Morning Report: Acromioclavicular (AC) joint dislocations

By Jaime Moran MD, PGY-3

Edited by Dr. deSouza

Acromioclavicular joint dislocations: the “Separated” shoulder

EPIDEMIOLOGY & MECHANISM OF INJURY

  • 9-12% of shoulder girdle injuries
  • More common in males
  • Usually results as a direct blow to the shoulder; less commonly fall onto an outstretched arm.
    • Most commonly falling onto the shoulder while the arm is adducted to the side.

ANATOMY

  • Acromioclavicular joint: stabilized by 2 ligaments
    • Acromioclavicular (AC) ligament provides horizontal stability; AC joint width is normally <3mm
    • Coracoclavicular (CC) ligaments (trapezoid and conoid) provide vertical stability; CC joint distance is normally <5mm

PHYSICAL EXAM

  • Tenderness over the AC joint
  • In cases of significant ligamentous disruption, the distal clavicle may be superiorly displaced and be seen as a deformity at the top of the shoulder.

  • AC Compression test:
    • AC joint cross-body adduction
    • Pain elicited by passively adducting the patient’s arm, thereby compressing the AC joint

IMAGING

  • Routine shoulder XR
  • Consider different views:
    • Bilateral AP to compare displacement to contralateral side
    •  Axillary lateral view is required to diagnose Type IV injury
    • Zanca view – tilt the x-ray beam 10-15O towards the head to avoid superimposing the scapular spine

ROCKWOOD CLASSIFICATION: 6 Types

Type

AC

CC

Displacement / XRs

Tx

I = sprain

Sprain

Intact

None

Sling 1-2 weeks; early ROM

II = subluxation

Torn

Sprain

Slight elevation of distal clavicle; CC distance <25%

Sling; ortho referral

III = dislocation

Torn

Torn

Elevated distal clavicle; increased CC distance 25-100%

Conservative v surgery?

IV = displacement

Torn

Torn

Posterior displacement of distal clavicle through the trapezius

Surgery

V = displacement

Torn

Torn

Superior displacement of distal clavicle; CC distance > 100%; disruption of muscular and fascial attachments of distal clavicle

Surgery

VI = displacement

Torn

Torn

Inferior displacement of distal clavicle into subacromial or subcoracoid position; Rare

Surgery




TREATMENT

  • Type I
    • Sling, RICE, early ROM
  • Type II
    • Sling until pain resolves
    • Early ROM (helps prevent development of adhesive capsulitis)
    • PT and rehab
    • Avoid heavy lifting and contact sports for 3 mos. (while the ligaments heal so as not to convert the injury into a complete ligamentous tear)
  • Type III
    • Controversial – immobilization v surgery?
    • Bone Joint J 2013;95-B:1595–1602.
      • Systematic review
      • 28 studies – meta-analyses, systematic reviews, RCTs, case series
      • Limited evidence; most of the studies include heterogenous populations, different surgical techniques, and varying severities and chronicity of injury.
      • Conclusion: operative management results in better cosmetic and radiological results and similar functional outcomes, at the expense of longer time off work and increased complication rates. HOWEVER the lack of high-quality evidence makes it difficult to draw conclusions from this study.
    • Sling
    • Ortho referral
  • Types IV – VI
    • Acute management with a sling
    • Definitive treatment is surgical fixation

REFERENCES

  1. Acromioclavicular joint injuries (“separated” shoulder). Uptodate. Accessed on 02/04/16 via http://www.uptodate.com/contents/acromioclavicular-joint-injuries-separated-shoulder?source=search_result&search=ac+joint+separation&selectedTitle=1~150.
  2. Acromioclavicular Injuries. Orthobullets. Accessed on 02/04/26 via http://www.orthobullets.com/sports/3047/acromio-clavicular-injuries-ac-separation.
  3. Modi CS. Controversies relating to the management of acromioclavicular joint dislocations. Bone Joint J 2013;95-B:1595–1602.
  4. Rivers, C. 2011. “Shoulder Dislocations and Ligamentous Tears.” In Preparing for the Written board Exam in Emergency Medicine. 6th Edition. Ohio ACEP. 411-412.
  5. Simon R, Sherman S. 2011. “Shoulder”. In Emergency Orthopedics. 6th Edition. McGraw-Hill. 338-340.
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Brian

Kings County Hospital | SUNY Downstate Emergency Medicine Resident -Clinical Monster Webmaster

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