Shoulder dislocations
Shoulder dislocation is displacement of the humeral head from the glenoid, most often anterior after a fall or load-bearing injury with the arm held abducted and externally rotated, or posterior after a seizure or electrical injury with the arm adducted and internally rotated. Diagnosis is clinical, confirmed by radiograph, and treatment is prompt closed reduction followed by a sling, with surgery reserved for recurrent instability or an associated fracture.
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What this article covers
- Overview
The shoulder is the most frequently dislocated major joint, a consequence of the glenohumeral joint's wide range of motion and shallow, poorly constrained socket.
- Epidemiology
The shoulder accounts for the largest share of major joint dislocations seen in emergency and orthopedic practice, reflecting its inherent instability relative to other joints.
- Risk factors
A fall on an outstretched, abducted, externally rotated arm, the classic anterior-dislocation mechanism.
- Pathophysiology
Anterior dislocation: a force applied to an abducted, externally rotated arm exploits the anterior-inferior weak point of the rotator cuff, displacing the humeral head anteriorly out of the glenoid…
- Clinical features
Arm position establishes the diagnosis at the bedside: anterior dislocation presents with the arm held in slight abduction and external rotation; posterior dislocation presents with the arm held adducted and internally rotated.
- Differential diagnosis
Rotator cuff tear: acute anterior shoulder pain and weakness with abduction or external rotation after a fall on an outstretched arm, but the joint remains located, without the fixed abnormal arm…
- Diagnosis
Shoulder dislocation is a clinical diagnosis, confirmed by radiograph: the combination of a traumatic or seizure/electrical mechanism with the classic arm-position deformity establishes the diagnosis…
- Management
First, evaluate and document the neurovascular exam, specifically axillary nerve sensation and motor function, before attempting reduction.
- Complications
Recurrent dislocation and chronic glenohumeral instability, most likely in younger patients and after repeated events.
- Prognosis
Prompt reduction generally yields good functional recovery for an isolated, uncomplicated first-time dislocation.
- Prevention
Prompt seizure recognition and safe positioning during a seizure to limit the forceful muscular contraction that produces posterior dislocation.
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Related articles
- Rotator cuff syndrome
Rotator cuff syndrome spans subacromial impingement, tendinopathy, and full-thickness tear of the supraspinatus and its neighboring tendons, presenting with lateral shoulder pain worse with overhead activity and at night. Impingement is managed with activity modification, NSAIDs, physical therapy, and corticosteroid injection, while a confirmed full-thickness tear with weakness or failed conservative therapy is referred for surgical repair.
- Adhesive capsulitis
Adhesive capsulitis (frozen shoulder) is progressive fibrotic thickening of the glenohumeral joint capsule causing global loss of active and passive range of motion. It is a clinical diagnosis treated with range-of-motion physical therapy, analgesia, and intra-articular glucocorticoid injection, with capsular release reserved for cases that fail 3 to 6 months of conservative care.