http://upload.orthobullets.com/topic/3060/images/stage 5 avn.jpg
http://upload.orthobullets.com/topic/3060/images/cruess classification.jpg
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Introduction
  • A condition caused by interruption of blood supply to humeral head
  • 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), SickleSLE
        • 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
  • Prognosis
    • related to stage of disease
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
      • posterior humeral circumflex artery
        • most current literature supports this as providing the main blood supply to humeral head  
Classification
 
Cruess Classification (stages)
Stage I Normal x-ray. Changes on MRI

Stage II Sclerosis (wedged, mottled), osteopenia
Stage III Crescent sign indicating a subchondral fracture
Stage IV Flattening and collapse
Stage V Degenerative changes extend to glenoid  
 
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  
      • indications
        • early disease (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)
 

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Questions (2)

(OBQ11.78) A 66-year-old male presents with a three-month history of increasing right shoulder pain. He denies any trauma or prior shoulder problems, and has good rotator cuff strength. His medical history is significant for Crohn's disease which is controlled medically with prednisone therapy during flares. A current MRI image of his shoulder is shown in Figure A. What is the most likely diagnosis? Review Topic

QID:3501
FIGURES:
1

Gaucher disease

0%

(2/1798)

2

Osteoarthritis

0%

(4/1798)

3

Chronic rotator cuff tendinopathy

2%

(40/1798)

4

Osteonecrosis

96%

(1722/1798)

5

Calcific tendinitis

1%

(24/1798)

Select Answer to see Preferred Response

PREFERRED RESPONSE 4

The atraumatic lesion shown in Figure A is most consistent with osteonecrosis (also known as avascular necrosis, or AVN). Initial MRI findings of AVN include decreased signal intensity in the subchondral region on both T1- and T2-weighted images, suggesting edema in early disease. In the shoulder, this is most commonly associated with the chronic use of corticosteroids, such as prednisone.

Sarris et al provide a review of osteonecrosis of the shoulder. They state that treatment is most effectively guided by staging of the disease, and that stage I and II disease can be treated conservatively. Surgical intervention is advocated when the patient is persistently symptomatic, and signs of articular collapse are evident. The surgical options include arthroscopic débridement, core decompression, vascularized bone grafting, and shoulder arthroplasty.

Incorrect Answers:
1-Gaucher disease is usually associated with large boney infarcts on MRI and severe pain. It is also a less common cause of AVN than chronic corticosteroid use.
2-Osteoarthritis is not frequently associated with subchondral collapse and fragmentation, especially in the absence of prior symptoms.
3-Chronic rotator cuff tendinopathy does not typically present with the changes noted on the MRI in Figure A.
5-Calcific tendinitis usually presents with severe acute pain, and a hypointense area within the soft tissues around the shoulder representing the calcific deposit. An example of calcific tendinitis is shown in Illustration A.

ILLUSTRATIONS:

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Question COMMENTS (2)

(OBQ10.10) A 37-year-old severe asthmatic has been taking daily corticosteroids for twenty years and now reports 4 months of worsening left shoulder pain. He is unable to complete a full day of work due to the pain. A radiograph is provided in Figure A. Which of the following describes the pathogenesis behind this disease process? Review Topic

QID:3098
FIGURES:
1

Cell-mediated immune response inciting synovial hypertrophy and mononuclear destruction of cartilage

2%

(33/1999)

2

Humoral immune response following a systemic infection in an HLA-B27 positive individual

0%

(7/1999)

3

Hyperuricemia induced crystalline deposition within the synovial fluid

0%

(3/1999)

4

Cellular death of the subchondral bone following an interruption in the vascular supply

97%

(1942/1999)

5

Bacterial seeding of the joint inducing polymorphonuclear cell destruction of the cartilage

0%

(4/1999)

Select Answer to see Preferred Response

PREFERRED RESPONSE 4

The radiograph demonstrates AVN of the humeral head and early collapse of the articular surface. Patients with radiographic evidence of proximal humerus AVN should also have hip radiographs performed as part of their evaluation.

Cruess reviews 95 patients with steroid-induced AVN of the humeral head reporting success with both conservative and arthroplasty treatment.

L'insalata et al reviews 65 shoulders with AVN of the humeral head reporting mixed results with 35 shoulders requiring arthroplasty after failure of conservative therapies. Surgical drilling and decompression did not alter the progression of disease.

Incorrect Answers:
Answers 1, 2, 3, and 5 describe rheumatoid arthritis, Reiter's Syndrome, gout, and septic arthritis respectively.


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Question COMMENTS (2)
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