Adam M. Smith
Traumatic Dislocation
Acute, traumatic dislocation of the shoulder is a common injury. Anterior dislocation is usually associated with a shoulder that is positioned in abduction and external rotation with an anteriorly directed force on the humeral head.
At the patient's initial presentation, care should be taken to complete a comprehensive examination of the entire upper extremity for any evidence of neurovascular injury, with special care to examine the axillary and musculocutaneous nerve distributions. Shoulder dislocation has been shown to result in clinically apparent neurologic injury in about 10% of patients.1 Although most of these injuries are clinically insignificant and recovery is complete, appropriate documentation is important. Accurate examination of neurologic function is vital prior to any reduction maneuver. Although neurologic studies are not routinely recommended, patients who present with initial muscular paralysis may be examined with electromyogram (EMG) and nerve conduction studies at least 3 weeks after the injury if clinical recovery does not occur.
Imaging
Initial imaging studies of the glenohumeral joint should include a minimum of three views and must include an adequate axillary view. Patients and staff may be reluctant to perform an axillary radiograph owing to concerns about pain with arm positioning. However, an adequate axillary radiograph can be safely obtained using a Velpeau view (Fig. 34-1).
Hill-Sachs lesions (impaction injury of the humeral head to the glenoid) and fractures of the humeral neck, glenoid, or tuberosities are not uncommon and should be noted prior to reduction to avoid confusion with an iatrogenic injury. Large humeral head impactions (engaging Hill-Sachs lesions) and glenoid bone loss have been identified as poor prognostic predictors of outcome in patients who undergo arthroscopic instability repair.2
Pathoanatomy
With an acute anterior-inferior dislocation of the glenohumeral joint, an injury to the anterior soft tissues of the shoulder occurs with detachment of the labrum and the inferior glenohumeral ligament complex from the anteroinferior aspect of the glenoid Bankart lesion.3Although multiple intra-articular injuries have been documented with arthroscopy after shoulder dislocation, Bankart lesions have been described as the “essential” lesion of shoulder instability and are seen in more than 90% of acute, traumatic shoulder dislocations.4However, labral tearing alone is often not enough to lead to recurrent shoulder instability and is usually associated with capsular stretching. Initial management, both operative and nonoperative, is directed at the management of these labral and capsular injuries.
Reduction
A cooperative, relaxed patient is imperative when attempting reduction of the glenohumeral joint. Although some physicians are able to successfully reduce shoulders without sedation on the playing field or immediately after a dislocation event, muscle spasm and pain occur, with most patients requiring medication to assist with the reduction maneuver. Injection of the glenohumeral joint with intra-articular lidocaine has been found to be a safe and effective method of analgesia to assist with reduction maneuvers.5
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With this method, 10 to 15 mL of 1% lidocaine is injected into the glenohumeral joint.
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Figure 34-1 Positioning for the Velpeau axillary view is easy to perform. |
Multiple reduction maneuvers have been discussed in the literature for anterior-inferior dislocations. Postreduction radiographs with at least three views including an axillary are recommended to evaluate the glenohumeral joint for a complete concentric reduction and the presence of any fracture.
One of the most common methods used is the traction-countertraction technique.6 In this method the patient lies in the supine position with a sheet around the upper thorax. An assistant provides a steady countertraction force to the thorax while the surgeon applies steady gentle traction to the arm in the direction of the dislocation.
The Stimson technique is an excellent technique (Fig. 34-2). The patient is placed prone and the arm allowed to hang off the side of the table perpendicular to the body. A light weight (approximately 5 pounds) is attached to the wrist, and the patient is allowed to relax. Reduction is usually achieved within 10 to 20 minutes as the gentle prolonged traction allows muscle relaxation and reduction of the glenohumeral joint.
The external rotation method can be performed by one person.7 The reduction is performed with the patient in the supine position, and the affected elbow flexed to 90 degrees with the arm adducted to the level of the chest and the shoulder flexed forward 20 degrees. With the elbow stabilized, the surgeon gently externally rotates the shoulder with minimal force until the shoulder is reduced. Elderly patients or those with subclavicular dislocations should not undergo this technique because of the risk of iatrogenic fracture.
Immobilization
After the initial dislocation has been reduced and the glenohumeral joint is concentric on radiographic examination, a period of immobilization is warranted to maintain reduction, promote healing of the injured soft tissues, and decrease the chance for recurrent dislocations. Recommendations for length of immobilization of acute dislocations are usually 4 to 6 weeks.
Although the most desirable position for immobilization is debated, most authors recommend use of a simple sling with the shoulder in the internally rotated position. Immobilization of the shoulder in external rotation has recently been suggested. With this method, a brace is used to immobilize the shoulder in the externally rotated position. This position has been shown on MRI to reduce anterior joint cavity volume and allow a more anatomic reduction of the Bankart lesion to the glenoid neck and rim owing to increased tension on the anterior soft tissues and subscapularis muscle. This position is not tolerated well by most patients. Further studies examining the role of external rotation bracing in the immediate postinjury period will be required.8,9
Therapy
Early therapy with trained personnel is warranted to regain shoulder motion and strength. Motion exercises including active-assisted motion such as pulley and wand therapy are started after the immobilization period. Rotator cuff, periscapular, and body core strengthening and neurore-education are instituted after pain and motion have improved.
Athletes with an injury that occurs in season offer special challenges. In uncomplicated initial cases, return to play or activities is allowed only when range of motion and strength are equal to the uninjured shoulder.10 Special braces designed to limit overhead motion (abduction and external rotation) have been used with varying degrees of success to prevent instability so that athletes can return to play after in-season dislocation. If the athlete has recurrent instability in season, athletes and their parents should have a thorough understanding of the risks of continued participation with a grossly unstable shoulder.
Results
The results of conservative care of acute shoulder dislocation are mixed and seem to depend on the age of the patient and desire to continue participation in the inciting event. Patients 18 years old or younger and contact athletes
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have higher rates of recurrent dislocation and have been reported to have recurrent instability in >90% of patients with standard nonoperative regimens (immobilization in internal rotation in a sling, therapy, and return to activities). This high recurrence rate has led some authors to pursue other forms of nonoperative therapy such as initial immobilization in external rotation to minimize the rate of recurrence. Early results from multicenter trials are not yet available.8,9 Other authors have explored early operative intervention when managing younger patients with arthroscopic Bankart repair with short-term results that have been favorable.11 Long-term sequelae of recurrent shoulder instability include glenohumeral arthritis and have been identified in approximately 20% of patients with long-term follow-up.12
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Figure 34-2 Stimson technique for glenohumeral reduction. |
Older patients with less demanding activities usually can be managed with conservative treatment and rehabilitation. Although prolonged weakness of the shoulder may be owing to neurologic injury, rotator cuff tearing is known to occur in patients older than 35 years of age. Patients with continued weakness of the rotator cuff after a few weeks of rehabilitation should be examined closely for cuff tearing and may require appropriate imaging. Patients with tears of the subscapularis are particularly prone to developing recurrent instability and should be aggressively managed with operative treatment.13,14 Patients with subscapularis tearing may demonstrate increased passive external rotation of the shoulder and inability to perform lift-off, belly-press, or bear-hug tests.15
Surgical treatment is generally warranted for patients who fail nonoperative intervention and continue to dislocate despite aggressive rehabilitation. Patients with irreducible dislocations or open injuries warrant urgent surgical intervention. The treatment of young patients (<18 years of age) or contact athletes with acute dislocations is controversial, and recommendations continue to emerge. Although characterization of what constitutes a chronic dislocation is not well-defined in the literature, patients with a shoulder dislocation present for ≥3 weeks are managed much differently than those with acute dislocations and frequently require operative intervention. These patients are generally cognitively impaired or multitrauma patients and should undergo attempts at closed reduction only in a well-controlled setting with adequate sedation and muscle relaxation to avoid iatrogenic fracture or neurovascular injury.
Multidirectional Instability
Multidirectional instability (MDI) is difficult to define. Diagnosis of MDI is usually subjective, and agreement on classification has not been achieved.16 However, it is generally accepted that patients with MDI have instability in more than one direction (anterior, inferior, or posterior). The treatment of MDI was first defined by Neer and Foster.17 Our understanding continues to evolve and is the subject of several ongoing studies.
Pathoanatomy/Diagnosis
Anatomic changes in patients with MDI include a large, patulous inferior capsule that increases glenohumeral joint volume, thus diminishing the checkrein effect of the glenohumeral ligaments. Rotator interval tissue is usually thinned and less robust than normal. Although the tissue in patients is often less than ideal, neurologic abnormalities also exist and seem to play a key role in the MDI syndrome,18 A large joint capsule combined with loss of proprioceptive
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control of the rotator cuff likely leads to loss of concavity compression. Periscapular muscle control for scapular positioning may lead to inappropriate glenoid position, thus leading to instability. This is supported by recently reported data that atypical patterns of muscle activity with resulting dysfunctional neuromuscular control of the rotator cuff and periscapular musculature is a major contributing factor to the pathologic cause of MDI.19,20
Although some patients complain of gross instability or frequent complete dislocation of the shoulder, most patients with MDI complain of vague sensations of pain or instability with routine activities of daily living or at the end points of motion. MDI is seen in two broad categories of patients: patients with general ligamentous laxity at baseline, and patients who have long-standing microtrauma with no discreet injury (swimmers, gymnasts, throwers, weight lifters, and patients involved in racquet sports).
Patients with generalized ligamentous laxity are able to demonstrate hyperextendable joints (elbows, knees, wrists, metacarpophalangeal). These patients generally have no tear of the labrum (Bankart lesion), but may have an excessively “loose” shoulder with an enlarged inferior capsular pouch. Patients with recurrent microtrauma also frequently have loose shoulders from acquired activities, such as swimming, that require extreme ranges of motion for maximum performance and result in stretching of the shoulder capsule through repetitive stress. However, in these patients, an acute event occurs causing injury to the already capacious capsule. These patients may have a labral or capsular tear and should be differentiated from patients with generalized ligamentous laxity.
Patients with MDI often present with subtle physical findings. Loose shoulders are common findings in young patients (particularly girls), and reproduction of new or pathologic instability leading to the patient's symptoms should be the focus of the examination. Examination of the asymptomatic shoulder is important and can give insight to abnormalities in the affected shoulder. Identification of a sulcus sign with prominent humeral head depression below the acromion with gentle inferior traction applied to the wrist indicates lax capsular rotator interval tissue. Asymmetric shoulder laxity can be identified by examining for the amount of humeral head translation off of the glenoid rim. Examination under anesthesia is extremely useful and allows the surgeon to examine the shoulder with variable amounts of rotation to identify areas of asymmetrical laxity.21,22
Rehabilitation
Patient education is an important first step in rehabilitation. An adequate understanding of the underlying problem seems to facilitate patient compliance. Functional activities should not only include strengthening of the rotator cuff and periscapular muscles, but also should emphasize retraining of the scapula and dynamic stabilizers of the shoulder for appropriate positioning of the glenoid. Patients should be discouraged from any voluntary subluxation. Rehabilitation may take several months, and patients (and physicians) may become frustrated. However, a minimum of 6 months of therapy (some authors recommend a year) is required for maximum benefit.
Although the reported data are limited somewhat by how MDI is defined, long-term outcomes of patients with MDI are generally favorable with nonoperative treatment. Satisfactory results were reported in 29 of 33 (88%) patients with MDI by Burkhead and Rockwood.23 Children with voluntary dislocation/subluxation of the glenohumeral joint usually do well long term with no increase in osteoarthritis in adulthood and should be managed conservatively.24
Surgical intervention is limited to patients who failed an adequate trial of therapy and have continued instability. Surgery for pain alone in patients with MDI has not been shown to be effective. Operations should be avoided for patients who are unable to cooperate with therapy or who have cognitive or mental health issues that would preclude full participation in a postoperative rehabilitation program.
References
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