HWN Suggests

Posterior Shoulder Dislocation: Radiographic Evidence

You immediately suspect an anterior shoulder dislocation and gleefully attempt a Cunningham reduction while taking your history. The patient notes a one-week history of increasing left shoulder instability. His past medical history is significant for previous dislocations of both shoulders. He is otherwise well and takes no medications. He awoke with the shoulder discomfort and came in straight away. Unfortunately, your reduction is not successful and you start thinking about that energy drink again. You slink off to order a series of shoulder films.

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 Commonly Missed or Mismanaged Shoulder Injuries – Approach and Glenohumeral Dislocations

External rotation technique In sitting position, downward traction on proximal forearm and external rotation by one provider (similar to reduction of anterior glenohumeral dislocation) plus push on humeral head from behind the patient by a second provider.

Articles of Interest

An Easily Missed Shoulder Injury

Reduction technique: Traction-countertraction should be applied on the adducted and internally rotated arm, and posterior-to-anterior pressure should be applied on the humeral head. You may also create leverage by applying lateral pressure to the medial aspect of the proximal humerus to dislodge an impacted humeral head.

Bilateral posterior shoulder dislocation: the importance of the axillary radiographic view

Whilst posterior shoulder dislocation is rare, it remains a frequently missed diagnosis. In all patients with a history of seizure, electrocution or similar trauma, where external rotation of the shoulder is limited, we recommend that an axillary or modified axillary view be added to the standard two radiographic shoulder views as routine protocol, to avoid missing a posterior dislocation.

Clinical Image Case: Triple “E” Syndrome

Shoulder dislocations account for approximately 50% of joint dislocations, with anterior dislocation making up 95% of shoulder dislocations, posterior shoulder dislocations accounting for ~4%, and the remaining ~0.5% of shoulder dislocations due to inferior dislocations (luxatio erecta). When posterior shoulder dislocation does occur, they are usually secondary to seizure, electric shock, or severe trauma.

EM@3AM: Posterior Shoulder Dislocation

Mechanics are similar to traction-countertraction technique used in anterior dislocation. With patient supine, apply inferior and posterior traction to long axis of humerus. Have an assistant applying direct pressure to posterior humeral head and another providing countertraction.

Irreducible Traumatic Posterior Shoulder Dislocation

Posterior shoulder dislocations are rare and represent only 2% of all shoulder dislocations. Posterior shoulder dislocations are missed on initial diagnosis in more than 60% of cases.1 Posterior shoulder dislocations result from axial loading of the adducted and internally rotated shoulder, violent muscle contractions (resulting from seizures or electrocution), a direct posterior force applied to the anterior shoulder.

Neil Cunningham Technique

Adduction procedure

Posterior Shoulder Dislocation

Posterior dislocations of the shoulder are uncommon, making up less than 5% of all shoulder dislocations. They can occur from an anterior blow or from violent muscle contractions during seizures. On exam, the patient will have the arm adducted and internally rotated and will be unable to externally rotate it. There will also be anterior flattening of the shoulder with a posterior prominence.

Posterior Shoulder Dislocation Reduction

Posterior shoulder dislocations are uncommon and account for about 4% of shoulder dislocations. In this video we demonstrate this injury and its reduction. We also review a common associated injury, the reverse Hill-Sachs deformity.

Resources

Brown Emergency Medicine

Posterior dislocations of the shoulder are uncommon, making up less than 5% of all shoulder dislocations. They can occur from an anterior blow or from violent muscle contractions during seizures. On exam, the patient will have the arm adducted and internally rotated and will be unable to externally rotate it. There will also be anterior flattening of the shoulder with a posterior prominence.

Life in the Fastlane

Posterior shoulder dislocations make up a small minority of total shoulder dislocation cases, accounting for 2-4% of presentations. However because of a low level of clinical suspicion and insufficient imaging, they are often missed. Approximately half of posterior shoulder dislocations go undiagnosed on initial presentation.

EBM Consult

Closed reduction technique (if not contraindicated): gentle, prolonged axial traction along the humerus while applying gentle anteriorly directed pressure to get the humeral head over the glenoid rim.

StatPearls

The shoulder girdle is a complex articulation connecting the upper extremity to the axial skeleton. The glenohumeral joint of the shoulder is the most commonly dislocated joint in the body and accounts for approximately 50% of all major dislocations seen in the emergency department. Posterior shoulder dislocations account for about 2% to 5% of all shoulder dislocations. Recurrent posterior dislocations occur in 30% of patients and predispose the joint to degenerative changes. Dislocations in a posterior direction can be difficult to diagnose, so a high index of suspicion should be maintained when the typical history and findings on the physical exam are present.

UMEM Educational Pearls

Best way to make the diagnosis --- suspect it and get an axillary view.