Shoulder radiograph (an approach)

Shoulder radiographs are common films to see in the Emergency Department, especially during the weekend after sporting events.

Systematic review

Choosing a search strategy and utilizing it consistently is a helpful method to overcome common errors seen in diagnostic radiology. The order in which you interpret the radiograph is personal preference. A recommended systematic checklist for reviewing musculoskeletal exams is: soft tissue areas, cortical margins, trabecular patterns,bony alignment, joint congruency, and review areas. Review the entire radiograph,regardless of perceived difficulty. Upon identifying an abnormality, do not cease the review, put it to the side and ensure to complete the checklist.  

Soft tissue

Assess all soft tissue structure for any associated or incidental soft tissue signs 

Bony cortex

• cortex should be smooth
  • humeral head
  • glenoid fossa
  • clavicle
  • body of scapula
• look for fracture fragments
• remember the ribs

Joints and alignment 

Glenohumeral joint

• articular surfaces should be parallel
• the humeral head should be on the glenoid in any other view
• if the humeral head lies under the coracoid process, think anterior shoulder dislocation
• if there is a joint effusion, think humeral head or glenoid fracture

Acromioclavicular joint

• the inferior borders of distal clavicle and acromion should line up
• if there is a step, think ACJ injury
  • acromioclavicular (AC) distance >8 mm: AC ligament rupture
  • coracoclavicular (CC) distance >13 mm: CC ligament rupture

Review areas

Although a majority of your focus may be on the shoulder girdle, be vigilant in inspecting the entire radiograph including the:

• ribs 
• lung (e.g. pneumothorax, Pancoast tumor)
• any bony/soft tissue regions included in the projection

Common pathology

Anterior shoulder dislocation

• 95% of all shoulder dislocations
• young males and the elderly
• forced abduction, external rotation and extension
• humeral head lies anterior, medial and inferior to glenoid fossa
• common associated fractures
  • Hill-Sachs defect
  • Bankart lesion
• more: anterior shoulder dislocation

Clavicle fracture

• up to 10% of all fractures
• predominantly midshaft
• mostly children and the elderly
• fall onto outstretched hand or shoulder
• more: clavicle fracture

Acromioclavicular joint injury

• very common injury
• range from strain to complete joint disruption
• direct blow or fall onto shoulder with adducted arm
• step at AC joint, widening of AC joint and/or increased CC distance
• more: acromioclavicular joint injury

Proximal humeral fracture

• common injury resulting in significant disability
• elderly females: mean age 65 years
• fall on an outstretched arm
• more: proximal humeral fracture

Don't miss

Posterior shoulder dislocation

• less than 5% of glenohumeral dislocations but often overlooked
• common in adults following a seizure or in the elderly
• humeral head forced posteriorly in internal rotation whilst arm is abducted
• classically, the humeral head is rounded on AP - light bulb sign
• associated with anteromedial fracture of humeral head
• more: posterior shoulder dislocation

Shoulder pseudosubluxation

• usually secondary to trauma
• an effusion or hemorrhage into the joint displaces the humeral head inferiorly
• this effusion suggests intra-articular fracture
• do not confuse with dislocation!
• more: shoulder pseudosubluxation

Pancoast tumor

• primary bronchogenic carcinoma arising in lung apex
• account for up to 5% of all bronchogenic cancers
• always review lung parenchyma, ribs and supraclavicular fossa in AP shoulder radiographs
• more: Pancoast tumor