's deceptively normal adducted position. 1, 2, 3

Anterior Shoulder Dislocation (95% of cases)

Key Physical Findings

• Arm position: The affected arm is held in slight abduction (typically 20-30 degrees) and external rotation, with the patient unable to bring the arm to their side 1
• Shoulder contour: Loss of normal rounded deltoid contour with visible or palpable anterior fullness from the displaced humeral head 1
• Acromion prominence: The acromion appears abnormally prominent, creating a "squared-off" shoulder appearance 1
• Palpable humeral head: The humeral head may be palpable anteriorly, often in the subcoracoid position 1

Neurovascular Assessment (Critical)

• Axillary nerve: Most commonly injured nerve (present in 5.4-55% of dislocations), assessed by testing sensation over the lateral deltoid ("regimental badge" area) and deltoid muscle contraction 1, 4
• Brachial plexus: Multiple nerve involvement occurs more frequently than isolated mononeuropathies, particularly in elderly women from simple falls and young men from high-energy trauma 4
• Vascular injury: Axillary artery injury must be assessed, especially critical with associated proximal humeral fractures—check distal pulses, capillary refill, and limb temperature 5, 1

Posterior Shoulder Dislocation (2-4% of cases)

Key Physical Findings (Often Missed)

• Arm position: The arm is held in adduction and fixed internal rotation—this appears deceptively normal, contributing to the >60% initial misdiagnosis rate 2, 3, 6
• Fixed internal rotation: The patient cannot externally rotate the arm; this is the most consistent and reliable finding 3
• Scapular movement: Characteristic abnormal scapular movement occurs with attempted abduction of the upper extremity 3
• Posterior fullness: Subtle posterior prominence may be present, though the shoulder contour often appears relatively normal from the front 3, 6
• Coracoid prominence: The coracoid process may be more prominent anteriorly 3

Age-Specific Considerations

Elderly Patients (>60 years)

• Rotator cuff tears: Significantly more likely in older patients with shoulder dislocation compared to younger patients 7, 5, 1
• Clinical signs: Look for weakness in external rotation (infraspinatus/teres minor), abduction (supraspinatus), or internal rotation (subscapularis) suggesting associated rotator cuff pathology 5
• Lower energy mechanism: Often occurs from simple falls rather than high-energy trauma 4

Younger Patients (<35 years)

• Labral pathology: More likely to have labroligamentous injury and persistent instability after dislocation 7
• Recurrence risk: Higher risk of recurrent instability requiring evaluation for capsular injuries and bone loss 1

Critical Pitfalls to Avoid

• Never rely on AP radiographs alone: Posterior dislocations are missed in over 60% of cases without axillary or scapula-Y views 1, 2, 3
• Never attempt reduction without radiographic confirmation: This could worsen occult fracture-dislocations, particularly Hill-Sachs deformities or bony Bankart lesions 1, 2
• Do not overlook neurovascular assessment: Document axillary nerve function and vascular status before AND after reduction, as delays in identifying complications worsen outcomes 5, 1, 4
• Do not miss associated rotator cuff tears in elderly patients: Failure to identify these leads to persistent symptoms and secondary osteoarthritis 5, 1
• Do not delay reduction: Prolonged dislocation increases neurovascular complications and makes reduction more difficult 1, 4

Mandatory Imaging Protocol

Pre-Reduction

• Required views: Anteroposterior (AP) in internal and external rotation PLUS axillary or scapula-Y view 7, 1, 2
• Purpose: Confirm dislocation direction and identify associated fractures (Hill-Sachs deformity, bony Bankart lesion) before manipulation 1, 2

Post-Reduction

• Mandatory repeat radiographs: Confirm successful reduction and evaluate for fractures that may have been obscured by the dislocation 5, 1, 2
• Repeat neurovascular exam: Document axillary nerve and vascular integrity following reduction 1, 2

Advanced Imaging Indications

• MR arthrography: Gold standard for evaluating labral tears, capsular injuries, and rotator cuff pathology in subacute or recurrent instability (appropriateness rating 9/9) 7, 5, 1
• MRI without contrast: Preferred in acute dislocation settings when MR arthrography unavailable (appropriateness rating 7/9) 7, 5
• CT angiography: Indicated if vascular compromise suspected, especially with proximal humeral fractures 1, 2