eMedicine - Shoulder Dislocations : Article by Scott Welsh, MD

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Shoulder Dislocations

Last Updated: July 7, 2004

Synonyms and related keywords: shoulder instability, anterior shoulder dislocation, posterior shoulder dislocation, inferior shoulder dislocation, subglenoid shoulder dislocation, subclavicular shoulder dislocation, intrathoracic shoulder dislocation, retroperitoneal shoulder dislocation, luxatio erecta, multidirectional shoulder instability, traumatic shoulder dislocation, atraumatic shoulder dislocation, atraumatic shoulder

AUTHOR INFORMATION Section 1 of 10

Author Information Introduction Indications Relevant Anatomy And Contraindications Workup Treatment Complications Outcome And Prognosis Future And Controversies Bibliography

Author: Scott Welsh, MD, Staff Physician, Department of Orthopedic Surgery, Borgess/Bronson Hospitals, Michigan State University
Coauthor(s): Mark Veenstra, MD, Consulting Staff, K Valley Orthopedics, Southwestern Michigan Sports Medicine Clinic

Scott Welsh, MD, is a member of the following medical societies: Michigan State Medical Society

Editor(s): Cato T Laurencin, MD, PhD, Lillian T Pratt Distinguished Professor and Chair, Department of Orthopedic Surgery, Professor of Biomedical Engineering, Professor of Chemical Engineering, The University of Virginia; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine; Pekka A Mooar, MD, Associate Professor, Department of Orthopedic Surgery, Temple University School of Medicine; Dinesh Patel, MD, FACS, Associate Clinical Professor of Orthopedic Surgery, Harvard Medical School; Chief of Arthroscopic Surgery, Department of Orthopedic Surgery, Massachusetts General Hospital; and Mary Ann E Keenan, MD, Professor of Orthopedic Surgery, University of Pennsylvania School of Medicine; Chief, Neuro-Orthopedic Service, Department of Orthopedic Surgery, Hospital of the University of Pennsylvania

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INTRODUCTION

Section 2 of 10

Author Information Introduction Indications Relevant Anatomy And Contraindications Workup Treatment Complications Outcome And Prognosis Future And Controversies Bibliography

Shoulder dislocations account for almost 50% of all joint dislocations. Most commonly, these dislocations are anterior (90-98%) and occur due to trauma. Most anterior dislocations are subcoracoid in location. Subglenoid; subclavicular; and, very rarely, intrathoracic or retroperitoneal dislocations may occur.

For excellent patient education resources, visit eMedicine's Breaks, Fractures, and Dislocations Center. Also, see eMedicine's patient education article, Shoulder Dislocation.

Problem: See Complications for a discussion of associated injuries.

Frequency: Shoulder dislocations account for almost 50% of all joint dislocations.

Etiology: The usual mechanism of injury is extreme abduction, external rotation, extension, and a posterior directed force against the humerus. Forceful abduction or external rotation alone can also lead to dislocation (about 30% of cases), as can a direct blow to the posterior humerus (29%), forced elevation and external rotation (24%), and a fall onto an outstretched hand (17%).

Posterior dislocations are less common (2-10%) and are the result of an axial load applied to the adducted and internally rotated arm. Classic posterior dislocations also occur as a result of electrocution or seizures because of the strength imbalance between the internal rotators (subscapularis, latissimus dorsi, pectoralis major muscles), which overpower the external rotators (teres minor and infraspinatus muscles).

Inferior dislocations are rare and result from a hyperabduction force that causes the humeral neck to lever against the acromion. Diagnosing inferior dislocations is critical because of the high incidence of complications. Neurologic injuries (particularly axillary nerve lesions) are associated with inferior dislocations in as many as 60% of cases, vascular injuries occur in about 3.3% of cases, rotator cuff tears in occur in 80-100% of cases, and greater-tuberosity fractures and pectoralis major avulsions are also associated with inferior dislocations.

Superior dislocations are extremely rare and result from an extreme force in a cephalic direction to the adducted arm. Acromioclavicular injuries and fractures of the acromion, clavicle, and tuberosities may occur with superior dislocations.

Atraumatic instability is usually multidirectional and commonly occurs in individuals with generalized hyperlaxity due to connective tissue disorders such as Ehlers-Danlos syndrome and Marfan syndrome. A small or flat glenoid fossa, excessive anteversion or retroversion of the glenoid, weak rotator cuff muscles, neuromuscular disorders, or a redundant capsule may also jeopardize the concavity-compression, adhesion-cohesion, or the glenoid suction-cup phenomena that aid in stability of the shoulder.

Multidirectional instability most commonly occurs in younger populations, usually in patients younger than 30 years, and is often familial and bilateral. The first dislocation often occurs after a minor injury or after a period of disuse. Patients may experience subluxations that progress over time to actual dislocations, which spontaneously reduce. These dislocations may be voluntary or involuntary. Voluntary dislocations have been associated with psychiatric illnesses and may be used in attention seeking behavior. Surgery should be avoided in this population because the instability is likely to recur.

Clinical: Patients with anterior dislocations usually present with the arm in slight abduction and externally rotated. The humeral head can often be palpated in the front of the shoulder. Internal rotation and adduction are limited. Movement is usually very painful due to muscle spasms.

Patients with posterior dislocations present with the arm internally rotated and adducted. External rotation is severely limited. A posterior prominence is usually palpable, the anterior shoulder is flattened, and the coracoid process is more prominent. Historically, these dislocations have been missed or misdiagnosed as a frozen shoulder.

Inferior dislocations lead to a condition known as luxatio erecta, which describes a classic presentation of the arm abducted 110-160° with the forearm resting on or behind the patient's head.

INDICATIONS Section 3 of 10

Author Information Introduction Indications Relevant Anatomy And Contraindications Workup Treatment Complications Outcome And Prognosis Future And Controversies Bibliography

Surgery may be indicated if patients are unable or unwilling to change their occupation or avoid participating in high-risk sports and if they have recurrent dislocations or subluxations.

RELEVANT ANATOMY AND CONTRAINDICATIONS Section 4 of 10

Author Information Introduction Indications Relevant Anatomy And Contraindications Workup Treatment Complications Outcome And Prognosis Future And Controversies Bibliography

Relevant Anatomy: See Surgical therapy.

Contraindications: Surgery should be avoided in patients with voluntary dislocations associated with psychiatric illnesses because the instability is likely to recur.

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Introduction
Indications
Relevant Anatomy And Contraindications
Workup
Treatment
Complications
Outcome And Prognosis
Future And Controversies
Bibliography

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WORKUP

Section 5 of 10

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Imaging Studies:

Radiography: Conventional radiography should be performed in all patients with suspected dislocations to confirm the diagnosis and also to exclude associated fractures prior to any attempted reduction. Routine radiographs should include at least an anteroposterior (AP) view and an axillary view.

The AP view can be obtained in neutral, internal, or external rotation. In internal rotation, one can easily see a Hill-Sachs lesion of the posterolateral humeral head.

The axillary view nicely shows glenohumeral subluxation or dislocation as well as anterior or posterior glenoid rim fractures. A standard axillary view may be difficult in the acute injury setting because it requires 90° of abduction; however, many modifications exist to avoid excessive movement of the painful extremity. For example, the transverse axillary lateral requires the patient to abduct the arm only 10-30°.

Other views that may be useful include the scapular Y view, which is helpful for diagnosing dislocations and scapular fractures. This view, however, should not replace the axillary view because it does not show subtle subluxations of the glenohumeral joint or fractures of the glenoid rim.
- The true AP or Grashey view is helpful in assessing subtle joint incongruity, superior or inferior subluxation, degenerative changes, or glenoid hypoplasia.
- The Garth or West Point view is useful in detecting bony Bankart fractures of the anteroinferior glenoid rim as well as Hill-Sachs defects. This view is advantageous in the acute setting because it does not necessitate the patient moving the arm.
- The Stryker notch view can also be useful in detecting Hill-Sachs lesions. However, this view is of limited usefulness in detecting subluxations or glenoid fractures.

Computed tomography (CT) arthrography, magnetic resonance imaging (MRI), and/or magnetic resonance arthrography may be helpful in assessing some shoulder dislocations.

CT arthrography was commonly used in the past to evaluate patients with glenohumeral instability either after the initial dislocation or with recurrent instability. However, today, it is used only when an MRI is contraindicated or if glenoid version abnormalities are suspected.

MRI and magnetic resonance arthrography have been shown to be more sensitive than other methods in detecting labral and ligamentous pathology, rotator cuff and cartilage tears, capsular abnormalities, and biceps injuries. MR arthrography is more sensitive than MRI alone and is the study of choice after a shoulder dislocation, particularly in cases of recurrent instability, and it is superior to MRI for diagnosing the pathologic lesions mentioned above.

TREATMENT

Section 6 of 10

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Medical therapy:

Closed reduction

Many methods can be used to successfully reduce a dislocation, but the most important factor for a successful reduction is time to reduction. As time passes, the muscles become more spastic, and the reduction becomes significantly more difficult. Methods of reduction include the following:

The Hippocratic method involves longitudinal traction on the arm and a counterforce to the axilla, usually with the heel of the foot.
The Kocher method involves traction to the elbow with external rotation of the humerus and adducting the elbow toward the chest. This method is not currently recommended because of its association with neurovascular complications and proximal humerus fractures.
The external rotation method, which is a modification of the Kocher maneuver, involves flexing the elbow to 90° and slowly adducting the arm to the patient's side. The arm is then carefully externally rotated stopping every few degrees to wait for the muscle spasms to subside.
The Stimson technique requires the patient to be positioned prone. The patient's arm is allowed to hang over the edge of the bed with about 10 pounds of weight hanging from the wrist.
The Milch technique is very successful and relatively atraumatic. It involves the surgeon abducting the patient's arm with one hand while applying pressure to the humeral head with the other hand. When the patient's arm is fully abducted, external rotation and traction are applied. The success rate of this technique is 72-89%. Only about one third of patients require sedation or analgesia. Lacey and associates modified this technique by performing the Milch maneuver with the patient in the prone position.
Scapular manipulation is also relatively atraumatic and incorporates internal rotation of the scapula to disengage the humeral head. The patient is placed prone and 5-15 pounds of traction are applied to the forearm. The inferior angle of the scapula is then rotated medially, and the superior aspect is rotated laterally. The success rate is 92-96%.
The Spaso technique was recently introduced. This technique involves the use of vertical traction while the surgeon grasps the wrist or forearm with the patient supine. Traction is maintained as the shoulder is externally rotated. The opposite hand may be used to push posteriorly on the head. Continual traction for several minutes will often overcome the spastic rotator cuff muscles, which are more relaxed with the arm in a forward-flexed position (roughly 90°). The success rate is 87.5%.
Traction/countertraction is the method preferred by many authors. This method involves the application of longitudinal traction in the direction of the deformity and countertraction by using a sheet wrapped around the patient's chest. The shoulder is gently rotated internally and externally to disengage the head from the glenoid.

Sedation and analgesia

Many options are available to achieve the patient's maximum comfort and to increase the ease of the reduction. If a dislocation is identified early, reduction may be achieved without the use of narcotics, sedatives, or muscle relaxants, particularly when the scapular manipulation technique is used.

More commonly, however, some type of analgesic is combined with a sedative or muscle relaxant. Morphine or fentanyl is generally administered on the patient's arrival in the emergency department. A sedative such as Versed or etomidate is subsequently used to achieve reduction. Recently, etomidate has become a popular choice because of its rapid onset (<30 s) and short duration of effects (<5 min). It also provides excellent muscle relaxation and is more predictable than Versed. Typically, a narcotic analgesic is administered prior to administering etomidate, as etomidate does not contain any analgesic properties.

Another alternative is the intra-articular administration of lidocaine. Usually, about 20 mL of 1% lidocaine without epinephrine is injected with a 1.5-inch 20-gauge needle about 2 cm lateral and inferior (or posterolateral) to the acromion. The needle is directed toward the glenoid in a slightly caudal direction. This method has been compared to intravenous sedation and found to be as effective for pain control and ease of reduction. Intraarticular lidocaine has been shown to be as successful or slightly less effective in achieving reduction, primarily in cases of delayed (ie, >5.5 h) presentation.

Conservative treatment

Conservative treatment of shoulder dislocations remains a controversial topic in orthopedics. Traditionally, patients have been placed in a sling with or without an immobilizer strap for a period of 1-6 weeks. Internal rotation and adduction is the classic position of immobilization, and external rotation and abduction are avoided.

Two recent studies, however, shed new light on this topic. An MRI study showed the best coaptation of the anteroinferior glenoid labrum to the glenoid rim, with the arm in about 35° of external rotation and held at the patient's side (Itoi, 2001). Another study in cadavers revealed that a range from full internal rotation to about 30° of external rotation exists in which the labrum is coapted to the glenoid when the arm is in slight adduction (Itoi, 1999). Flexion or abduction tends to displace the labrum. Despite these findings, the position of mobilization remains in slight internal rotation to prevent recurrent dislocations.

The duration of immobilization is also a source of debate. Most authors recommend 3-4 weeks of immobilization in patients younger than 30 years and 7-10 days of immobilization in patients older than 30-40 years. However, a recent study revealed a significant reduction in the recurrence rate from 78% to 44% at 1 year and from 85% to 69% at 2 years if the arm was immobilized for 4-7 weeks instead of 0-3 weeks. The recurrence-free period was also extended from 4 to 14 months with longer treatment. On the contrary, Hovelius et al performed a prospective randomized trial with 10-year follow-up and found that the duration of immobilization had no effect on the long-term recurrence rate.

Rehabilitation usually begins after 3 weeks of immobilization, starting with active assisted range of motion (ROM) with external rotation limited to 20°, pendulum exercises, and scapular retractions beginning 4-6 weeks after injury. Beginning 7-8 weeks after injury, active ROM are prescribed, with external rotation limited to 45°, isometric cuff strengthening, and scapular exercises and retraining. Active ROM with terminal stretch, isotonics, and scapular strengthening are performed 9-12 weeks after injury. Patients may return to noncontact sports with no overhead requirements after 3 months. Athletes may return to contact and overhead sports after 4 months. The success of this regimen largely depends on the patient's age at the time of the initial dislocation.

Greater tuberosity fractures associated with dislocation and advanced age are good prognostic indicators for successful nonoperative treatment. Activity modification, such as avoiding overhead work, heavy manual labor, and high-risk sports can minimize the risk of future dislocations.

Recurrence rates for nonoperative treatment

Nonathletes have a 30% recurrence risk with nonoperative treatment, and athletes have an 82% recurrence risk with nonoperative treatment.

If the dislocation was the patient's first, recurrence rates with nonoperative treatment depend on age, as follows:

Patients aged 1-10 years have a 100% recurrence rate.
Patients aged 11-20 years have a 27-95% recurrence rate.
Patients aged 21-30 years have a 40-79% recurrence rate.
Patients aged 31-40 years have a 40-72% recurrence rate.
Patients aged 41-50 years have a 0-24% recurrence rate.

Surgical therapy: Surgery may be indicated if patients are unable or unwilling to change their occupation or avoid participating high-risk sports and they have recurrent dislocations or subluxations.

The question of timing of surgery remains unclear. Several studies have recently advocated arthroscopic or open stabilization procedures after the initial dislocation in lieu of the traditional method of surgical intervention after a trial of nonoperative treatment in patients with a history of multiple dislocations or subluxations. In military recruits and in young athletes aged 17-27 years, recent studies have shown far superior results with surgery after the initial dislocation in these patients, as opposed to the results after a trial of nonoperative treatment.

In a recent prospective trial, the repeat dislocation rate was 4% after arthroscopic stabilization of acute dislocations and 94.5% after nonoperative treatment (Larrain, 2001). In another recent study, patients were randomly assigned to immobilization and early surgical intervention. In these patients, the repeat dislocation rate was 15.9% at 2 years, and the recurrence rate was 47% in patients treated nonoperatively.

Historically, open stabilization procedures have had a rate of repeat dislocation rate slightly lower than that of arthroscopic procedures, but the discrepancy is significantly less today, as technical skills and anchoring devices have improved. In a recent study in Sweden, the arthroscopic failure rate was 15%, compared with an open stabilization rate of 10%. External rotation was better maintained in the arthroscopic group, in whom it was 90°, compared with the group that underwent open procedures, in whom it was 80°.

Another study of arthroscopic and open reconstruction revealed failure rates of 33% and 8%, respectively. However, many authors believe that their arthroscopic results are the same, if not better, than their results with open procedures for both athletes in contact sports and athletes in noncontact sports. The current trend is toward minimally invasive surgery, and the results of arthroscopic instability repairs will continue to improve. A key element in a successful instability procedure is addressing any capsular laxity, whether by means of an open capsular shift, an arthroscopic capsular plication, thermal capsulorrhaphy, or rotator interval closure.

COMPLICATIONS Section 7 of 10

Author Information Introduction Indications Relevant Anatomy And Contraindications Workup Treatment Complications Outcome And Prognosis Future And Controversies Bibliography

Shoulder dislocations result in various associated arthroscopic findings and various vascular and neurologic complications. One must be astute when examining patients for neurovascular compromise, both prior to and after reduction attempts. Most patients with a first-time dislocation also have a Bankart lesion (ie, an avulsion of the anterior capsulolabral complex from the glenoid rim with disruption of the medial scapular periosteum).

Variations of this injury include a bony Bankart lesion, in which the labrum remains intact but a fracture occurs through the anterior glenoid rim. A Perthes lesion is similar to a Bankart lesion, except the medial scapular periosteum remains intact; thus, the labrum may appear normal on MRI and arthroscopy unless the arm is abducted and externally rotated away from the neutral position.

An anterior labroligamentous periosteal sleeve avulsion (ALPSA) lesion differs from the Bankart lesion in that the anterior labrum is medially displaced. It heals in an abnormal position, leading to an incompetent anterior inferior glenohumeral ligament. Hill-Sachs lesions commonly occur and are compression fractures that result from impaction of the posterolateral humeral head against the anterior/inferior glenoid rim, which can occasionally result in a loose body.

Rotator cuff tears are rare in young individuals but common in older patients. Approximately 30% of patients older than 40 years have a cuff tear, as do about 80% of patients older than 60 years. Greater tuberosity fractures also occur with dislocations in older patients, and these have been associated with a lower incidence of recurrent dislocations. Older patients are less likely to have a Bankart lesion and more likely to have a cuff tear, a greater tuberosity fracture, or an avulsion of the capsule and subscapularis from the lesser tuberosity. Younger patients more commonly have labral tears. Coracoid fractures may also occur as a result of an anterior dislocation or a difficult reduction attempt.

Vascular injuries are rare, but they may occur with anterior or inferior dislocations, especially in older patients with atherosclerosis of the axillary artery. The humeral head displaces the artery anteriorly over the head, and the pectoralis muscle acts as a fulcrum against the artery, leading to rupture. Arteriography should be performed if a vascular injury is possible. Because of the proximity of the 2 structures, arteriography should be strongly considered any time a brachial plexus injury is observed. Most commonly, patients present with delayed vascular compromise secondary to an intimal injury and resultant occlusion. Acute obstruction or rupture occurs in about 3.3% of cases of luxatio erecta. Pseudoaneurysm may also occur, especially after recurrent dislocations. Subclavian vein thrombosis may result from a venous injury and present with unilateral swelling and pain.

Neurologic injuries are more common than vascular injuries, particularly axillary neuropraxias, which are found in about 8-10% of patients with anterior dislocations. Patients have weakness in abduction and external rotation, as well as numbness over the lateral aspect of the upper arm. Among possible neurologic complications, these lesions have the poorest prognosis. Radial nerve injuries must also be considered in cases of axillary nerve damage because both arise from the posterior cord. These injuries may result in weak thumb, wrist, and elbow extension, as well as numbness on the dorsal aspect of the hand.

Long thoracic nerve palsies may also result from traction on the nerve, leading to scapular winging due to paralysis of the serratus anterior. Suprascapular nerve palsies cause weakness in abduction and external rotation. Dorsal scapular nerve injuries cause weakness in abduction. Musculocutaneous injuries lead to weak elbow flexion and supination, as well as lateral forearm numbness.

Arthroscopic findings after shoulder dislocation include the following:

Bankart lesions in 80-89% of patients
Anterior capsular insufficiency in 74% of patients
Hill-Sachs lesions in 67% of patients
Inferior glenoid labral tears in 51% of patients
Glenohumeral ligament insufficiency in 50% of patients
Partial or complete rotator cuff tears in 13% of patients
Dysplastic glenoid in 13% of patients
Biceps tendon lesions in 12% of patients
Brachial plexus injuries in 11% of patients
Posterior glenoid labral tear in 11% of patients
Axillary nerve injuries in 8-10% of patients
SLAP lesions in 8% of patients
Partial subscapularis tear in 8% of patients
Loose bodies in 5% of patients

OUTCOME AND PROGNOSIS Section 8 of 10

Author Information Introduction Indications Relevant Anatomy And Contraindications Workup Treatment Complications Outcome And Prognosis Future And Controversies Bibliography

See Medical therapy and Surgical therapy.

FUTURE AND CONTROVERSIES Section 9 of 10

Author Information Introduction Indications Relevant Anatomy And Contraindications Workup Treatment Complications Outcome And Prognosis Future And Controversies Bibliography

See Conservative treatment.

BIBLIOGRAPHY Section 10 of 10

Author Information Introduction Indications Relevant Anatomy And Contraindications Workup Treatment Complications Outcome And Prognosis Future And Controversies Bibliography

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Shoulder Dislocations excerpt