II. Epidemiology

  1. Incidence: 24 per 100,000 persons per year
    1. Most commonly dislocated joint (50% of all major joint dislocations)

III. Types: Dislocation

  1. Anterior dislocation (most common, 90% of dislocations)
    1. Humerus is displaced anteriorly relative to the glenoid cavity
    2. Results from fall on externally rotated, abducted and extended arm (throwing position)
    3. Humeral head lie may be subcoracoid (most common), subglenoid, subclavicular or intrathoracic
  2. Posterior dislocation (<4% of all Shoulder Dislocations)
    1. Large force at anterior Shoulder directed posteriorly against internally rotated arm, flexed Shoulder
    2. Often occurs secondary to Generalized Seizure (via forced internal rotation and adduction)
      1. Seizure is responsible for approximately one third of cases (remainder due to Trauma)
      2. May cause bilateral dislocation
    3. Some patients can posteriorly dislocate voluntarily
    4. Often missed on initial provider evaluation (50% of cases)
      1. Diagnosis has been delayed weeks to months in some cases with significant complications
  3. Multidirectional instability
    1. Lax joint capsule allows multidirectional dislocation
  4. Inferior dislocation (Luxatio Erecta): Rare (<0.5% of all Shoulder Dislocations)
    1. Variant of anterior dislocation
    2. Associated with Fracture, Rotator Cuff Injury and neurovascular injury (Brachial Plexus, axillary artery)
    3. Result of high energy mechanism with exaggerated abduction, tearing the inferior capsule and labrum
      1. Axial loading of a fully abducted arm OR
      2. Hyperabduction force to the arm
    4. Patient presents locked with Forearm to forehead position, unable to move the arm out of this position
      1. Arm is in fixed, abducted position overhead
      2. Humeral head palpable in the axilla
    5. Managed with Shoulder reduction using inferior dislocation specific techniques (see Shoulder reduction)
    6. Operative management indications (8% of cases)
      1. Neurovascular injury (Brachial Plexus Injury, axillary artery injury)
      2. ShoulderFracture Dislocation
      3. Unstable Shoulder requiring rotator cuff repair and capsular reconstruction
      4. Nambiar (2018) Eur J Trauma Emerg Surg 44(1): 45-51 [PubMed]

IV. Pathophysiology: Mechanism

  1. General
    1. The Shoulder joint is unstable by nature
    2. The shallow glenoid fossa articulates only 20-30% of the humeral head
    3. Requires ligamentous (e.g. labrum) and tendons (rotator cuff) for stability
  2. Young patient
    1. Direct Trauma or Sports Injury (Contact Sports, Bicycle accident)
  3. Older patient
    1. Results from fall (often with Fracture)

V. Pathophysiology: Mnemonic TUBS-AMBRI

  1. First Type of Shoulder Dislocation (TUBS)
    1. Traumatic mechanism of injury
    2. Unilateral Shoulder involvement
    3. Bankart and Hill-Sachs glenohumeral Fractures
      1. Bankart lesion (Glenoid fossa avulsion)
      2. Hill-Sachs lesion (Humeral head avulsion)
    4. Surgery often required for management
  2. Second Type of Shoulder Dislocation (AMBRI)
    1. Atraumatic mechanism
    2. Multidirectional instability
    3. Bilateral Shoulder involvement
    4. Rehabilitation as primary management
    5. Inferior Capsular shift surgery
      1. Indicated for failed conservative therapy

VI. Signs

  1. Acromion much more prominent
  2. Humeral head fullness absent under deltoid
    1. Leaves prominent cavity
    2. Dimpling at lateral Shoulder (inferior to acromion)
  3. Severe pain with any range of motion
    1. Arm "locked" in place (may be cradled by other hand)
    2. Patient refuses to move arm
  4. Anterior dislocation
    1. Affected Shoulder has squared off appearance
    2. Arm held externally rotated, and slightly abducted
    3. Anterior Shoulder appears full with anterior bulge
    4. Space below acromion appears empty
    5. Internal rotation painful
  5. Posterior dislocation
    1. Arm held in internal rotation and adduction
    2. Forearm rests on Abdomen
    3. Anterior Shoulder flat with loss of contour
    4. Prominent coracoid process anteriorly
    5. Posterior Shoulder rounded and full
    6. External rotation painful and limited
    7. Assess neurovascular structures
      1. Check axillary nerve with deltoid Sensation (lateral shoulder Sensation)
  6. Inferior dislocation (luxio erecta)
    1. Arm held fixed, abducted overhead with Forearm pronation (Luxatio Erecta)
      1. Humeral head palpable in the axilla
      2. Flexed elbow and pronated Forearm
    2. Evaluate carefully for associated neurovascular injury, Fracture or tendon/ligament injury
      1. Axillary artery injury (39% of cases)
      2. Brachial Plexus Injury (60% of cases)
      3. Labral and joint capsule injury
      4. Humerus Fracture
      5. Rotator Cuff Tear
  7. Other evaluation
    1. Evaluate for neurovascular injury with distal pulses, motor and Sensation (esp. posterior dislocation)
    2. Evaluate for Axillary Nerve Injury (shrugging Shoulder)

VII. Differential Diagnosis

  1. Acromioclavicular Separation (or AC Sprain)
  2. Distal Clavicle Fracture
  3. Humeral Neck Fracture

VIII. Imaging: Shoulder XRay

  1. Precautions: Posterior Shoulder Dislocation
    1. Easily missed on XRay since the humeral head will be roughly in proximity to glenoid (on AP film)
      1. However, Scapular Y View XRay should identify the dislocation (esp. with comparison views)
    2. Humeral head will have rounded appearance (lightbulb sign, gun barrel sign, drumstick sign)
      1. Results from internal rotation of the arm
      2. Loss of visibility of the greater tuberosity and lesser tuberosity contours
      3. Rim sign (increased distance between anterior glenoid fossa and humeral head)
      4. Decreased half moon overlap of glenoid with humeral head
    3. Consider CT Shoulder Imaging
      1. Defines articular surface defects, humeral head and glenoid Fractures not seen on xray
      2. May direct surgical management
  2. Precautions: Inferior Dislocation
    1. Humeral head is parallel to Scapular spine
    2. Consider CT Angiography for suspected associated vascular injury (axillary artery)
  3. Pre-reduction Shoulder XRay
    1. Not needed if low force mechanism with findings consistent with uncomplicated Anterior Shoulder Dislocation
      1. Especially on sideline (if no obvious signs of Fracture) or recurrent dislocator with atraumatic mechanism
      2. Early relocation without delay allows for an easier relocation prior to development of spasm
    2. Imaging Indications
      1. Age over 40 years or other risks for pathologic Fracture
      2. First-time Shoulder Dislocation
      3. Traumatic mechanism suggests risk for more significant injury (suspected Fracture)
      4. Unclear diagnosis
      5. Emond (2004) Acad Emerg Med 11(8): 853-8 [PubMed]
  4. Post-reduction Shoulder XRay
    1. Obtain in all cases
  5. Standard Views
    1. Anteroposterior (AP)
    2. Lateral Shoulder XRay (Transaxillary lateral often easiest)
    3. Scapular Y Xray
  6. Other XRay Views
    1. West Point View (glenoid cavity)
    2. Stryker View (Hill-Sachs Fracture)
  7. References
    1. Mallon (2013) Shoulder disorders, EM Bootcamp, Las Vegas

IX. Management

  1. Acute Management
    1. See Shoulder Dislocation Management
      1. Includes Post-Reduction Management of Shoulder Dislocation (e.g. sling, range of motion)
    2. Do not attempt to reduce a chronic Shoulder Dislocation present for >3-4 weeks (>1 week in elderly)
      1. Prolonged dislocations form adhesions between Humerus and axillary artery
      2. Risk of axillary artery rupture on relocation maneuvers
      3. Relocation should be by orthopedic surgery typically in the operating room
      4. Herbert and Webley in Herbert (2015) EM:RAP 15(3): 1
      5. Verhaegen (2012) Acta Orthop Belg 78(3): 291-5 [PubMed]
      6. Sahajpal (2008) J Am Acad Orthop Surg 16(7): 385-98 [PubMed]
    3. Emergent orthopedic Consultation indications
      1. Neurovascular Injury
      2. Inferior Shoulder Dislocation
      3. Concurrent Proximal Humerus Fracture (e.g. surgical neck Fractures)
      4. Bankart fracturs >20% of inferior glenoid
      5. Articular defects >25% in Posterior Shoulder Dislocations
      6. Failed emergency department reduction
        1. Soft tissue (long head biceps, subscapularis tendon) may block Shoulder relocation
  2. Chronic Management and prevention of recurrence
    1. See Shoulder Instability

X. Course: Primary Dislocation

  1. Anterior Shoulder Dislocation in under 25 years (even first episode)
    1. Surgical management results in fewer future dislocations
    2. Surgery also offers less risk of longterm instability and Traumatic Arthritis
  2. Age under 30 years
    1. Recurrence rate: 50%
    2. Surgery indicated for recurrent dislocation or Hill-Sachs lesion
      1. Restrict rotation
      2. Reinforce joint capsule
  3. Age over 40 years
    1. Shoulder stiffness common
    2. Dislocation recurs less frequently
  4. Age over 50 years
    1. Risk of concurrent Rotator Cuff Rupture: 50%

XI. Complications

  1. Hill-Sachs Deformity (35-40% of cases)
    1. Cortical depression of humeral head (where it contacted the glenoid rim)
  2. Rotator Cuff Injury
    1. Age over 40 years old predicts Rotator Cuff Tear in 35% of dislocation cases
    2. Greater tuberosity Fracture predicts Rotator Cuff Tear in 40% of dislocation cases
    3. Axillary Nerve Injury predicts Rotator Cuff Tear in 100% of dislocation cases
  3. Neurovascular injury (esp.in elderly, inferior dislocation)
    1. Axillary Nerve Injury
    2. Brachial Plexus Injury
  4. Shoulder Labral Tear
    1. Anterior glenoid Labral Tear is most common
  5. Shoulder Instability
    1. Recurrent Shoulder Dislocation or Shoulder Subluxation
  6. Missed Posterior Shoulder Dislocation
    1. Humeral Head Avascular Necrosis
    2. Glenohumeral joint degeneration, articular cartilage injury and Arthropathy
    3. Chronic Shoulder Pain and Disability
  7. Adhesive Capsulitis
    1. Highest risk in Diabetes Mellitus and older patients
    2. Early Shoulder mobilization is preventive

XII. References

  1. Chan and Huang (2022) Crit Dec Emerg Med 36(2): 16-7
  2. Dolbec (2019) Crit Dec Emerg Med 33(1): 17-25
  3. Kiel and Koneru (2019) Crit Dec Emerg Med 33(9): 17-27
  4. Huang (2021) Crit Dec Emerg Med 34(7): 24-5
  5. Hendey (2000) Ann Emerg Med 36:108-13 [PubMed]
  6. Hovelius (1996) J Bone Joint Surg 78-A: 1677-84 [PubMed]
  7. Monica (2016) Am Fam Physician 94(2): 119-27 [PubMed]

Images: Related links to external sites (from Bing)

Related Studies

Ontology: Shoulder Dislocation (C0037005)

Definition (MSH) Displacement of the HUMERUS from the SCAPULA.
Concepts Injury or Poisoning (T037)
MSH D012783
ICD9 831
ICD10 S43.0
SnomedCT 125615005, 417076003, 269325002, 208781006, 157259008
English Dislocations, Shoulder, Shoulder Dislocation, Shoulder Dislocations, Dislocation, Shoulder, Dislocation of shoulder NOS, Dislocation, Glenohumeral, Dislocations, Glenohumeral, Glenohumeral Dislocations, Glenohumeral Dislocation, Traumatic dislocation of shoulder region, dislocated shoulder, dislocation of shoulder (diagnosis), dislocation of shoulder, dislocation of shoulder (physical finding), Shoulder Dislocation [Disease/Finding], Dislocation of shoulder joint [glenohumeral joint], dislocation shoulder, dislocations shoulder, shoulder dislocation, Dislocation;shoulder, dislocate shoulder, dislocated shoulders, shoulder dislocations, of shoulder dislocation, shoulder dislocated, Dislocation of shoulder, Dislocation of shoulder NOS (disorder), Shoulder - dislocated, Shoulder luxation, Scapulohumeral joint luxation, Traumatic dislocation of shoulder region (diagnosis), shoulder region dislocation traumatic, Shoulder joint--Dislocation, Dislocated shoulder, Dislocation of shoulder region, Traumatic dislocation of shoulder region (disorder), dislocation; glenoid, dislocation; shoulder, glenoid; dislocation, shoulder; dislocation, Dislocated Shoulder, dislocation; glenohumeral, glenohumeral; dislocation, Dislocation of shoulder joint, Shoulder dislocation, Dislocation of glenohumeral joint, Dislocation of shoulder joint (disorder), dislocation of the shoulder
Dutch ontwrichting van schouder, ontwrichte schouder, schouderontwrichting, glenoïdaal; luxatie, luxatie; glenoïdaal, luxatie; schouder, schouder; luxatie, Luxatie van schoudergewricht, glenohumeraal; luxatie, luxatie; glenohumeraal, Luxatie, schouder-, Schouderluxatie
French Epaule luxée, Luxation gléno-humérale, Luxation glénohumérale, Luxation de l'épaule
German luxierte Schulter, Luxation der Schulter, Schulterluxation, Glenohumerale Luxation, Schulterausrenkung, Schultergelenkluxation, Schulterverrenkung, Luxatio humeri, Luxation des Schultergelenkes
Italian Spalla lussata, Lussazione glenomerale, Lussazione della spalla
Portuguese Luxação do ombro, Ombro luxado, Luxação Glenoumeral, Luxação do Ombro
Spanish Luxación de hombro, Luxación Glenohumeral, luxación de hombro, luxación de articulación glenohumeral, luxación de articulación del hombro, luxación de articulación de hombro (trastorno), luxación de articulación de hombro, luxación de articulación del hombro (trastorno), luxación traumática de región de hombro, luxación traumática de la región del hombro (trastorno), luxación traumática de la región del hombro, luxación traumática de región de hombro (trastorno), luxación de hombro, SAI (trastorno), luxación de hombro, SAI, Luxación del Hombro
Japanese 肩の脱臼, 脱臼肩, カタノダッキュウ, ダッキュウカタ, ダッキュウケン, 肩脱臼, 肩関節脱臼(カタカンセツダッキュウ), カタカンセツダッキュウ, 肩関節脱臼
Swedish Skulderdislokation
Czech rameno - dislokace, Vymknuté rameno, Vykloubení ramene, Vymknutí ramene, luxace ramene, vykloubení ramenního kloubu, luxace ramenního kloubu, dislokace ramene, rameno - luxace, vykloubené rameno
Finnish Olkaluun sijoiltaanmeno
Korean 어깨관절의 탈구
Polish Zwichnięcie barku
Hungarian Luxált váll, Váll luxatiója, Váll luxatio
Norwegian Skulderen ut av ledd, Skulderluksasjon, Glenohumeraldislokasjon, Skulder ut av ledd, Skulderdislokasjon, Dislokasjon av skulder

Ontology: Anterior dislocation of shoulder joint (C0347738)

Concepts Injury or Poisoning (T037)
SnomedCT 208756008, 263021005
English Ant disloc of shoulder joint, Anterior dislocation shoulder, anterior dislocation shoulder, anterior shoulder dislocation, anterior dislocations shoulder, Anterior dislocation of shoulder joint (diagnosis), shoulder region dislocation anterior, Anterior dislocation of shoulder, Anterior dislocation of shoulder joint, Anterior dislocation of shoulder joint (disorder)
Spanish luxación anterior de articulación de hombro (trastorno), luxación anterior de la articulación del hombro, luxación anterior de la articulación del hombro (trastorno), luxación anterior de articulación de hombro

Ontology: Posterior dislocation of shoulder joint (C0347739)

Concepts Injury or Poisoning (T037)
SnomedCT 208757004, 263022003
English Post disloc of shoulder joint, Posterior dislocation shoulder, posterior dislocation of shoulder joint, shoulder posterior dislocation, posterior shoulder dislocation, shoulder region dislocation posterior, Posterior dislocation of shoulder joint (diagnosis), Posterior dislocation of shoulder, Posterior dislocation of shoulder joint, Posterior dislocation of shoulder joint (disorder)
Spanish luxación posterior de hombro (trastorno), luxación posterior de hombro

Ontology: Luxatio erecta (C0559395)

Concepts Injury or Poisoning (T037)
SnomedCT 281502009
English Luxatio erecta (diagnosis), shoulder region dislocation luxatio erecta, Luxatio erecta, Luxatio erecta (disorder)
Spanish luxación erecta (trastorno), luxación erecta

Ontology: Inferior dislocation of humerus (C0840597)

Concepts Injury or Poisoning (T037)
ICD10 S43.03
English Inferior dislocation of humerus, inferior dislocation of humerus, inferior dislocation of humerus (diagnosis)