What are the treatment options for avascular necrosis (AVN)?

Treatment Options for Avascular Necrosis (AVN)

The management of avascular necrosis should be based on disease stage, location, and extent of involvement, with early-stage disease benefiting from conservative measures and core decompression, while advanced disease with articular collapse typically requires joint replacement surgery. 1

Diagnosis and Staging

• MRI is the gold standard for diagnosis, especially in early stages when X-rays appear normal

• Both sides should be imaged when evaluating hip pain, even if symptoms are unilateral

• The Ficat and Arlet classification is most commonly used for femoral head AVN:

  • Stage I: Normal radiographs, MRI changes only
  • Stage II: Sclerotic or cystic lesions without subchondral fracture
  • Stage III: Subchondral collapse/crescent sign
  • Stage IV: Secondary degenerative joint disease

• Necrotic volume assessment is critical:

  • ≥30% necrotic volume: 46-83% risk of collapse
  • <30% necrotic volume: <5% risk of collapse

Treatment Algorithm Based on Stage

Early-Stage Disease (Pre-collapse: Ficat I-II)

1. Conservative Management:

   • Protected weight-bearing with crutches or walker
   • Analgesics: Acetaminophen and NSAIDs (with caution in elderly or those with renal dysfunction)
   • Physical therapy once acute pain subsides
   • Address modifiable risk factors (corticosteroid use, alcohol consumption)
   • Consider bisphosphonates to improve bone density and prevent progression

2. Surgical Options for Early-Stage Disease:

   • Core decompression (first-line surgical intervention)
   • Augmentation techniques:
     • Autologous bone marrow cell implantation
     • Vascularized fibular grafting
     • Bone substitute filling
     • Electric stimulation

Advanced-Stage Disease (Post-collapse: Ficat III-IV)

1. Joint Preservation Attempts (limited success):

   • Osteotomies (for small, pre-collapse lesions in non-weight-bearing areas)
   • Vascularized bone grafting (role still not clearly defined)

2. Joint Replacement:

   • Total joint replacement (main treatment for advanced stages)
   • Resurfacing hemiarthroplasty (alternative for femoral or humeral head AVN)
   • For talar AVN: talar replacement, arthroplasty, or tibiotalar joint fusion

Site-Specific Management

Hip AVN (Most Common)

• Early stage: Core decompression with or without bone marrow aspirate
• Advanced stage: Total hip replacement (accounts for 10% of all hip replacements in the US)

Knee AVN

• Early stage: Protected weight-bearing, core decompression
• Advanced stage: Unicompartmental or total knee replacement

Shoulder AVN

• Early stage: Conservative management, core decompression
• Advanced stage: Humeral head resurfacing or total shoulder arthroplasty

Talus AVN

• Early stage: Protected weight-bearing, possibly with extracorporeal shock wave therapy 2
• Advanced stage: Hindfoot fusion or total talar replacement 3

Pain Management

• First-line: Regular acetaminophen and NSAIDs (with caution)
• Advanced pain control: Opioids for severe pain (used cautiously with reduced dosing in renal dysfunction)
• Avoid codeine due to side effects including constipation

Special Populations

• HIV-infected patients: Often ultimately require hip replacement; bisphosphonate therapy should be considered if bone densitometry demonstrates osteopenia 1
• Sickle cell disease patients: AVN is a common cause of severe chronic pain with limited treatment options
• Transplant patients: At high risk due to immunosuppressive therapy; may require surgical intervention

Emerging Therapies

• Mesenchymal stem cell therapy shows promise for improving functional prognosis, particularly in early stages 1
• 3D-printed total talar prostheses for talar AVN 3

Treatment Effectiveness

• Core decompression shows statistically higher success rates than conservative treatment for stage I hips only (84% vs 61%) 4
• Success rates for core decompression decrease significantly with advancing stages: 84% for stage I, 63% for stage II, and only 29% for stage III 4

The key to successful management is early diagnosis and intervention before articular collapse occurs, as joint-preserving procedures have much higher success rates in pre-collapse stages.