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A 65-year-old woman presented to the ED with shoulder pain after falling down. She was pushed and fell onto her outstretched right arm and shoulder. There were no other injuries.

On examination, her vital signs were normal. She was in moderate distress and resisted any attempt to move her shoulder, which had been immobilized in a sling by the ambulance crew in the field. There was loss of the normal shoulder contour with a prominent step-off deformity at the acromion and a palpable concavity of the deltoid region. Neurovascular function was intact.

Parenteral analgesia was administered and radiographs were obtained (Figure 1). (A metal clip from the shoulder sling is seen on the AP view.)

  • Why obtain x-rays on a patient with a shoulder dislocation that can be diagnosed by clinical examination?
  • How would you reduce this shoulder dislocation?
  • What are the significant findings on these radiographs?

The standard AP view of the shoulder, in conjunction with the findings on physical examination, is usually sufficient to diagnose an anterior dislocation (Figure 2A).

Figure 2

Anterior shoulder dislocation.

(A) AP view: The humeral head is in external rotation (greater tuberosity is lateral, arrow) and in a subcoracoid location. Asterisk = coracoid process.

(B) Scapular Y view: Interpretation of this view can be difficult when it is slightly oblique and overlying soft tissues obscure the image, as in this patient. The humeral head overlies the ribs (arrowheads). Arrow = glenoid fossa.

(C) Post-reduction view: There is a large linear deformity (arrowheads) representing an impacted fracture of the humeral head (Hill-Sachs deformity). This was not evident on the initial radiographs. This common fracture does not alter emergency management. If large, it predisposes to recurrent dislocation and may need surgical repair.

(D) Clinical findings include an abrupt step-off deformity due to a prominent acromion (arrow), palpably empty glenoid fossa, and the arm held in external rotation and abduction.

[D from: Knoop KJ, Stack LB, Storrow AB: Atlas of Emergency Medicine, 2nd ed., McGraw-Hill, 2002, with permission.]

Although an AP radiograph does not allow direct determination of whether the dislocated humeral head is anterior or posterior to the glenoid fossa, anterior dislocation can be surmised by making two observations. First, with an anterior dislocation, displacement of the humeral head is much greater than is possible with a ...

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