What is the recommended treatment for avascular necrosis without subchondral collapse?

Treatment of Avascular Necrosis Without Subchondral Collapse

Core decompression is the primary surgical treatment recommended for avascular necrosis without subchondral collapse, as it can prevent disease progression and potentially avoid the need for joint replacement. 1

Staging and Assessment

Before initiating treatment, proper staging is essential:

• MRI is the gold standard for diagnosis and staging of avascular necrosis
• Assessment of necrotic volume is critical for prognosis:
  • Lesions with ≥30% necrotic volume have 46-83% risk of collapse
  • Lesions with <30% necrotic volume have <5% risk of collapse 1
• The Ficat and Arlet classification is most commonly used for femoral head AVN

Treatment Algorithm

Conservative Management

Conservative treatment alone is insufficient to stop disease progression but may be used as part of the overall treatment plan:

• Protected weight bearing (10 kg) for 6-12 weeks depending on lesion size 2
• Pain management with:
  • Regular paracetamol (acetaminophen)
  • NSAIDs (with caution in elderly or those with renal dysfunction)
  • Opioids for severe pain (used cautiously with reduced dosing in renal dysfunction) 1

Pharmacological Options

• Iloprost may be considered in ARCO stage I-II to reduce pain and bone marrow edema
• Alendronate (bisphosphonate) may improve bone density and prevent progression
  • Requires calcium and vitamin D supplementation
  • Note: These are off-label uses requiring appropriate patient education 3, 1
• Anticoagulants and statins are not recommended based on current evidence 3

Surgical Options

1. Core decompression (primary recommendation):

   • Most effective for early-stage AVN (Steinberg stages I-III)
   • Can be supplemented with:
     • Autologous bone marrow cell injection
     • Vascular fibular grafting
     • Electric stimulation 1, 2

2. Arthroscopically assisted therapy:

   • Success rate of 86% for patients with Steinberg stages I-III
   • For larger necrotic defects (Steinberg IIIc), limited weight bearing for 12 weeks post-procedure 2

3. Mosaicplasty (autologous osteochondral graft transplantation):

   • Indicated for patients <45 years with focal full-thickness lesions <3 cm²
   • Advantages: elimination of second procedure, superior mechanical properties, immediate weight bearing 4

4. Osteochondral allograft transplantation:

   • Appropriate for larger defects (>2.5 cm²) or with substantial loss of subchondral bone 4

Risk Factor Modification

Address modifiable risk factors:

• Reduce or discontinue corticosteroid use when possible
• Manage hyperlipidemia (consider statin therapy)
• Eliminate alcohol consumption
• Monitor the contralateral side, as bilateral involvement occurs in 70-80% of non-traumatic cases 1

Follow-up and Monitoring

• Regular radiographic monitoring to assess disease progression
• MRI follow-up to evaluate treatment response
• Physical therapy and gentle mobilization once acute pain subsides to restore normal gait and function 1

Prognosis

• Early intervention before subchondral collapse significantly improves outcomes
• If left untreated, AVN typically leads to subchondral fracture and collapse within 2 years 3
• For advanced stages with articular collapse, total joint replacement becomes the main treatment option 1

Emerging Therapies

Recent therapeutic advances based on mesenchymal stem cells show promise for improving functional prognosis, particularly in early stages of AVN 5.