What is the inpatient management of avascular (loss of blood supply to bone) necrosis?

Inpatient Management of Avascular Necrosis

The inpatient management of avascular necrosis (AVN) should focus on early diagnosis with MRI, aggressive pain control, and prompt surgical intervention when indicated, with total joint replacement being the main treatment for advanced stages of AVN. 1

Diagnostic Approach

• Imaging:

  • MRI is the gold standard for diagnosis, especially in early stages when X-rays appear normal 2, 1
  • Both sides should be imaged when evaluating hip pain, even if symptoms are unilateral 2
  • CT scans may be used when MRI is contraindicated

• Staging:

  • Ficat and Arlet classification is most commonly used for femoral head AVN 2
  • Necrotic volume assessment is critical: femoral heads with ≥30% necrotic volume have 46-83% risk of collapse versus <5% risk with <30% volume 2

Pain Management

1. First-line analgesics:

   • Regular acetaminophen (paracetamol) administration
   • NSAIDs with caution in elderly or those with renal dysfunction 1

2. Advanced pain control:

   • Opioids for severe pain with reduced dosing in renal dysfunction
   • Avoid codeine due to side effects including constipation 1

3. Adjunctive therapies:

   • Bisphosphonates may improve bone density and prevent progression
   • Calcium and vitamin D supplementation should accompany bisphosphonate therapy 1

Surgical Management

Early Stage AVN (Ficat I-II, pre-collapse)

• Core decompression:
  • First-line surgical intervention for early-stage disease 2, 3
  • Can be supplemented with:
    • Autologous bone marrow cells
    • Vascular fibular grafting
    • Electric stimulation 2
  • Core decompression with tensor fascia lata muscle pedicle bone graft shows 83% satisfactory outcomes in stage IIA, IIB, and early III 3

Advanced Stage AVN (Ficat III-IV, post-collapse)

• Total joint replacement (arthroplasty):

  • Main treatment for advanced stages with articular collapse 2, 1
  • For femoral head AVN with severe secondary osteoarthritis 2
  • Accounts for 10% of indications for total hip replacements in the US 2

• Alternative surgical options:

  • Resurfacing hemiarthroplasty for femoral or humeral head AVN with articular collapse 2
  • For talar AVN: talar resection/replacement with arthroplasty or tibiotalar joint fusion 2

Special Considerations

1. HIV-infected patients:

   • Routine radiographic monitoring in asymptomatic persons is not recommended 2
   • Most patients with symptomatic AVN will ultimately require hip replacement 2
   • Consider bisphosphonate therapy if bone densitometry demonstrates osteopenia 2

2. Multifocal AVN:

   • Common sites include hip (68%), knee (44%), ankle (17%), and shoulder (15%) 2
   • Screen for AVN at other sites when one site is affected, particularly in patients on steroids 2

3. Risk factor modification:

   • Address modifiable risk factors: corticosteroid use, hyperlipidemia, alcohol consumption 2, 4
   • Consider statin therapy for hypercholesterolemia, with caution regarding drug interactions in HIV patients 2

Rehabilitation

• Physical therapy and gentle mobilization once acute pain subsides 1
• Weight-bearing restrictions based on disease stage and surgical intervention
• Focus on restoring normal gait and function 1

Emerging Therapies

• Mesenchymal stem cell treatments show promise for improving functional prognosis, particularly in early stages 4
• Hyperbaric oxygen therapy may be considered as an adjunctive treatment 2

Pitfalls and Caveats

1. Delayed diagnosis:

   • AVN can be insidiously symptomatic in early stages 5
   • High index of suspicion needed in patients with risk factors
   • Normal X-rays do not rule out AVN; proceed to MRI when clinical suspicion exists

2. Surgical timing:

   • Delay in surgical intervention can lead to disease progression and poorer outcomes 1
   • If AVN threatens limb viability, immediate surgical intervention is necessary 1

3. Post-surgical monitoring:

   • Regular follow-up is essential to monitor for disease progression or complications
   • Evaluate contralateral joint even if asymptomatic

The management of AVN requires prompt diagnosis and intervention to prevent joint collapse and preserve function. While early-stage disease may benefit from joint-preserving procedures, advanced disease typically requires joint replacement for optimal outcomes.