Management of Bilateral Avascular Necrosis (AVN) of the Femoral Head

Overview

Aetiology

Diagnosis and Imaging

• Early: normal or subtle sclerosis/cysts in the femoral head
• The crescent sign (best seen on frog-leg lateral) is pathognomonic - a subchondral fracture overlying the necrotic segment
• Late: femoral head collapse, joint space narrowing, acetabular changes

Classification

Ficat and Arlet Classification (most widely used)

ARCO Classification (additional details)

• A: <15% involvement
• B: 15-30% involvement
• C: >30% involvement

Management Algorithm

1. Has the femoral head collapsed?
2. What is the extent of necrosis (lesion size)?

BILATERAL AVN
    │
    ├── PRE-COLLAPSE (Ficat I-II / ARCO I-IIC)
    │       │
    │       ├── Small lesion (<30% head), young patient, non-steroid
    │       │       → Core decompression ± bone marrow concentrate
    │       │
    │       ├── Moderate/large lesion, age <50 years
    │       │       → Free vascularised fibular graft (FVFG)
    │       │
    │       └── Symptomatic, asymptomatic or high risk of collapse
    │               → Bisphosphonates, protected weight bearing, 
    │                  +/- extracorporeal shockwave therapy
    │
    └── POST-COLLAPSE (Ficat III-IV / ARCO III-IV)
            │
            ├── Small/moderate lesion, age <55, idiopathic/post-traumatic
            │       → Proximal femoral osteotomy (selected cases)
            │
            └── Large lesion, >30% head, older patient, or degenerative changes
                    → Total Hip Arthroplasty (THA) - procedure of choice

Non-operative (Conservative) Management

• Protected weight bearing - reduces loading, may slow collapse; crutches/walker as needed
• Bisphosphonates (e.g., alendronate 70 mg/week) - inhibit osteoclast-mediated bone resorption; some evidence for slowing collapse in early stages, but not well established for reversing disease
• Lipid-lowering therapy (statins) - particularly relevant in steroid-induced AVN; some evidence for risk reduction in renal transplant patients
• Anticoagulants - considered in thrombophilia-related AVN
• Extracorporeal shockwave therapy (ESWT) - may stimulate vascularisation in early stages; results are promising but evidence limited
• NSAIDs / analgesia - symptom control only
• Address the cause - reduce/stop steroids if possible, treat underlying haemoglobinopathy, treat hyperlipidaemia

Natural history: >85% rate of femoral head collapse at 2 years in symptomatic Ficat stage I or II disease. Asymptomatic lesions <30% of head tend to remain stable (95% over 5 years), but lesions >50% will almost invariably progress.

Operative Management - Pre-Collapse Stage

1. Core Decompression

• Ficat stage I and IIA, small central lesions in young, non-obese patients not taking steroids
• Results much less predictable in stage III - explore alternatives

• Traditional (trephine): 8-10 mm core tunnel drilled from lateral cortex through femoral neck into necrotic zone; cortical window created
• Percutaneous multiple drilling (Mont technique): Multiple passes with 3.2 mm Steinmann pin under fluoroscopic guidance; lower morbidity, lower femoral head collapse rate than traditional technique
  • Postop: 50% weight bearing for 5-6 weeks, no high-impact activity for 12 months

• Patients should be advised that there is a 30% likelihood of requiring THA within 4-5 years even after early-stage core decompression
• Core decompression does not substantially alter the surgical field for subsequent THA if needed

2. Core Decompression + Bone Grafting

• Structural bone graft (cortical or cancellous) placed via the core track to support subchondral bone
• No significant difference in results between tibial/fibular autograft and fibular allograft for stage I-II disease
• Approaches: standard core track ("trapdoor"), "light bulb" technique
• Success rates of 50-80% reported

3. Free Vascularised Fibular Graft (FVFG)

1. Decompresses the femoral head
2. Excises the sequestrum
3. Fills defect with osteoinductive cancellous graft + viable cortical strut to support subchondral bone
4. Protected weight bearing promotes healing

4. Biological / Regenerative Adjuncts

• Bone marrow aspirate concentrate (BMAC) / Mesenchymal stem cell therapy combined with core decompression: A 2025 meta-analysis (Bharti et al., PMID 40651741) showed significant benefit in delaying or preventing collapse vs. core decompression alone
• Orthobiologics (PRP, stem cells) with core decompression: A 2025 systematic review (Zaffagnini et al., PMID 39543728) found these therapies delay the need for hip arthroplasty
• Network meta-analysis (Wang et al., 2024, PMID 38273397): Regenerative therapies outperform core decompression alone for preventing femoral head necrosis progression

Operative Management - Post-Collapse Stage

5. Proximal Femoral Osteotomy

• Transtrochanteric rotational osteotomy (anterior rotation / posterior rotation)
• Varus/valgus intertrochanteric osteotomy

• Age <55 years
• Small-to-medium lesion (<30% femoral head involvement)
• Idiopathic or post-traumatic (not steroid- or alcohol-induced, which have worse results)
• Post-collapse (Ficat III) where articular cartilage is relatively preserved

6. Total Hip Arthroplasty (THA)

• Lesion involves >30% of the femoral head
• Ficat stage III with collapse, or stage IV (established osteoarthritis)
• Failed conservative or joint-preserving surgery
• Age >50 years with symptomatic disease
• Bilateral disease with major functional impairment

• Hemiarthroplasty is generally avoided - acetabular cartilage is routinely damaged in Ficat III disease, and long-term results favour THA over hemiarthroplasty
• Sequential bilateral THA is usually performed; simultaneous bilateral THA may be considered in carefully selected patients (fit patients, significant bilateral disability) but carries higher perioperative risk
• Resurfacing arthroplasty is an alternative in selected young patients with Ficat III-IV disease and good acetabular bone stock; results for osteonecrosis are comparable to other aetiologies at 2-12 years
• THA in AVN patients tends to be technically more demanding due to younger age, potential bone stock issues, and risk of dislocation

Special Considerations in Bilateral Disease

Summary Table: Treatment by Stage

Recent Evidence Update (2024-2025)

• A 2024 systematic review (Goncharov et al., PMID 39051378) confirmed conservative treatment alone is insufficient for most patients and emphasizes risk factor modification alongside procedural intervention
• Stem cell therapy combined with core decompression is the most promising joint-preserving advance, particularly for pre-collapse bilateral disease in young patients
• Regenerative strategies (BMAC, PRP, MSC) appear to delay THA conversion by several years in Ficat I-II disease