What is the initial management for a patient with avascular necrosis (AVN) of the right femoral head without subchondral collapse?

Management of Avascular Necrosis of the Right Femoral Head Without Subchondral Collapse

For avascular necrosis (AVN) of the femoral head without subchondral collapse, core decompression is the recommended initial surgical intervention to prevent disease progression and preserve the native joint. 1, 2, 3

Assessment and Staging

• AVN is defined as bone death due to inadequate vascular supply, commonly affecting the femoral head in adults in their third to fifth decades of life 1
• The extent of necrosis is the most critical prognostic factor:
  • Lesions involving <30% of the femoral head have <5% risk of progression to collapse 1, 2, 4
  • Lesions involving >30% of the femoral head have 46-83% risk of progression to collapse 1, 2
• Additional risk factors for progression include:
  • Patient age >40 years 1, 2
  • Increased BMI (>24 kg/m²) 1, 2
  • Joint effusion 1, 2
  • Bone marrow edema surrounding the necrotic area 1, 2

Initial Management Approach

• Early diagnosis and intervention are crucial to prevent articular collapse and subsequent need for joint replacement 1, 2
• For AVN without subchondral collapse, treatment options include:

Non-surgical Options

• Protected weight-bearing to reduce stress on the femoral head 3, 4
• Pharmacological therapies (limited supporting evidence):
  • Statins 1, 2
  • Bisphosphonates 1, 2
  • Anticoagulants 1, 2
• Adjunctive therapies:
  • Extracorporeal shock wave therapy 1, 2
  • Hyperbaric oxygen 1, 2

Surgical Intervention

• Core decompression is the primary surgical option for early-stage disease without collapse 1, 2, 3
• The procedure can be enhanced with:
  • Injection of autologous bone marrow cells 1, 2
  • Vascular fibular grafting 1, 2
  • Electric stimulation 1, 2
• Arthroscopic approaches using multiple small-diameter tunnels can be considered, especially when concomitant intra-articular pathology exists 5

Post-Intervention Management

• Protected weight-bearing following core decompression to prevent fracture 3, 4
• Regular radiographic follow-up to monitor for disease progression or femoral head collapse 3, 4
• Monitoring for at least 3 years is recommended, as femoral head collapse >3 mm at 3 years from symptom onset is associated with progression to osteoarthritis 6

Important Considerations and Pitfalls

• AVN is often bilateral in nontraumatic cases (70-80%), requiring evaluation of both hips 1, 2
• Multifocal osteonecrosis can occur, potentially affecting the knee (44%), ankle (17%), and shoulder (15%) 1, 2
• If subchondral collapse occurs or core decompression fails, more definitive procedures like hemiarthroplasty or total hip arthroplasty may become necessary 1, 2, 3
• CT imaging is valuable for preoperative planning, showing the precise location and extent of the necrotic lesion 3, 4
• MRI is the most sensitive imaging modality for early diagnosis and staging of AVN 1, 7