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Shoulder Dislocation & Instability

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

Key Features

  • 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

  • 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

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

External rotation

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

Internal rotation

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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

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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

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

Internal rotation (lift-off test)

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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)

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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 ...

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