Avascular Necrosis of the Shoulder 733.41

 
ICD-9 Classification / Treatment
Etiology / Epidemiology / Natural History Associated Injuries / Differential Diagnosis
Anatomy Complications
Clinical Evaluation Follow-up Care
Xray / Diagnositc Tests Review References

Shoulder AVN ICD-9:

  • 733.41(shoulder), 733.40(unspecified), 733.49(other)

Shoulder AVN Etiology / Epidemiology / Natural History

  • Most commonly adults 20-50yrs old
  • Etiology: EtOH or prolonged high dose steriods.  Other risk factors: sickle cell, dysbarism, Gaucher's disease, trauma, high-dose radiation, thrombophilia, protein S & C defiencies, hypofibrinolysis.
  • Thought to be due to altered circulating lipids and coagulation mechanisms.
  • Marrow death occurs 6-12 hrs after ischemia, radiographic changes appear after 3 months, articular collapse within 6-12 months in 80% of patients with clinical AVN.

Shoulder AVN Anatomy

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Shoulder AVN Clinical Evaluation

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Shoulder AVN Xray / Diagnositc Tests

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  • MRI: If suspected but not seen or if only in one shoulder MRI is indicated.  MRI sensitivity and specificiaty=95% for early AVN. Not good for estimating the extent of lesion.
  • CT is the best technique to determine area of bone death.
  • Bone scans are sensitive but have large number of false positives and have no advantage over MRI
  • Evaluation should include lipid levels and possible screening for decreased levels of protein C and S and antithrombin III and increased levles of plasminogen activatoter inhibitor-1.

Shoulder AVN Classification / Treatment

Cruess RL, CORR 1978;86-93

ARCO Staging (Association for Research on Osseous Circulation) ARCO News 1992;4:41

  • Stage 0-Bone biopsy demonstrates AVN. All other tests normal. Generally treated non-operatively
  • Stage I-Bone scan or MRI positive. Lesions subdivided based on location (medial, central and lateral) and percentage of head involvement. Ia=<15% involvement; Ib=15-30%; Ic=>30%.  Treatment: consider core decompression in young patients or Alendronate 70mg weekly (Lai KA, JBJS 2005;87A:2155).
  • Stage II-Xray=osteoclerosis, cystic , osteopenia or mottled femoral head without collapse or acetabular involvement. Bone Scan/MF+RI=lesions subdivived based on location (medial, central and lateral) and percentage of head involvement. IIa=<15% involvement; IIb=15-30%; IIc=>30%.  Treatment: core decompression for IIa sclerotic disease in young patients.
  • Stage III-Xray=crescent sign; lesions subdivided based on location (medial, central and lateral) and percentage of head involvement. IIIa=<15% involvement or <2mm depression of head; IIIb=15-30% or 2-4mm depression; IIIc=>30% or >4mm depression.  Treatment:  Osteotomy vs vascularized fibula vs resurfacing vs THA.
  • Stage IV-Xray=flattened particular surface, joint space narrowing, acetabular changes, osteophytes.  Treatment: arthrodesis vs THA
  • Ficat based on plain radiographs. Stage I=symptomatic hip,no xray change. Stage II, xray= patchy areas that are radiolucent and radiodense. Stage III=“crescent sign”=subchondral collapse. Stage IV=articular surface collapse.
  • U of Pennslvania system (Steinberg). 0-normal MRI, XRAY, bone scan.1-abnormal MRI\bone scan .2-sclerotic\cystic changes on xray. 3-crescent sign. 4-flattened femoral head. 5-joint narrowing. 6-advanced DJD

Shoulder AVN Treatment Options

  • Avoid chronic steriod use, correct lipid and coagulation abnormalities.
  • conservative tx/ resticted activity usually ineffective. 
  • Electrical stimulation -some studies have shown benefit from pulsing electromagnetic fields applied externally for hip AVN.  further study needed
  • Alendronate 70mg weekly (hip AVN) (Lai KA, JBJS 2005;87A:2155).
  • Core Decompression (Dines JS, Arthroscopy 2007;23:103e1), (Laporte DM, CORR 1998:254:60
  • Surface Replacement (Copeland S, JBJS 2006;88:900)
  • Hemiarthroplasty
  • TSA
  • 5 10 16
  • Hemiarthroplasty vs TSA: no difference in outcome or ROM between hemiarthroplasty and TSA. Complication rate is significantly higher with TSA
    (22%) than with hemiarthroplasty (8%). TSA should be reserve for stage V osteonecrosis. (Feeley BT, JSES 2008;17:689).

Shoulder AVN Associated Injuries / Differential Diagnosis

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Shoulder AVN Complications

  • Humeral head collapse
  • Arthritis
  • Pain

Shoulder AVN Follow-up Care

  • Dependent on stage and treatment.

Shoulder AVN Review References

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