Presentation
Left shoulder pain and limited external rotation after being hit by a car.
Patient Data
Widened glenohumeral joint.
Incongruent joint surfaces.
Humerus internally rotated.
Impaction fracture of the anteromedial aspect of the left humeral head, compatible with reverse Hill-Sachs fracture.
Satisfactory reduction. The humeral head is well-positioned within the glenoid fossa.
Case Discussion
This is a case of posterior dislocation with a reverse Hill-Sachs impaction fracture.
Posterior dislocation is commonly missed and this results in long-term morbidity.
The humeral head is typically perched on the posterior glenoid rim and external rotation is impossible. The lack of an external rotation view should prompt closer examination.
The lateral scapular view shows the posterior displacement in this case and the Grashey view shows the glenoid fossa in profile but not the joint space. Compare this with the post-reduction Grashey view. Standard axial view is usually not possible when the glenohumeral joint is dislocated but half-axial views such as the Wallace view are diagnostic.
The Wallace view is obtained with the patient sitting with their arm in a collar and cuff. The detector is positioned horizontally behind the elbow and the X-ray tube is angled caudally 65 degrees and laterally 15 degrees, with the beam centered on the joint.
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