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Acromio-Clavicular Injuries (AC Separation)

Topic updated on 02/12/16 10:29am
Introduction 
  • Epidemiology
    • incidence
      • Common injury making up 9% of shoulder girdle injuries
    • demographics
      • more common in males
  • Pathophysiology
    • mechanism
      • direct blow to the point of the shoulder
      • seen while falling onto the shoulder
Anatomy
  • AC Joint
    • anatomy
      • the AC joint is a diarthrodial joint 
    • stability and ligaments
      • acromioclavicular ligament
        • provides horizontal stability
        • has superior, inferior, anterior, and posterior component
      • coracoclavicular ligaments (trapezoid and conoid)
        • provides vertical stability
        • trapezoid insert 3 cm from end of clavicle
        • conoid inserts 4.5 cm from end of clavicle in the posterior border
        • base of coracoid fracture can mimic a CC ligament disruption
    • capsule, deltoid and trapezius act as additional stabilizers
  • Complete AC joint anatomy 
Presentation
  • Symptoms
    • pain
  • Physical exam
    • palpate for lateral clavicle or AC joint tenderness
    • observe for abnormal contour of the shoulder compared to contralateral side
    • check for stability
      • AP stability assesses AC ligaments
      • vertical stability assesses CC ligaments
Imaging
  • Radiographs
    • bilateral AP
      • compare displacement to contralateral side
        • measured as distance from top of coracoid to bottom of clavicle
      • 1/3 penetration on AP to visualize AC joint
    • axillary lateral 
      • required to diagnose Type IV (posterior)
    • zanca view 
      •  performed by tilting the x-ray beam 10° to 15° toward the cephalic direction and using only 50% of the standard shoulder anteroposterior penetration strength. q
    • stress views 
      • no longer used
Classification

Rockwood Classification of AC Joint Injuries
 
AC lig.
CC lig.
Displacement / Radiographs
Tx
Illus.
Xray
Type I
sprain
normal
none
sling
 
Type II
torn
sprain
AC joint is disrupted with a slight vertical separation and there is a slight increase in the CC interspace of <25%
sling
 
Type III
torn
torn
CC distance of 25-100% of other side
controversial
Type IV
torn
torn
lateral end of the clavicle is displaced posterior through trapezius as seen on the axillary X-ray
surgery
 
Type V
torn
torn
CC distance > 100% of other side (usually associated with rupture of deltotrapezial fascia, resulting in subcutaneous distal clavicle)
surgery
Type VI
torn
torn
rare injuries with the distal clavicle lying either in a subacromial or subcoracoid position (infero-lateral under conjoined tendon)
surgery
 


Treatment
  • Nonoperative
    • ice, rest and sling for 3 weeks 
      • indications
        • Type I and II 
        • Type III in most individuals
      • rehab
        • early ROM
        • regain functional motion by 6 weeks
        • return to normal activity at 12 weeks
      • complications
        • AC joint arthritis
        • chronic subluxation and instability
  • Operative
    • ORIF or ligament reconstruction
      • indications
        • Type III in laborers and elite athletes
        • Type IV
        • Type V
        • Type VI
      • contraindications
        • patient unlikely to comply with postoperative rehabilitation
        • skin problems over fixation approach site
      • rehabilitation
        • sling immobilization without abduction for 6 weeks
        • no shoulder ROM for 6 weeks
        • generally return to full activity after 6 months 
Surgical Techniques
  • ORIF with CC screw fixation 
    • approach
      • proximal aspect of anterolateral approach to the shoulder
    • technique
      • superior to inferior screw from distal clavicle into coracoid
    • pros & cons
      • rigid internal fixation
      • danger of screw being too long and damage to critical structure below coracoid
    • complications
      • hardware irritation or failure
  • ORIF with CC suture fixation
    • approach 
      • proximal aspect of anterolateral approach to the shoulder
    • technique
      • suture placed either around or through clavicle and around the base of the coracoid
      • can also use suture anchors for coracoid fixation
    • pros & cons
      • no risk of hardware failure or migration
      • suture not as strong as screw fixation
      • requires careful suture passage inferior to coracoid due to proximity of crucial neurovascular structures
    • complications
      • suture erosion causing distal third clavicle fracture
  • ORIF with hook plate 
    • approach
      • exposure of distal and middle clavicle
    • technique
      • use of standard hook plate over superior distal clavicle
    • pros & cons
      • rigid fixation
      • generally require second surgery for plate removal
    • complications
      • high rate of acromial erosion with hook plate
  • CC ligament reconstruction (Modified Weaver-Dunn)
    • approach
      • proximal aspect of anterolateral approach to the shoulder
      • arthroscopic technique also described  
    • technique
      • distal clavicle excision 
      • transfer of coracoacromial ligament to the distal clavicle to recreate CC ligament
      • combined with internal fixation
    • pros & cons
      • coracoacromial ligament only 20% as strong as normal CC ligament
      • lack of internal fixation risks failure of soft tissue repair
  • CC ligament reconstruction with free tendon graft  
    • approach
      • proximal aspect of anterolateral approach to the shoulder
      • wrist incision for palmaris harvest
    • technique
      • figure-of--eight passage of graft from distal clavicle to coracoid
      • reinforce with internal fixation
    • pros & cons
      • graft reconstruction more closely recreates strength of native CC ligament
      • standard risks of allograft use or autograft harvest
      • lack of internal fixation risks failure of soft tissue repair
  • Primary AC joint fixation
    • approach
      • can be done percutaneously
    • technique
      • smooth wire or pin fixation directly across AC joint
    • pros & cons
      • hardware irritation
    • complications
      • high incidence of pin migration 
      • generally not performed due to high complication rates

 

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Qbank (5 Questions)

TAG
(OBQ09.272) A 58-year-old right-hand dominant accountant falls off a bicycle 4 days ago and injured his left non-dominant shoulder. A radiograph is shown in Figure A. The axillary radiograph shows no antero-posterior translation. What is the most appropriate next step in treatment? Topic Review Topic
FIGURES: A          

1. Coracoclavicular ligament reconstruction
2. Acromioclavicular capsular reconstruction
3. Sling and early ROM exercises
4. Arthroscopic distal clavicle excision
5. Weaver-Dunn procedure

PREFERRED RESPONSE ▶
TAG
(OBQ08.7) For Grade III AC joint separations, surgical treatment results in which of the following when compared to non-operative management? Topic Review Topic

1. Faster return to play
2. Increased range of motion
3. Increased functional rotator cuff strength
4. Decreased funtional rotator cuff strength
5. Higher complication rate

PREFERRED RESPONSE ▶
TAG
(OBQ08.203) A football player sustains a suspected shoulder separation. In addition to a true AP and an axillary lateral, which of the following additional radiographic views is most appropriate to evaluate the AC joint? Topic Review Topic

1. Stryker notch view
2. West Point view
3. Supraspinatus outlet view
4. Velpeau view
5. Zanca view

PREFERRED RESPONSE ▶
TAG
(OBQ05.251) What is the preferred treatment for a symptomatic acute acromioclavicular separation where there is a 20% increase in the coracoclavicular distance on AP radiograph compared to the opposite uninjured side? Topic Review Topic

1. Anatomic coracoclavicular ligament reconstruction
2. Acute repair of acromioclavicular capsule
3. Sling followed by early physical therapy
4. Reduction and retrograde pinning of the acromioclavicular joint
5. Distal clavicle excision

PREFERRED RESPONSE ▶



Videos

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