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Updated: Apr 12 2022

Avascular Necrosis of the Shoulder

Images 5 avn.jpg 2 avn.jpg 3 avn.jpg mri.jpg
  • summary
    • Avascular necrosis of the shoulder is a condition characterized by interruption of blood supply to the humeral head which may lead to humeral head sclerosis and subchondral collapse. 
    • Diagnosis is made radiographically with orthogonal radiographs of the shoulder in moderate/late disease. MRI may be needed for detection of early or subclinical avascular necrosis.
    • Treatment may be observation for very early and minimally symptomatic disease. Surgical management is indicated for progressive symptoms in the setting of moderate to advanced disease.
  • Etiology
    • Pathophysiology
      • pathoanatomy
        • decreased blood supply to humeral head leading to death of cells in bony matrix.
        • bone is resorbed and remodeled, causing subchondral bone collapse and may lead to joint incongruity and arthritic changes
      • etiology similar to hip
        • Remember ASEPTIC mneumonic
          • Alcohol, AIDS
          • Steroids (most common), Sickle, SLE
          • Erlenmeyer flask (Gaucher’s)
          • Pancreatitis
          • Trauma
          • Idiopathic/ Infection
          • Caisson’s (the bends)
        • may be atraumatic
        • posttraumatic
          • four-part fracture-dislocations approach 100% AVN
          • displaced four-part fractures ~45% AVN
          • valgus impacted four-part ~11% AVN
          • three-part ~14% AVN
  • Anatomy
    • Blood supply
      • Humeral head
        • ascending branch of anterior humeral circumflex artery and arcuate artery
          • provides blood supply to humeral head
          • vessel runs parallel to lateral aspect of tendon of long head of biceps in the bicipital groove
            • beware not to injure when plating proximal humerus fractures
          • arcuate artery is the interosseous continuation of ascending branch of anterior humeral circumflex artery and penetrates the bone of the humeral head
          • provides 35% of blood supply to humeral head
        • posterior humeral circumflex artery
          • most current literature supports this as providing the main blood supply to humeral head
          • provides 65% of blood supply
  • Classification
      • Cruess Classification (stages)
      • Radiographic findings
      • Treatment
      • StageI
      • Normal x-ray, changes on MRI only
      • Core decompression
      • Stage II
      • Sclerosis (wedged, mottled) Osteopenia
      • Core decompression
      • Stage III
      • Crescent sign indicating a subchondral fracture
      • Resurfacing or hemiarthroplasty
      • Stage IV
      • Flattening and collapse
      • Resurfacing or hemiarthroplasty
      • Stage V
      • Degenerative changes extend to glenoid
      • Total shoulder arthroplasty
  • Presentation
    • Symptoms
      • insidious onset of shoulder pain
        • often without a clear inciting event
      • pain, loss of motion, crepitus, and weakness
    • Physical exam
      • limited range of motion
      • crepitus
      • weakness of the rotator cuff and deltoid muscles
  • Imaging
    • Radiographs
      • recommended views
        • five views of shoulder (shown best in neutral rotation AP)
      • findings
        • no findings on radiograph at onset of disease process
        • osteolytic lesion develops on radiograph demonstrating resorption of subchondral necrosis
          • most common initial site is superior middle portion of humeral head
        • crescent sign demonstrates subchondral collapse
        • may progress to depression of articular surface and consequent arthritic changes.
    • MRI
      • preferred imaging modality
        • ~100% sensitivity in detection
      • will demonstrate edema at the site of subchondral sclerosis
  • Treatment
    • Nonoperative
      • pain medications, activity modification, physical therapy
        • indications
          • first line of treatment
        • technique
          • physical therapy
            • restrict overhead activity and manual labor
    • Operative
      • core decompression + arthroscopy (confirm integrity of cartilage)
        • indications
          • early disease (precollapse Cruess Stage I and II)
      • humeral head resurfacing
        • indications
          • Stage III disease with focal chondral defects, and sufficient remaining epiphyseal bone stock for fixation.
      • hemiarthroplasty
        • indications
          • moderate disease (Cruess Stage III and IV)
      • total shoulder arthroplasty
        • indications
          • advance stage (Cruess V)
  • Prognosis
    • Related to stage of disease
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