Laboratory Studies
Laboratory studies are not necessary to diagnose shoulder dislocation injuries.
Imaging Studies
Radiographs
When dealing with shoulder instability, obtaining 2 orthogonal views of the shoulder is imperative.
The author suggests routinely ordering an anteroposterior (AP) view of the shoulder and an axillary lateral view. If an axillary lateral radiography cannot be obtained, then a scapular Y view may be taken in its place. If good radiographs cannot be obtained, order a computed tomography (CT) scan. This study can be performed quickly and is not expensive.
Posterior shoulder dislocations can look like a normal shoulder on the AP view. If an orthogonal view radiograph is not obtained, the diagnosis may be missed.
Magnetic resonance imaging (MRI)
MRI can show damage to ligaments that may be torn with shoulder dislocation. They are better seen with the injection of contrast into the joint before the MRI evaluation. The bony architecture on these studies can also be appreciated.
Patients older than 45 years may also tear the rotator cuff tendons when the shoulder is dislocated. The tendons are less elastic and do not stretch out during the incident and thus tear. Proper diagnosis is necessary to get these patients back to their preinjury status. If the patient is older than 45 years and has marked weakness in the strength testing of the rotator cuff muscles, an MRI is a great tool to assess for tears.
Procedures
The most important treatment of an acute shoulder dislocation is prompt reduction of the glenohumeral joint. [1, 2, 3] Numerous reduction techniques have been described that can be performed after administering an intra-articular injection or after putting the patient under conscious sedation. After determining the direction of the dislocation, the physician must remember that the most important aspect of reduction is relaxation of the shoulder musculature. Once reduction has been accomplished, postreduction radiographs are necessary to verify reduction.
Shoulder reduction techniques are as follows:
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For the more common anterior dislocations, one of the oldest methods of reduction is the Hippocratic method, in which the physician's foot is placed in the patient's axilla while gentle longitudinal traction is applied. Internal or external rotation of the shoulder may facilitate reduction.
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The Stimson technique involves having the patient lie prone on an examining table, allowing the affected arm to hang off the bed. Again, longitudinal traction and internal or external rotation are applied to the arm. Weights can also be added to the patient's wrist to facilitate reduction.
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The Milch maneuver is one in which abduction and external rotation are applied to the affected extremity while the physician's thumb disengages the humeral head. This technique can also be attempted with the patient in the prone position.
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Finally, one of the simplest maneuvers is passive forward elevation of the arm while the physician maneuvers the humeral head with the opposite hand.
Differentiating a posterior from an anterior dislocation is important, because the reduction maneuvers differ. If reduction cannot be achieved with the patient under conscious sedation, general anesthesia may be needed for adequate relaxation. The patient should be in the supine position. The affected arm should be adducted with the application of gentle traction. The humeral head should be maneuvered anteriorly by the examiner's hand. The arm should not be rotated externally because the presence of a humeral fracture is possible.
Related Medscape Reference topics include Joint Reduction, Shoulder Dislocation, Anterior.
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Anterior dislocation.
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Normal shoulder.
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Shoulder dislocation, Part 1.
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Shoulder dislocation, Part 2.
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Shoulder dislocation, Part 3.
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Shoulder dislocation, Part 4.
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Shoulder dislocation, Part 5.
