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In shoulder (glenohumeral) dislocations, the humeral head separates from the glenoid fossa; displacement is almost always anterior.
Shoulder dislocations account for about half of major joint dislocations.
Shoulder dislocations may be
Shoulder dislocations are anterior in ≥ 95% of patients; the mechanism is abduction and external rotation. Associated injuries can include brachial plexus injuries, rotator cuff tears (particularly in elderly patients), fracture of the greater tuberosity, and axillary nerve injury. Shoulder instability and thus recurrent dislocation are common in patients < 30 yr.
The acromion is prominent, and the elbow is held slightly out from the side; the humeral head is displaced anteriorly and inferiorly and cannot be palpated in its usual position. Patients are unwilling to move the arm. They may have motor and sensory deficits (eg, if the axillary nerve is injured, decreased sensation over the deltoid).
True anteroposterior (AP) and axillary x-rays are diagnostic for anterior dislocations, showing the humeral head outside the glenoid fossa.
Treatment is usually closed reduction using local anesthesia (intra-articular block) or conscious sedation. Commonly used methods of reduction include
Traction-countertraction (see Figure: Traction-countertraction technique for reducing anterior shoulder dislocations.)
External rotation (eg, Hennepin technique—see Figure: Hennepin technique for reducing anterior shoulder dislocations.)
Cunningham (massage) technique
Many techniques (eg, Hennepin, scapular manipulation, Cunningham) can be done without sedation, but they require time for muscles affected by spasm to adequately relax; patients must be able to focusing their attention on relaxation.
After reduction, the joint is immobilized immediately with a sling and swathe (see Figure: Joint immobilization as acute treatment: Some commonly used techniques.).
Traction-countertraction technique for reducing anterior shoulder dislocations.
Hennepin technique (external rotation) can be done with the patient supine or seated. The dislocated arm is adducted with the elbow held at 90°. The arm is then externally rotated slowly (eg, over 5 to 10 min) to allow time for muscle spasms to resolve. Reduction commonly occurs at 70 to 110° of external rotation. This technique is effective in about 80 to 90% of cases.
Hennepin technique for reducing anterior shoulder dislocations.
The practitioner adducts the dislocated arm with the elbow held at 90°. The arm is then externally rotated slowly (eg, over 5 to 10 min) to allow time for muscle spasms to resolve. Reduction commonly occurs at 70 to 110° of external rotation.
Scapular manipulation can be done with the patient in upright or prone. The practitioner flexes the patient's elbow 90° and slowly externally rotates the arm. An assistant applies gentle traction on the arm. The practitioner then rotates the scapula so that the inferior tip moves medially, toward the spine. Scapular manipulation can be used with other techniques (eg, Stimson technique).
The Cunningham technique involves massage of the muscles around the glenohumeral joint while the patient is sitting. The practitioner does the following:
Sits facing and just to the side of the patient
Puts the patient’s hand on the practitioner's shoulder, keeping the patient's elbow flexed
Puts the practitioner's hand in the depression in the bend of the patient's elbow (antecubital fossa) and holds the dislocated arm in place
Massages the biceps, mid-deltoid, and trapezius to relax muscle spasms
Instructs the patient to try to relax rather than tense up if the shoulder feels as if it is moving (relaxation is crucial to reduction using this technique)
Instructs the patient to sit up straight (no slouching forward or to the side) and to shrug the shoulders back, trying to make the upper ends of the right and left scapula touch each other
The shoulder slips back into place within minutes.
The Stimson technique (also called the dangling weights technique) is done less commonly. It is done with the patient prone and the affected extremity hanging over the side of a bed. Weights are attached to the wrist. After about 30 min, the muscle spasm usually relaxes enough to allow the humeral head to reduce. Because the patient is prone, conscious sedation is not recommended. This position may be too uncomfortable for pregnant patients and extremely obese patients. This technique can also be used with scapular manipulation; the practitioner applies scapular manipulation while the patient is prone. This approach shortens the time needed for shoulder to relocate.
Occasionally, dislocations are posterior—a commonly missed injury (see Table: Examination for Some Commonly Missed Injuries). It is classically caused by seizures, electric shock, or electroconvulsive therapy done without muscle relaxants.
Deformity may not be obvious. The arm is held adducted and internally rotated. Typically, when the elbow is flexed, passive external rotation is impossible. If such rotation is impossible, an AP shoulder x-ray should be taken. If it shows no obvious fracture or dislocation, posterior shoulder dislocation should be considered. A clue to the diagnosis on the AP view is the light bulb or ice cream cone sign; the humeral head is internally rotated, and the tuberosities do not project laterally, making the humeral head appear circular.
The axillary view or trans-scapular Y view is diagnostic.
Reduction is often possible using longitudinal traction (as with the traction-countertraction technique).
Inferior dislocations (luxatio erecta) are rare and usually clinically obvious; patients hold their arm over their head (ie, abducted to almost 180°), usually with the forearm resting on the head. The arm is shortened; the humeral head is often palpable in the axilla. The joint capsule is disrupted, and the rotator cuff may be torn. The brachial artery is injured in < 5% of cases. The axillary nerve or another nerve is usually damaged, but deficits often resolve after reduction.
X-rays are diagnostic.
Reduction is done using traction-countertraction of the abducted arm. Closed reduction is usually successful unless there is a buttonhole deformity (humeral head is trapped in a tear of the inferior capsule); in such cases, open reduction is required.
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