Shoulder dislocation and reduction

Shoulder dislocation and reduction

Author
Scott C Sherman, MD
Jeffrey Schaider, MD
Section Editor
Catherine B Custalow, MD, PhD
Mary Hochman, MD
Allan B Wolfson, MD
Deputy Editor
Jonathan Grayzel, MD, FAAEM



Last literature review version 16.2: May 2008 | This topic last updated: June 11, 2008 (More)


INTRODUCTION — Shoulder dislocations account for 50 percent of all major joint dislocations [1-5] . Anterior dislocation is most common, accounting for 95 to 97 percent of cases. Posterior dislocation accounts for 2 to 4 percent and inferior dislocation (ie, luxatio erecta, which means "to place upward") 0.5 percent [6] .

This topic review will discuss the mechanism of injury, evaluation, and reduction of shoulder dislocations. Evaluation of the patient with shoulder pain and other shoulder injuries are discussed elsewhere. (See "Evaluation of the patient with shoulder complaints" and see "Acromioclavicular injuries" and see "Frozen shoulder" and see "Glenohumeral osteoarthritis" and see "Multidirectional instability of the shoulder" and see "Presentation and diagnosis of rotator cuff tears" and see "Shoulder impingement syndrome").

ANATOMY — The shoulder is an inherently unstable joint (show figure 1A-1C). The glenoid is shallow, allowing for a wide range of motion, with only a small portion of the humeral head articulating with the glenoid in any position. The glenoid labrum is a fibrocartilaginous structure that surrounds the glenoid and inserts into the edge of the joint capsule. The distal portion of the joint capsule attaches to the humeral neck. The inferior glenohumeral ligament represents the anterior-inferior portion of the capsule. This ligament is thicker than the rest of the joint capsule and provides the strongest impediment to anterior dislocation.

The rotator cuff muscles provide additional support of the glenohumeral joint. The subscapularis muscle lies anterior to the joint capsule and acts as a secondary support resisting dislocation. Posteriorly the supraspinatus, infraspinatus, and teres minor pull the humeral head into the glenoid and help to prevent it from slipping anteriorly [7] .

The axillary nerve, the nerve most often injured with shoulder dislocations, runs inferiorly to the humeral head and wraps around the surgical neck of the humerus. It innervates the deltoid and teres minor muscles and the skin overlying the lateral shoulder ("shoulder badge" distribution). Shoulder anatomy is discussed in greater detail elsewhere. (See "Evaluation of the patient with shoulder complaints", section on Anatomy).

EVALUATION — Patients suspected of a shoulder dislocation need a thorough examination and frequently radiographic imaging to diagnose dislocation and associated injuries.

Anterior shoulder dislocation

Mechanism of injury - An anterior shoulder dislocation is usually caused by a blow to the abducted, externally rotated, and extended arm (eg, blocking a basketball shot). Less commonly, a blow to the posterior humerus or a fall on an outstretched arm may cause an anterior dislocation.

Examination - An anteriorly dislocated shoulder causes the arm to be slightly abducted and externally rotated. The patient resists all movement. The acromion appears prominent in thin individuals and there is loss of the normal rounded appearance of the shoulder (show picture 1). Clinicians perform a neurovascular examination paying particular attention to distal pulses and the function of the axillary nerve, which is most commonly injured in anterior shoulder dislocations. Axillary nerve dysfunction manifests as loss of sensation in a "shoulder badge" distribution, although this finding is not reliably present [8,9] . Deltoid muscle weakness may also be present, but is impractical to assess during the acute injury [10] . Some degree of axillary nerve dysfunction is present in 42 percent of patients with an anterior dislocation, but most patients recover completely without intervention [9,11] . In many cases, dysfunction resolves with reduction [12] .

Radiographic evaluation - Many clinicians obtain radiographs before and after reduction of an anterior shoulder dislocation. Initial x-rays confirm the diagnosis and exclude fractures; postreduction x-rays confirm successful reduction and exclude any fracture caused by the procedure [13] . In some cases there is no need for prereduction x-rays.

Clinically important fractures occur with approximately 25 percent of shoulder dislocations [12,14] . According to a retrospective case-control study, factors associated with fracture include age over 40, first-time dislocation, and traumatic mechanism (eg, fight or fall) [14] . When all three factors are absent, the negative predictive value for the presence of a fracture is 96.6 percent (95% CI 88.3-99.6). Based on this study and other observational data, we feel prereduction radiographs are unnecessary if none of the listed criteria are met and the clinician feels certain of the diagnosis of an anterior shoulder dislocation [15-17] .

Routine films include an anteroposterior (AP), a scapular "Y" view, and an axillary view. The diagnosis of an anterior shoulder dislocation may be straightforward and is often easily visualized on the AP view (show radiograph 1). The dislocated humeral head usually lies in a subcoracoid position (show figure 2). If the humeral head is subclavicular or subglenoid, there has been a greater degree of displacement and a concomitant greater tuberosity fracture or rotator cuff tear is usually present (show figure 2).

The scapular "Y" view is taken with the beam directed parallel to the scapular body. The "Y" is formed by the body, spine, and coracoid process. The glenoid falls in the center of the "Y" and is normally obscured by the humeral head. When an anterior dislocation is present, the humeral head appears medial to the "Y" (show radiograph 2). There may be false negatives with the scapular view, so an axillary view should also be obtained.

The axillary view is taken with the patient's arm abducted. The radiograph plate is placed on the patients shoulder and the x-ray beam projects through the axilla to the plate (show figure 3 and show radiograph 3). The patient's arm need not be abducted 90º, as this position causes pain. About 10 to 15º of abduction, or just enough to get the x-ray tube between the patient's arm and hip, is usually sufficient to obtain the appropriate view. Alternatively, a Velpeau axillary view can be obtained in which the patient leans back 15º over the edge of a table and the beam is directed from above the shoulder to the plate placed on the edge of the table.

Another view that may be helpful in determining the presence of a dislocation is the true AP (Grashey) view in which the beam is directed at a 45º angle in a medial to lateral direction with the x-ray plate just posterior and parallel to the scapular body. This view helps clinicians assess for subtle joint incongruities.

Associated fractures identified on plain radiographs include Hill-Sachs deformities, Bankart lesions, and greater tuberosity fractures. A Hill-Sachs deformity is a cortical depression in the humeral head made by the glenoid rim (show radiograph 4) [18] . They occur in 35 to 40 percent of anterior dislocations and are seen on the AP radiograph with the arm in internal rotation [7] . Bankart lesions occur when the glenoid labrum is disrupted and a bone fragment is avulsed (show radiograph 5). Bony Bankart lesions are present in 5 percent of patients, while soft tissue Bankart lesions (no bone is avulsed) occur in approximately 90 percent of patients less than 30 years old with an anterior shoulder dislocation [11,19] . Greater tuberosity fractures are present in 10 percent of patients (show radiograph 6) [20] .

Posterior shoulder dislocation

Mechanism of injury - A blow to the anterior portion of the shoulder, axial loading of an adducted and internally rotated arm, or violent muscle contractions following a seizure or electrocution represent the most common causes of posterior shoulder dislocation [21-23] .

Examination - Examination reveals prominence of the posterior shoulder with flattening anteriorly. The coracoid process appears prominent. The patient holds the arm in adduction and internal rotation and is unable to externally rotate (show picture 2) [24] .

Radiographic - Radiographic evidence of a posterior shoulder dislocation on a standard anteroposterior (AP) view is subtle and may go undetected in up to 50 percent of cases [25] . Clues to the diagnosis include the "light bulb" sign, rim sign, and trough line sign (show radiograph 3 and show radiograph 7).
The light bulb sign manifests because the humeral head is internally rotated and the tuberosities no longer project laterally, resulting in a circular appearance of the humeral head (show radiograph 7) [26] .

The rim sign refers to the distance from the medial aspect of the humeral head to the anterior glenoid rim. Although this distance may be normal with a posterior dislocation, if there is superimposition of these two structures or conversely a widened joint space (>6 mm), posterior dislocation should be suspected (show radiograph 3 and show radiograph 7).

The trough line sign is present when two parallel lines of cortical bone are seen on the medial cortex of the humeral head. One line represents the medial cortex of the humeral head, while the other line represents the "trough" of an impaction fracture (referred to as the "reverse Hill-Sachs lesion") on the anterior articular surface of the humeral head [27] .

Posterior shoulder dislocations are commonly associated with tuberosity and surgical neck fractures [24] . In cases where plain radiographs are indeterminate for dislocation, computed tomography is diagnostic and reveals the size of the articular surface impaction fracture, enabling the orthopedic surgeon to determine the most appropriate treatment [28] .

Inferior shoulder dislocation (luxatio erecta)

Mechanism of injury - Inferior dislocations are most commonly caused by axial loading with the arm fully abducted or forceful hyperabduction of the arm [29] . This dislocation frequently occurs when patients fall and suddenly grasp on to an object above their head resulting in hyperabduction.

Examination - Patients with this injury hold the involved arm above their head and are unable to adduct the arm [30] . The forearm is pronated and in most cases rests on the top of the head. Approximately 60 percent of patients will have some degree of neurologic dysfunction, with the axillary nerve most commonly involved [31] . In most cases, neurologic dysfunction resolves spontaneously following reduction. Rotator cuff tears or greater tuberosity fractures are present in 80 percent of cases. Arterial injury occurs in approximately 3 percent of patients, and can manifest as an absent or discrepant pulse [32] .

Radiographic examination - Radiographs reveal the humeral head beneath the coracoid or the glenoid (show radiograph 8). Associated fractures include the greater tuberosity (most common), acromion, scapula, humeral head, coracoid, and glenoid.

REDUCTION PROCEDURE

Informed consent — Inform the patient of the risks specific to the agents to be used, if procedural sedation is planned. The risks of the procedure itself are minimal and include the rare incidence of fractures of the humerus, glenoid, or coracoid process. Rotator cuff injuries may also occur, but are usually present prior to reduction. Axillary artery or nerve injury may occur during reduction, especially with techniques that require a significant amount of traction, but such complications are rare.

Materials — Depending on the reduction technique, no materials may be required. Approximately 10 to 15 pounds of weights are needed for the Stimson technique; bed sheets are used with the traction-countertraction technique. An assistant is required for many of the reduction techniques. If procedural sedation is deemed necessary, a nurse is required to prepare medications, administer oxygen, place the patient on appropriate monitors, and place an IV. Airway management equipment is moved to the bedside if procedural sedation is to be provided. One percent lidocaine, a 20 mL syringe, and a 20 gauge needle are needed when intraarticular lidocaine injection is given for analgesia.

Contraindications and precautions — There are no absolute contraindications to shoulder dislocation reduction. Delay may be necessary due to the need to treat life or limb-threatening conditions. Obtain orthopedic surgery consultation for elderly patients with dislocations that present subacutely (after 7 to 10 days) because of the relatively high incidence of vascular injury and fractures that occur with reduction attempts [7,8] .

Analgesia and sedation — Clinicians have several options for sedation when reducing anterior shoulder dislocations: no sedation, procedural sedation with intravenous medications, or intraarticular injection of lidocaine. Ultrasound guided interscalene block is a less commonly used but effective method [33] .

Reduction can frequently be obtained without analgesia in patients with anterior dislocations that are recent (ie, less than 24 hours), recurrent, or relatively atraumatic [10] . This approach is attractive because it is rapid, avoids complications from medications, and requires fewer personnel. Reduction without analgesia works best with techniques that do not require significant traction (ie, external rotation, scapular manipulation, or Milch technique) [34] .

Procedural sedation is administered to relieve pain and to reduce spasm in the muscles of the rotator cuff. Common medications include fentanyl and midazolam, ketamine, etomidate, and propofol [35,36] . Propofol and etomidate are particularly useful because of their rapid onset, short duration of action, and infrequent side effects. (See "Procedural sedation and analgesia in children").

Intraarticular lidocaine is inexpensive, provides pain relief, avoids potential complications from intravenous sedatives, and results in a rapid recovery time [37-39] . We suggest it be used in patients with comorbidities that put them at risk of complications from procedural sedation [40] . Injection is not made through skin or soft tissue that shows signs of infection. Coagulation disorders are a relative contraindication. Intraarticular injection fails more often in patients presenting more than 6 hours after injury [41] .

A lateral injection approach is best when the humoral head is dislocated anteriorly. To perform the injection, identify the acromion process over the lateral aspect of the shoulder. The injection is made laterally, approximately 1 cm inferior to the acromion process. After cleaning the skin and providing local skin anesthesia, inject 20 mL of 1 percent lidocaine using a 18 or 20 gauge needle into the glenohumeral joint. Direct the needle medially and inferiorly, and advance to a depth of 2.5-3.0 cm. Use of ultrasound guidance helps to ensure injection in the proper location [42,43] .

If procedural sedation is used, continuous monitoring with capnography and pulse oximetry is required, as well as frequent blood pressure measurements. Monitoring begins before any medications are given and continues until the patient is fully awake and able to protect their airway. (See "Procedural sedation and analgesia in children" and see "Carbon dioxide monitoring (capnography)").

Anterior shoulder dislocation reduction — No clear evidence exists supporting the superiority of any one of the many methods used to reduce anterior shoulder dislocations [44] . The method employed depends on clinician preference and the patient's condition. Generally, a technique that is quick, simple, and requires neither significant force nor intravenous medication is ideal. We suggest starting with scapular manipulation, and if unsuccessful, next attempting the external rotation technique (with or without the Milch technique). If reduction is not accomplished using these approaches, then traction-countertraction or the Stimson technique can be used. The techniques are described below.

Successful reduction is heralded by a "clunk" as the humeral head relocates and the return of the normal contour of the shoulder. With more gradual techniques (eg, external rotation), reduction may be more subtle with no appreciable "clunk." The ability of the patient to place the hand of the affected extremity on the opposite shoulder further confirms reduction.

Pediatric considerations — Traumatic glenohumeral dislocation in children less than 10 years is rare, accounting for less than two percent of all cases. Closed reduction is usually possible using the same techniques as adults. Nevertheless, because of the possibility of concomitant Salter-Harris (ie, growth plate) fractures, we recommend orthopedic consultation prior to any attempt at reduction, unless vascular compromise necessitates immediate treatment [45] .

Scapular manipulation — Scapular manipulation is quick, easy, and well tolerated by the patient and therefore is a good first maneuver. The method employs rotation of the scapula to disengage the humeral head from the glenoid and allow it to reduce into the glenoid. Success rates range from 80 to 100 percent [46-49] . The procedure takes 1 to 5 minutes and premedication is generally unnecessary. It is easiest to perform with the patient upright, but can also be performed with the patient prone if necessary.

Upright technique (preferred) - Place the head of the bed at 90 degrees. Have the patient dangle their legs over the side of the gurney and rest their unaffected shoulder against the upright portion of the bed. Encourage the patient to relax their shoulder muscles. Stand behind the patient and locate the scapula. Then simultaneously push the tip medially and the acromion inferiorly using the thumbs, thereby rotating the scapula. At the same time, an assistant provides gentle forward or downward traction on the arm [50,51] . Downward traction avoids movement of the patient's arm and may be advantageous. To exert downward traction, the assistant grabs the patient's wrist with one hand and the already flexed elbow with the other hand and pushes down on the elbow while holding the wrist in place (show picture 3).

Prone technique - The arm hangs off the side of the stretcher and is allowed to drop towards the ground. About 10 to 15 pounds of weight are hung from a prefabricated wrist splint as an alternative to an assistant providing traction [49] . The scapula is manipulated in similar fashion to the upright approach.

External rotation technique — The external rotation technique reduces anterior glenohumeral dislocation by overcoming spasm of the internal rotators of the humerus, unwinding the joint capsule, and enabling the external rotators of the rotator cuff to pull the humerus posteriorly [52,53] . This method is safe, easy to understand and teach, has no reported complications, and requires only one clinician [54,55] . It is successful in 80 to 90 percent of cases [54,56] . In one small case series, 81 percent of patients who were successfully treated required no sedation [54] .

Technique - To perform the technique, the patient lies supine and the elbow is flexed to 90º to relax the long head of the biceps and allow movement of the humeral head [20] . Grasp the elbow with one hand to maintain the adducted position of the arm and with the other hand hold the patient's wrist. Slowly, the patient is asked to let their arm fall to the side (externally rotate) as the clinician guides the hand (show picture 4). Whenever pain or spasm is felt, the movement is stopped and the muscles are allowed to relax. Gradually, over the course of 5 to 10 minutes, the arm externally rotates sufficiently that reduction can occur. Reduction generally happens with the arm externally rotated between 70 to 110 degrees [57] . Often the reduction is subtle and the "clunk" of the humerus rearticulating with the glenoid, typical of more forceful reduction techniques, is not appreciable.

Milch technique - If reduction is not achieved with the external rotation approach, even after the arm is fully externally rotated, the Milch technique can be added. To perform this technique abduct the now fully externally rotated arm into an overhead position, maintaining external rotation throughout the abduction. Reduction is achieved by applying gentle traction in line with the humerus and direct pressure over the humeral head with the clinician's thumb in the axilla (show picture 5).

Milch surmised that in the overhead position the muscles about the shoulder were in alignment with one another, and with cross-stresses thereby eliminated, nothing would prevent reduction of the humeral head [58,59] . Success rates of this technique range from 86 to 100 percent [34,60-62] .

Stimson technique — If the above techniques are unsuccessful, one alternative method is Stimson's technique, which involves placing the patient prone and hanging the affected extremity off the edge of the bed with 10 to 15 pounds of weight (show picture 6). Reduction is usually achieved within 30 minutes.

Traction countertraction — Traction-countertraction employs a sheet wrapped under the axilla. While one assistant provides gentle continuous traction at the wrist or elbow, the other provides countertraction with the sheet from the opposite side of the patient (show picture 7).

Spaso technique — The Spaso technique, employs gentle vertical traction and external rotation in the supine patient to reduce the dislocation, usually within 1 to 2 minutes (show picture 8) [63,64] .

Other approaches — Other methods include, the wrestling technique [65] , chair technique [66] , Eskimo technique [67] , Hippocratic technique [68] , and Kocher's method [69] . These techniques are either more complex or associated with undesirable complications.

The Hippocratic technique involves traction-countertraction with the clinician's foot placed in the patient's axilla. Kocher's method uses in-line traction of the patient's arm while it is abducted 45 degrees. While traction is maintained, the arm is externally rotated and the elbow is brought across the chest to the midline. Next, the arm is internally rotated until the patient's hand touches their shoulder. Both the Hippocratic and Kocher techniques are associated with a high rate of fractures, brachial plexus injury, and vascular injury compared to other techniques and should be avoided.

Posterior shoulder dislocation reduction — We suggest obtaining consultation with an orthopedic surgeon for all cases of posterior shoulder dislocation. Closed reduction is only attempted if the anterior articular surface defect ("reverse Hill-Sachs deformity") is less than 20 percent of the entire articular surface and the duration of dislocation is less than three weeks [21,24] . Closed reduction is frequently performed in the operating room under general anesthesia, but may be accomplished in the emergency department with procedural sedation.

Reduction involves axial traction on the adducted arm with the elbow flexed. Sheets are used in a similar manner to the traction-countertraction method to reduce an anterior dislocation (show picture 9) [3] . While traction is applied, the arm is externally rotated. Direct pressure directed anteriorly on the displaced humeral head or gentle lateral traction using a sheet looped under the axilla to unlock the glenoid rim may assist reduction. If successful, the arm is immobilized in a neutral position [24] .

Inferior shoulder dislocation reduction — Reduction of luxatio erecta (inferior shoulder dislocation) is achieved by traction-countertraction in line with the abducted humerus. Gentle, gradual adduction of the arm reduces the dislocation (show picture 10) [6,70,71] . Closed reduction is successful in most cases, unless a "buttonhole" deformity (humeral head is trapped in a tear of the inferior capsule) exists, in which case open surgical reduction is required [30] .

COMPLICATIONS — Reduction of an anterior shoulder dislocation in the emergency department is unsuccessful in 5 to 10 percent of cases [7] . Interposition of the biceps tendon, joint capsule, or fracture fragments within the joint is the most common cause [7,72] . Postreduction radiographs are necessary only if the clinician is uncertain whether the reduction has been successful. Postreduction radiographs are unlikely to identify a clinically significant fracture if none was identified on prereduction x-rays [16,17,73-75] .

Nerve and vascular injuries are rare complications of shoulder dislocation reduction. Nerve injury, most often of the axillary nerve, occurs more often in the elderly and possibly when methods that employ traction on the abducted arm are used [9] . Axillary nerve injury is managed conservatively. After four weeks, an EMG and nerve conduction study is performed. If surgery is necessary, it is best performed within three to six months [76] . Other less common nerve injuries include damage to the brachial plexus, radial, ulnar, and musculocutaneous nerves. Shoulder dislocation accounts for 7 percent of brachial plexus injuries [77] . Treatment is conservative (ie, physical therapy) and recovery generally occurs within three to four months [77,78] .

Axillary artery injury from attempts at shoulder reduction is rare, but more common in older patients with chronic dislocations [8] . Approximately 200 cases of axillary artery injury due to anterior shoulder dislocation have been reported [79] . Approximately 90 percent of these injuries occur in patients over the age of 50 due to joint capsule adhesions and atherosclerosis with loss of vessel elasticity [80] . If arterial injury is suspected based on increasing upper extremity pain, a diminished pulse, or a large hematoma, emergent reduction followed by axillary angiography is performed [80,81] . Venous injury rarely occurs, but usually presents as pain and swelling in the extremity from venous thrombosis [82] .

Rotator cuff tears after anterior shoulder dislocations are uncommon in younger patients, but occur in over half of patients over the age of 40 [8] . A complete rotator cuff tendon tear exists in 14 percent of patients with shoulder dislocation [82] . Diagnosing a rotator cuff tear is difficult immediately after an injury, but is often noted during follow-up by difficulty or pain when the patient abducts the arm. Such tears may be difficult to distinguish from axillary nerve injuries, which also present with abduction difficulty [82] .

Glenoid bone loss is a potential long-term complication of shoulder dislocation, not of reduction [83] .

FOLLOW-UP CARE — After successful reduction of an anterior shoulder dislocation, the shoulder is immobilized and the patient is referred to an orthopedic surgeon within one week. The most common complication of shoulder dislocation is recurrent dislocation, which occurs in 50 to 90 percent of patients under the age of 20 and in approximately 5 to 10 percent of patients over age 40 [7,8,84-86] . Efforts to prevent redislocation include altering the position of immobilization, increasing the duration of immobilization, physical therapy, and operative repair.

Immobilization — The traditional position of immobilization is adduction and internal rotation with a collar and cuff or sling and swathe or commercially available shoulder immobilizer. A cadaveric study, small observational trials, and several systematic reviews suggest recurrent dislocation may be less likely if the shoulder is immobilized in 10 degrees of EXTERNAL rotation. This theory is based on the commonly held belief that detachment of the glenoid labrum (ie, Bankart lesion) is the most common reason for high redislocation rates among younger patients. If the shoulder is immobilized in external rotation, the Bankart lesion lies closer to the glenoid labrum and may be more likely to heal [87-89] . A small nonrandomized observational trial of this method found the incidence of redislocation after 15 months was 6 of 20 patients (30 percent) immobilized in internal rotation and 0 of 20 (0 percent) immobilized in 10 degrees of external rotation [90] .

To immobilize the arm in external rotation, a wire-mesh splint covered with sponge is bent so that half of the splint is curved and fits over the patient's anterior trunk. The second half of the splint is straight and extends anteriorly and laterally such that when the arm is attached to the splint, it is externally rotated 10 degrees. The splint is fastened to the patient using a stockinette (show picture 11).

In patients under 30 years old, the shoulder is immobilized for three weeks [84,91-93] . In patients over 30 years old, the rate of redislocation is lower and early mobilization (after 1 week) is needed to limit joint stiffness [10,11,84,93] . Gentle pendular motion exercises are performed during the immobilization period to reduce the risk of frozen shoulder.

Operative treatment — Early indications for surgery include irreducible dislocations, displaced greater tuberosity fractures, and Bankart fractures that create glenohumeral instability [11] . Arthroscopic repair of a soft tissue Bankart lesion is sometimes recommended in young (less than 30), first time dislocators that engage in highly demanding physical activities because surgery reduces the high rate of subsequent redislocation in this group [10,19,94-98] . Generally, repair is performed within 10 days. Late surgical indications include recurrent instability or activity limitations [11] .

Rehabilitation — An intensive rehabilitation program may reduce the rate of redislocation, but this is not universally true [95,99,100] . During the initial period of immobilization (usually three weeks), the patient wears the immobilizer at all times unless bathing, mobilizing the elbow and wrist, or performing Codman's exercises (gentle shoulder range of motion exercises with the arm suspended). Abduction and external rotation must be avoided because these motions stress the anterior capsule [11] .

In subsequent weeks, active-assisted range of motion exercises and then isometric strengthening exercises for the muscles of internal rotation and adduction are added to the program. Generally by week 12, limited return to sporting activities is permitted, followed by full return to sporting activities as tolerated by week 16 [84,94,96] .

Patient education — Patients can be taught to reduce their own shoulder dislocation by clasping their hands together around the flexed ipsilateral knee from a seated position. The patient then leans back slowly and extends the hip, pausing whenever the pain is too much, until reduction occurs [57] .

SUMMARY AND RECOMMENDATIONS — Shoulder dislocations account for 50 percent of all major joint dislocations. Anterior dislocation is most common, accounting for 95 to 97 percent of cases. Shoulder anatomy and mechanisms of dislocation are discussed above. (See "Anatomy" above).

Anterior dislocation - An anteriorly dislocated shoulder causes the arm to be slightly abducted and externally rotated. The patient resists all movement and the acromion appears prominent (show picture 1). Proper evaluation includes a neurovascular examination, with particular attention to distal pulses and the function of the axillary nerve, which is most commonly injured. X-rays routinely obtained include the anteroposterior (AP), the scapular "Y" view, and the axillary view (show radiograph 1 and show radiograph 2). (See "Anterior shoulder dislocation" above).

Posterior dislocation - A posterior shoulder dislocation causes prominence of the posterior shoulder with flattening anteriorly. The coracoid process appears prominent. The patient holds the arm in adduction and internal rotation and is unable to externally rotate (show picture 2). Posterior shoulder dislocations are commonly associated with tuberosity and surgical neck fractures. Radiographic evidence of this dislocation on a standard anteroposterior view is subtle and often missed. Clues to the diagnosis include the "light bulb" sign, rim sign, and trough line sign (show radiograph 3 and show radiograph 7). (See "Posterior shoulder dislocation" above).

Inferior dislocation - Patients with inferior shoulder dislocation hold the involved arm above their head and are unable to adduct the arm. Approximately 60 percent of patients have some neurologic dysfunction, with the axillary nerve most commonly involved. Neurologic dysfunction usually resolves spontaneously following reduction. Rotator cuff tears or greater tuberosity fractures are present in 80 percent of cases. Arterial injury occurs in approximately 3 percent of patients. Radiographs reveal the humeral head beneath the coracoid or the glenoid (show radiograph 8). (See "Inferior shoulder dislocation (luxatio erecta)" above).

Clinically important fractures occur with approximately 25 percent of anterior shoulder dislocations. Factors associated with fracture include age over 40, first-time dislocation, and traumatic mechanism (eg, fight or fall). When all three factors are absent, the negative predictive value for the presence of a fracture is approximately 97 percent. (See "Anterior shoulder dislocation" above).

Reduction technique - No clear evidence exists supporting the superiority of any one of the many methods used to reduce anterior shoulder dislocations. Techniques that are quick, simple, and require neither significant force nor intravenous medication are ideal. We therefore suggest starting with scapular manipulation, and if unsuccessful next attempting the external rotation technique (with or without the Milch technique). If reduction is not accomplished using these approaches, then traction-countertraction or the Stimson technique can be used. The techniques are described in detail in the text, along with a discussion of analgesia, monitoring, and potential complications. (See "Reduction procedure" above).

Immobilization - Recurrent dislocation, the most common complication of shoulder dislocation, may be less likely if the shoulder is immobilized in 10 degrees of external rotation, as opposed to the traditional approach to immobilization using internal rotation. We suggest that following reduction of an anterior shoulder dislocation the patient's injured arm be immobilized in full adduction with slight external rotation (show picture 11). (See "Immobilization" above).