Anterior shoulder dislocation

Case contributed by Dr David Carroll

Presentation

Patient presents after a seizure with right shoulder pain. Holding affected extremity in slight abduction.

Patient Data

Age: 50 years
Gender: Male

Point of care ultrasound

Ultrasound

Posterior view of the glenohumeral joint. Transducer parallel to plane of scapular spine with the probe marker lateral.

Humeral head displaced anteriorly into the far field, loss of apposition with the glenoid, anechoic space filling glenohumeral joint consistent with effusion and (likely) hemarthrosis. Suggestive of anterior shoulder dislocation. 

X-ray

Radiographs demonstrate anteroinferior dislocation of the humeral head from the glenoid with a greater tuberosity fracture.

Post-reduction

Ultrasound

Interval reduction of humeral head into apposition with the glenoid. Significant cortical irregularity of the posterolateral humeral head consistent with the fracture visualized on radiography.

Post-reduction

X-ray

Humeral head articulation is restored with glenoid. Aforementioned fracture of the greater tuberosity redemonstrated.

There is a severely comminuted, mildly displaced fracture involving the lateral humeral head and greater tuberosity. Humeral head in appropriate apposition to glenoid, with a small joint effusion appreciated. There is a fracture of the anteroinferior glenoid rim, with a medial and anterior displacement of a fragment measuring 2.0 x 0.5 x 0.5 cm.

No abnormalities of the clavicle or acromioclavicular joint. No overlying soft tissue abnormalities. There are no foreign bodies or subcutaneous air.

Case Discussion

The glenohumeral joint is the most commonly dislocated joint in the body, the vast majority of which are anterior dislocations. Mechanism of injury typically involves an extended and abducted arm incurring a posteriorly directed force 1. Patients typically present with pain and a decreased range of motion; on exam "squaring" of the shoulder may be observed due to a conspicuous acromion process, as well as the patient holding their arm in slight abduction 2.

A screening exam with point of care ultrasound may be performed to evaluate for the presence of, and assist in the management of, suspected dislocations. With the transducer at the posterior aspect of the shoulder, parallel to the scapular spine, the humeral head may be visualized laterally as a curvilinear opacity with its medial margins in close apposition to the adjacent glenoid fossa 3. Maintenance of glenohumeral articulation through full, dynamic range of motion through internal and external rotation is inconsistent with dislocation.

Anterior dislocation will manifest as displacement of the humeral head away from the probe, into the far field, while posterior dislocations will demonstrate displacement toward the probe. Ultrasound may be used after the appropriate reduction maneuver and immobilization to confirm preliminary success, which should be confirmed with standard radiography 4

Ultrasound may also be used to supplement other conventional imaging modalities in the detection of associated conditions, such as:

  • greater tuberosity fractures 4
    • discontinuity or "step-off" of the usually smooth cortical surface 
  • glenohumeral joint effusions
    • hemarthrosis nearly ubiquitous in traumatic dislocations 

 

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