AC Dislocation

Aka: AC Dislocation, Acromioclavicular Dislocation, AC Separation, Acromioclavicular Separation, Acromioclavicular Ligament Sprain, Acromioclavicular Joint Injury

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II. Definitions

  1. Acromioclavicular Dislocation
    1. Acromioclavicular joint dislocation or "Separation"

III. Epidemiology

  1. Ages to 20 to 49 years old
  2. More common in males
  3. More common in athletes, esp. Contact Sports (football, hockey)

IV. Mechanism

  1. Fall on an outstretched hand
  2. Direct Trauma
    1. Top of Shoulder or
    2. Shoulder or acromion with arm adducted

V. Grading: AC joint dislocation (Rockwood Classification)

  1. Incomplete dislocation (Types I to II, 70-90% of cases, non-operative, conservative management)
    1. Type I: Simple AC joint Contusion or sprain, no clavicle displacement
    2. Type II: AC joint ligament rupture, slight clavicle elevation (<25%)
  2. Complete dislocation (Types III to V)
    1. Type III: Rupture of coracoclavicular ligaments, moderate clavicle elevation (25-75%)
    2. Type IV: Joint posteriorly displaced (uncommon), into the trapezius Muscle
    3. Type V: Overlying Muscle penetrated (uncommon), distal clavicle elevated 100-300%
    4. Type VI: Clavicle displaced behind biceps (rare), associated with Rib Fractures and neurovascular injury

VI. Symptoms

  1. Tenderness and swelling over AC joint
  2. Pain on lifting arm

VII. Signs

  1. See Hand Neurovascular Exam
  2. Lateral or distal clavicle elevated
    1. Deformity if Grade III or higher
  3. Provocative Maneuvers eliciting pain
    1. Downward traction on arm
    2. Shoulder Crossover Maneuver (cross-body adduction of arm)

VIII. Differential Diagnosis

  1. Rotator Cuff Tear
  2. Acromioclavicular Osteoarthritis
    1. Older patients, with non-Traumatic pain

IX. Imaging: XRay

  1. Views
    1. Anteroposterior View (with other side for comparison)
      1. Highest yield initial XRay
    2. Zanca View (10-15 degrees cephalic tilt)
    3. Axillary View
      1. May better identify posterior AC Dislocations (Type IV)
    4. Cross Body Adduction View
      1. Hand on the affected side reaches across the chest to grasp the opposite Shoulder
      2. Increases clavicle elevation in coracoclavicular ligament injury
    5. Internal rotation of affected arm
      1. Consider in Type III rotation
  2. Indications
    1. Differentiate incomplete from complete AC Dislocation
    2. Evaluate for Clavicle Fractures and other complications
  3. Obtain opposite side for comparison if laxity is present
    1. Ibrahim (2015) Injury 46(10): 1900-5 [PubMed]
  4. Weighted views are no longer indicated
    1. Diagnosis is clinical and XRay may be diagnostic with step-off seen
      1. Comparison films with opposite side are still helpful
    2. Old protocol used XRay taken with 10 kg weights hanging from each arm
      1. Measured coracoid process to clavicle distance
      2. Discrepancy between sides suggested AC Dislocation
  5. Advanced Imaging (e.g. CT Chest) Indications
    1. Type IV to VI AC Dislocations
    2. Neurovascular compromise

X. Management

  1. Orthopedic referral for Type III to VI AC Separations
  2. Symptomatic relief
    1. Immobilize with sling for 3 days depending on pain (limiting to short duration is best)
      1. Avoid sling use >1-2 weeks to prevent Frozen Shoulder
    2. See RICE-M
    3. Analgesics as needed
      1. Clavicle tip often prominent, but usually painless
    4. Anticipate symptom duration based on type of AC Separation
      1. Type I: 1-3 weeks of symptoms
      2. Type II: 4-6 weeks of symptoms
      3. Type III: 3 months of symptoms
        1. May require surgical management in active patients (athletes, laborers, military)
        2. Good outcome in 80% without surgery
      4. Type IV to VI: Surgical management
  3. Active range of motion of strengthening (non-surgical, Type I to III cases)
    1. Begin range of motion as soon as possible (for non-surgical cases)
    2. See Shoulder Range of Motion Exercises
    3. See Shoulder Strengthening Exercises
    4. Physical therapy to optimize range of motion, Shoulder strength and Scapular stability
    5. Return to sport when pain free activity that matches the unaffected side
  4. Other Non-invasive Measures in Refractory Pain Cases
    1. Acromioclavicular Joint Injection
      1. Controversial Corticosteroid use (risk of Soft Tissue Injury)
  5. Surgery Indications
    1. Type 4 to 6 AC Dislocation
    2. Type 3 AC Dislocation if physically active or symptoms persist 3-6 months

XI. Management: Taping Technique (consider in Wilderness)

  1. Realignment
    1. Examiner 1 pushes down on clavicle
    2. Examiner 2 pushes up on upper arm from elbow
  2. Taping technique
    1. Start Tape from just medial and superior to nipple
      1. Extend tape over Shoulder and onto mid Scapula
      2. Repeat with overlapping strips moving laterally
    2. Secure above taping with tape over ends
    3. Start tape perpendicularly to above
      1. Run over top of Shoulder from medial to lateral

XII. Complications

  1. Clavicle Fracture (lateral third)
  2. Coracoid process Fracture
  3. Sternoclavicular Dislocation
  4. Brachial Plexus Injury (rare)
  5. Acromioclavicular joint degenerative changes (AC Arthritis)

XIII. References

  1. Dolbec (2019) Crit Dec Emerg Med 33(1): 17-25
  2. Kiel and Koneru (2019) Crit Dec Emerg Med 33(9): 17-27
  3. Lin and Silverio in Herbert (2018) EM:Rap 18(1):14-16
  4. Wirth in Greene (2001) Musculoskeletal Care, p.115-7
  5. Monica (2016) Am Fam Physician 94(2): 119-27 [PubMed]

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