AVN MANAGEMENT
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Based on the textbook content retrieved, here is a comprehensive summary of Avascular Necrosis (AVN) / Osteonecrosis Management:
Avascular Necrosis (AVN) — Management
Definition
AVN (also called osteonecrosis, aseptic necrosis, or ischemic necrosis) is skeletal infarction resulting from disruption of blood supply to bone. It can be asymptomatic, cause self-limited discomfort, or lead to painful subarticular bone collapse and joint destruction.
— Goldman-Cecil Medicine
Causes / Risk Factors
| Category | Examples |
|---|---|
| Traumatic | Hip dislocation, femoral neck fracture |
| Corticosteroids | Long-term glucocorticoid therapy, Cushing disease |
| Vascular | Sickle cell disease, fat emboli, caisson disease (dysbaric) |
| Metabolic | Ethanol abuse, diabetes mellitus, hyperuricemia, hyperlipidemia |
| Other | HIV/AIDS, renal dialysis, organ transplantation, irradiation, Gaucher disease, pancreatitis, pregnancy |
The femoral head is the most commonly affected site at all ages. Non-traumatic AVN also affects the humeral head, femoral condyles, distal tibia, and talus.
Diagnosis
| Modality | Role |
|---|---|
| MRI | Most sensitive; detects bone marrow edema in early disease — modality of choice |
| Bone scintigraphy | Can detect AVN before plain radiographs; SPECT more accurate for femoral head vascularity |
| Plain radiographs | Late finding: patchy osteopenia + osteosclerosis reflecting skeletal repair |
| Crescent sign | Linear subchondral radiolucency = subarticular bone collapse (late, ominous sign) |
MRI demonstrating bone marrow edema is especially sensitive for detecting early osteonecrosis. — Goldman-Cecil Medicine
Staging (Ficat & Arlet / ARCO System)
| Stage | Features |
|---|---|
| I | Normal X-ray; MRI positive (marrow edema) |
| II | Sclerosis/cystic change; no collapse; X-ray changes present |
| III | Crescent sign — subchondral collapse; articular surface intact |
| IV | Collapse of articular surface; secondary osteoarthritis |
Management
Non-Operative (Conservative)
- Protected weight-bearing — reduces mechanical stress on the affected joint
- Analgesics / NSAIDs for pain control
- SONK (spontaneous osteonecrosis of the knee): typically self-limiting — managed with limited weight bearing until resolution
- Treat underlying cause (e.g., reduce corticosteroid dose if possible, manage sickle cell disease, alcohol cessation)
- Adjuncts: bisphosphonates, statins, anticoagulants (limited evidence)
Operative — Joint-Preserving (Pre-Collapse, Stages I–III)
| Procedure | Indication / Notes |
|---|---|
| Core decompression | Gold standard for early stages (I–II); reduces intraosseous pressure, promotes revascularization; can be combined with bone grafting |
| Core decompression + bone grafting | Structural support + biological stimulus; cancellous, cortical, or vascularized graft |
| Vascularized fibular graft | Provides structural support and blood supply; best for larger lesions in young patients |
| Osteotomy (rotational/flexion) | Rotates necrotic segment away from weight-bearing zone; used in selected cases in young patients |
Operative — Joint Replacement (Post-Collapse, Stage III–IV)
| Procedure | Indication |
|---|---|
| Total Hip Arthroplasty (THA) | Most common definitive treatment for advanced femoral head AVN with collapse |
| Hemiarthroplasty | May be used in elderly patients with femoral neck fractures leading to AVN |
| Total Knee Arthroplasty (TKA) | For advanced osteonecrosis of the knee with articular destruction |
| Anatomic TSA / Reverse TSA | For advanced humeral head osteonecrosis depending on rotator cuff integrity |
In undisplaced intracapsular femoral neck fractures, operative management is favored due to higher prevalence of nonunion, avascular necrosis, and fracture displacement in nonoperatively treated cases. — Rockwood & Green's Fractures in Adults
Humeral Head AVN (Special Consideration)
- Traumatic causes: 3-part fractures → 15–35% incidence; 4-part fractures → ~90% incidence of osteonecrosis
- Non-traumatic causes: steroids, alcohol, metabolic disorders, hemoglobinopathies, HIV
- Staging similar to femoral head AVN
- Treatment: conservative for early stages; anatomic TSA if rotator cuff intact; reverse TSA if rotator cuff deficient — Miller's Review of Orthopaedics
Key Principles Summary
- Early diagnosis (MRI) is critical — joint-preserving surgery is only possible before collapse
- Stage I–II → core decompression ± grafting (joint preservation)
- Stage III → consider vascularized graft vs. osteotomy vs. arthroplasty based on patient age and lesion size
- Stage IV → arthroplasty (THA/TKA/TSA as appropriate)
- Address the cause — stop steroids/alcohol when possible, treat underlying hematologic conditions
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