Shoulder Dislocation & Instability

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For further information, see CMDT Part 41-02: Musculoskeletal Injuries of the Shoulder

Key Features

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Most dislocations (95%) are in the anterior direction
Dislocations usually are caused by a fall on an outstretched and abducted arm
Posterior dislocations are usually caused by
- Falls from a height
- Epileptic seizures
- Electric shocks
Traumatic shoulder dislocation can lead to instability
Atraumatic shoulder dislocations are usually caused by
- Intrinsic ligament laxity
- Repetitive microtrauma leading to joint instability

Clinical Findings

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Pain and apprehension with an unstable shoulder that is abducted and externally rotated
Acute traumatic dislocations
- Acute pain and obvious deformity with the humeral head dislocated anteriorly
- Patient holds the shoulder and arm in an externally rotated position
Patients with recurrent dislocations can have less pain with subsequent dislocations
Atraumatic shoulder instability
- Usually well tolerated with activities of daily living
- 'Sliding' sensation during exercises or strenuous activities such as throwing
- May be less symptomatic
- Can often undergo spontaneous reduction, with pain resolving within days after onset
See Table 41–1 for description of the apprehension test, the load and shift test, and O'Brien test

Table 41–1.Shoulder examination.

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Table 41–1. Shoulder examination.

Maneuver

Description

Inspection

Check the patient’s posture and “SEADS” (swelling, erythema, atrophy, deformity, surgical scars).

Palpation

Include important landmarks: acromioclavicular (AC) joint, long head of biceps tendon, coracoid, and greater tuberosity (supraspinatus insertion).

Range of motion testing

Check range of motion actively (patient performs) and passively (clinician performs).

Flexion

Move the arm forward as high as possible in the sagittal plane.

External rotation

Check with the patient’s elbow touching their body so that external rotation occurs predominantly at the glenohumeral joint.

Internal rotation

The patient is asked to reach the thumbs as high as possible behind the spine on each side. The clinician can record the highest spinous process that the individual can reach on each side (iliac crest = L4, inferior angle of scapula = T8).

Rotator Cuff Strength Testing

Supraspinatus (open can) test

Perform resisted shoulder abduction at 90 degrees with slight forward flexion to around 45 degrees to test for supraspinatus tendon strength (“open can” test), or with shoulder abduction at 30 degrees and flexion to 30 degrees (“empty can” test).

External rotation

The patient resists by externally rotating the arms with elbows at his or her side.

Internal rotation (lift-off test)

A positive “lift-off” test is the inability of the patient to hold his or her hand away from the body when reaching toward the small of the back. The clinician pushes the patient’s hand toward the back while the patient resists. A positive lift-off indicates subscapularis tendon insufficiency.

Internal rotation (belly-press test)

A positive “belly-press” test is the inability to hold the elbow in front of the trunk while pressing down with the hand on the belly. A positive belly-press test indicates subscapularis tendon insufficiency.

Impingement Testing

Neer impingement sign

Perform by having the clinician flex the shoulder maximally in an overhead position. The test is positive when pain is reproduced with full passive shoulder flexion. Sensitivity is 79%; specificity is 53%.

Hawkins impingement sign

Perform with the shoulder forward flexed 90 degrees and the elbow flexed at 90 degrees. The shoulder is then maximally internally rotated to impinge the greater tuberosity on the undersurface of the acromion. The test is considered positive when the patient’s pain is reproduced by this maneuver. Sensitivity is 79%; specificity is 59%.

Stability testing

Apprehension test

With persistent anterior instability or a recent dislocation, the patient feels pain or guards when the shoulder is abducted and externally rotated at 90 degrees. With posterior instability, the patient is apprehensive with the shoulder forward flexed and internally rotated to 90 degrees with a posteriorly directed force.

Load and shift test

Perform to determine shoulder instability by manually translating the humeral head anteriorly and posteriorly in relation to the glenoid. However, this test can be difficult to perform when the patient is not relaxed.

O’Brien test

Performed to rule out labral cartilage tears that often occur following a shoulder subluxation or dislocation. The test involves flexing the patient’s arm to 90 degrees, fully internally rotating the arm so the thumb is facing down (palm down), and adducting the arm to 10 degrees. Once positioned properly, the clinician applies downward force and asks the patient to resist. The test is then repeated in the same position except that the patient has his arm fully supinated (palm up). A positive O’Brien test for labral tear is pain deep in the shoulder with palm down more than the palm up.

The O’Brien test can also be used to identify AC joint pathology. The patient would typically complain equally of pain directly over the AC joint with the palm down or up.

Diagnosis

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Radiographs for acute dislocations should include anteroposterior and axillary lateral scapula (glenohumeral) views to determine the relationship of the humerus and the glenoid and to rule out fractures
Orthogonal views are used to identify a posterior shoulder dislocation
An axillary lateral view of the shoulder can be safely performed even in a patient with a painful shoulder dislocation
MRI
- Shows soft tissue injuries to the labrum
- Visualizes associated rotator cuff tears
MRI arthrograms better identify labral tears and ligamentous structures
Three-dimensional CT scans are used to determine the significance of bony loss

Treatment

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For acute dislocations
- Shoulder should be reduced as soon as possible
- The Stimson procedure is the least traumatic method
- Then, sling immobilization for 2–4 weeks along with pendulum exercises
- Early physical therapy to maintain range of motion and strengthen rotator cuff muscles
- Patients can also modify their activities to avoid active and risky sports
For traumatic incident and unilateral shoulder dislocation
- A Bankart lesion is commonly present
- Surgery is often required
For chronic, recurrent dislocations
- Physical therapy
- Regular maintenance program, consisting of scapular stabilization and postural and rotator cuff strengthening exercises
- Activities may need to be modified
- When surgery is indicated, it is more likely to be open surgery with bone augmentation than arthroscopic stabilization
For atraumatic, multidirectional, bilateral shoulder instability
- Rehabilitation is the mainstay for treatment
Inferior capsular shift surgery is rarely required

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Key Features

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