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Introduction
  • Most common condition of the AC joint
  • AC joint arthritis is caused by transmission of axial large loads through a small contact area resulting in repetitive microtrauma (same mechanism as distal clavicle osteolysis)
  • Epidemiology
    • demographics
      • more common with age but can occur by second decade of life
      • more common in weight-lifters and other sports
    • risk factors
      • trauma
      • post-traumatic (i.e. clavicle fractures, AC instability)
      • distal clavicle osteolysis 
      • inflammatory arthropathy (i.e. RA)
      • post-infectious arthropathy (i.e. septic arthritis)
      • Commonly associated with individuals who engage in constant heavy ocerhead activities
        • especially in weight-lifters and overhead throwing athletes
Anatomy
  • Acromioclavicular Joint Anatomy
    • diarthrodial joint
      • articulation scapula to clavicle
      • contains a fibrocartilaginous intraarticular disc analogous to the meniscus of the knee
    • Small articular surface area with relatively high axial and rotational loads leads to high contact forces across AC joint
      • Exacerbated by articular disk degeneration and olbquie joint surface orientation
    • Ligaments
      • acromioclavicular (AC) ligaments
        • provide anterior-posterior stability
          • posterior and superior AC ligaments are most important for stability
      • coracoclavicular (CC) ligaments
        • provide superior-inferior stability
Presentation
  • Symptoms
    • activity related superior shoulder pain 
      • with overhead activity
      • with cross body arm adduction
      • with O'Brien's active compression test (at 90 degrees forward flexion)
      • exacerbated with pressing motion (i.e. bench press, push-up) and leaning on affected side (i.e. while sleeping)
  • Physical examination 
    • palpation
      • pain with direct palpation of AC joint 
      • prominence of the distal clavicle (osteophytes)
    • provocative tests
      • pain with cross body adduction test  
Imaging
  • Radiographs 
    • recommended views
      • best evaluated using Zanca view (15° cephalic tilt) 
    •  Findings
      • osteophytes and joint space narrowing 
      • distal clavicle osteolysis
      • imaging findings do not always correlate with patient symptoms (often present on radiographs without clinical signs or symptoms)
  • MRI 
    • increased signal and edema in AC joint 
    • visualize associated pathology (i.e. rotator cuff, long head of biceps tendon)
Treatment
  • Nonoperative
    • activity modification and physical therapy
      • first line of treatment
      • avoid aggravating activity such as pushing/pressing activities
      • physical therapy should focus on strengthening and stretching of shoulder girdle
    • AC joint injection with corticosteriods 
      • can be both diagnostic and therapeutic modality
      • access to the AC joint is challenging
      • AC joint injections often miss the joint
        • ultrasound improves accuracy of injection
      • most patients do not experience long term relief after injections
  • Operative
    • arthroscopic vs. open distal clavicle resection (Mumford procedure) 
      • indications
        • severe symptoms that have failed nonoperative treatment
      • outcomes
        • open vs. arthroscopic based on surgeon preference and comfort
          • arthroscopic resection has the advantage of allowing evaluation of the glenohumeral joint and treatment of any associated injuries (otator cuff, long head of biceps and glenoid labrum) 
          • can combine diagnostic arthroscopy with open distal clavicle resection
          • open procedures require meticulous repair of deltotrapezial fascia
Techniques
  • Arthroscopic distal clavicle resection
    • should only resect 0.5-1cm of distal clavicle
Complications
  • AC joint instability
    • anterior-posterior instability
      • can be due to aggressive surgical distal clavicle resection ( >1-1.5cm)
      • aggressive debridement sacrificing posterior and superior AC ligaments 
    • superior-posterior instability
      • usually iatrogenic due to aggressive surgical resection compromising coracoclavicular ligaments
  • Persistent pain
    • most commonly due to incomplete resection of distal clavicle
      • posterior-superior area of the distal clavicle 
  • Heterotopic ossification
  • Deltoid dehiscence
    • inadequate deltotrapezial fascia repair after open distal clavicle resection
 

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Questions (1)

(SBQ07SM.12) Your partner performs distal clavicle excisions through an open approach while you prefer to use an arthroscopic approach. He notes that the literature shows both techniques have similar results with the exception of which of the following benefits of an arthroscopic approach? Review Topic

QID: 1397
1

Ability to evaluate the glenohumeral joint

81%

(541/666)

2

Preservation of the coracoclavicular ligaments

5%

(31/666)

3

Preservation of the inferior acromioclavicular ligaments

4%

(25/666)

4

Lower complication rate

7%

(46/666)

5

Decreased surgical time

3%

(20/666)

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