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The combination of abduction, extension, and external rotation with sufficient force will cause an anterior dislocation. There are multiple types of anterior glenohumeral dislocations (Figure 271-7). These include subcoracoid, which is the most common; subglenoid; subclavicular; and the very rare intrathoracic dislocation.
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Prereduction radiographs are advisable when there has been significant trauma, unless time is crucial because circulation is threatened. Radiographs are needed because dislocations and fracture-dislocations may have a similar appearance on physical examination, but the techniques used to treat them may be very different. Shoulder dislocations or subluxations combined with proximal humerus fractures generally require orthopedic consultation and may need operative repair. Shoulder dislocations with associated proximal humerus fracture increase with age. Through the third decade, fracture-dislocations occurred less than 1% of the time. This percentage rises with each decade of life.24 Postreduction radiographs are valuable for confirming the success of joint reduction, as well as for providing documentation, in the event the joint redislocates after the patient is discharged from the ED.
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There is an expenditure of time, money, and radiation associated with pre- and postreduction films; however, there is currently no validated clinician decision rule that allows safe elimination of prereduction films after injury.25 In clinical practice, films are sometimes omitted in patients with a history of multiple recurrent dislocations of the shoulder who present with history, signs, and symptoms typical of another recurrence in the absence of significant trauma.23,25
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The three main categories of reduction techniques are traction, leverage, and scapular manipulation.26,27,28,29 Success rates are between 70% and 96% regardless of technique. It is essential to provide appropriate systemic narcotic analgesia. The use of procedural sedation is highly recommended, but any reduction technique may be attempted without medication when performed slowly and atraumatically. It is best to be comforTable with two or three techniques in case of a failed first attempt. Considerations in selection of a technique include ease of performance, effectiveness, requirement for sedation, number of assistants, and duration. The most common techniques are described below.
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Intra-articular injection of 10 to 20 mL of 1% lidocaine (10 mL provides a total dose of 100 milligrams of lidocaine) reduces the pain associated with reduction and can complement procedural sedation.30,31 After sterile skin preparation, introduce the needle at the hollow created by the displaced humeral head, just inferior to the acromion. US can facilitate intra-articular injection. Perform neurovascular examination before and after reduction.
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Complications associated with anterior glenohumeral dislocations include recurrence, rotator cuff tears, humeral head bony defects (Hill-Sachs deformity), glenoid labral defects (Bankart lesions), and rarely, neurovascular injuries.32 The most common complication is recurrent dislocation, and children and young adults may have a recurrence rate of more than 90%.32,33 Early surgical repair may decrease the recurrence rate, so patients with first-time shoulder dislocations should be referred for orthopedic evaluation.34,35,36
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The rotator cuff weakens with advancing age, and in older patients, anterior dislocation is usually associated with rotator cuff tears. Rotator cuff tears can be difficult to identify on ED examination after dislocation reduction, but can be suspected with weakness upon external rotation.32 Any patient with pain persisting for greater than 2 weeks should follow up with orthopedics. For further discussion, see chapter 280, "Shoulder Pain."
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Bony injuries are common and include fractures of the humeral head (Hill-sachs lesions) and glenoid (bony Bankart lesion) (Figures 271-8 and 271-9) and tears of the anterior glenoid labrum (soft Bankart lesion) and greater tuberosity. Such fractures are often evident only on postreduction films,23 and there is no specific ED treatment other than follow-up with orthopedics.
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Vascular injuries are rare, but when they occur, they tend to involve the axillary artery in elderly patients. Clinical findings of vascular injury include absent radial pulse, axillary hematoma, bruising of the lateral chest wall, and an axillary bruit.
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Nerve injuries, which occur in 10% to 25% of acute dislocations, are the result of traction neurapraxia. Most involve the axillary nerve, resulting in loss of sensation over the skin of the upper arm. This injury is temporary and resolves spontaneously. The motor portion of the axillary nerve supplies the teres minor and the deltoid, and injury can result in weakness of shoulder abduction and external rotation. Other nerves that may be injured are the radial, ulnar, median, musculocutaneous, and brachial plexus.32
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After reduction, place the arm in a shoulder immobilizer or sling that maintains the shoulder in adduction and internal rotation (Figure 271-10). Provide instructions for orthopedic follow-up in 1 week for uncomplicated dislocations and within 1 to 2 days for dislocations complicated by bony or soft tissue injury.37
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TRACTION-COUNTERTRACTION TECHNIQUE (MODIFIED HIPPOCRATIC)
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A modification of the Hippocratic method uses traction-countertraction (Figure 271-11). The patient is supine with the arm abducted and elbow flexed at 90 degrees. A sheet is tied and placed across the thorax of the patient and then around the waist of the assistant. Another sheet is tied and placed around the forearm of the patient at the elbow and the waist of the physician. Gradually apply traction to the proximal forearm as the assistant provides countertraction. Gentle internal and external rotation or outward pressure on the proximal humerus may aid reduction.
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Another version of the traction-countertraction technique is the Snowbird technique.28 The patient should sit upright in a chair or bed with the elbow flexed to 90 degrees. Place a belt or strap across the patient's proximal forearm, so the bottom of the belt can be used to apply downward pressure with the foot. Use an assistant to place a sheet across the patient's thorax to provide countertraction. Keep the patient's elbow at 90 degrees and apply traction to the extremity by stepping on the belt with the foot (Figure 271-12). Gentle external rotation will facilitate reduction.
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Place the patient prone with the dislocated extremity hanging over the side of the stretcher and a 10-lb weight attached to the wrist. Inject intra-articular lidocaine. Complete muscle relaxation is required. Reduction occurs in 20 to 30 minutes. Although the time to reduction can be a drawback, this technique is safe, effective, and easy to learn.
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SCAPULAR MANIPULATION TECHNIQUE
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The patient is positioned with weights in the same manner as the Stimson technique (Figure 271-13). After adequate sedation, the physician pushes the tip of the scapula medially using the thumbs, while stabilizing the superior aspect with the cephalad hand. This technique reports a 96% success rate.29
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EXTERNAL ROTATION TECHNIQUE (KOCHER'S TECHNIQUE)
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Place the patient supine with the affected arm adducted to the patient's side. With the elbow at 90 degrees of flexion, slowly externally rotate the arm (Figure 271-14). No longitudinal traction is applied. Perform the movement slowly to allow time for spasm and pain to resolve. Reduction is usually complete before reaching the coronal plane and is often not noted either by the patient or physician. If needed, the elbow may be brought anteriorly and internally rotated to the opposite shoulder.38
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The maneuvers for the Milch technique are external rotation, arm abduction to 180 degrees with simultaneous pressure on the humeral head, and in-line longitudinal traction with continued pressure on the humeral head (Figure 271-15).
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The Cunningham technique is based on the combination of humerus and scapular positioning and specific massage of a spasming biceps muscle (Figure 271-16). Seat the patient comfortably, as upright as possible, with shoulders relaxed. Supporting the affected arm, slowly and gently move the humerus into full adduction with the elbow in flexion. Have the hand of the affected extremity resting against the physician's shoulder. Gently massage the trapezius and deltoids, which helps to relax the patient. Then, gently massage the biceps at the mid-humeral level. Ask the patient to elevate and shrug or retract the shoulders (attempting to touch the scapulae together) and continue the biceps massage. The goal is to wait for the patient to relax fully and have the humeral head slip back into place.26
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