Core Decompression Technique for Early-Stage Femoral Head AVN
For a patient with early-stage bilateral femoral head AVN (intact articular surface, <30% necrotic volume), core decompression should be performed using a percutaneous drilling approach with fluoroscopic guidance, followed by biological augmentation with bone marrow aspirate concentrate (BMAC) or autologous bone grafting to optimize outcomes. 1, 2
Patient Positioning and Setup
Position the patient supine on a hip arthroscopy table with a perineal post. Apply traction to the operative limb, which allows concurrent treatment of any intracapsular pathology before proceeding with core decompression 1. This setup provides optimal fluoroscopic visualization and surgical access.
Surgical Approach
Incision and Access
Make a lateral incision over the proximal femur at the level of the greater trochanter 1. This lateral trochanteric approach provides direct access to the femoral head while minimizing soft tissue disruption 3.
Guidewire Placement
Under continuous fluoroscopic guidance in both AP and lateral views, introduce a guidewire into the necrotic region of the femoral head. The entry point should be at the lateral cortex of the proximal femur, with the trajectory aimed toward the center of the necrotic lesion beneath the subchondral surface 1.
Core Decompression Execution
Drilling Technique
Use percutaneous drilling with multiple small-diameter trephines (rather than a single large 8-10mm trephine) to minimize fracture risk 2. The large-diameter trephine carries significant fracture risk and may not allow healing across large gaps 2.
Drill from the lateral cortex to just beneath the subchondral surface, stopping approximately 3-5mm from the articular cartilage to prevent breakthrough 1.
Necrotic Tissue Removal
Use an expandable reamer to remove necrotic bone tissue from within the femoral head 1, 4. Follow with curettes to thoroughly debride all necrotic material, creating a cavity for biological augmentation 1.
Biological Augmentation
The addition of biological support significantly improves outcomes compared to core decompression alone, particularly in stages 2B and 2C 4, 5.
Preferred Options (in order):
Autologous bone from femoral neck: Impaction of autologous cancellous bone harvested from the femoral neck or iliac crest into the necrotic defect shows superior results, with 100% success in stage 2A and 84.6% in stage 2B lesions 4, 3
Bone marrow aspirate concentrate (BMAC): Inject BMAC through the decompression tract into the femoral head 2, 5. This can be combined with stromal vascular fraction for enhanced biological support 5
Calcium phosphate bone graft substitute: If autologous bone is unavailable, inject calcium phosphate composite into the femoral head and allow to cure 1
Critical Technical Points
Fluoroscopic Verification
Confirm guidewire and reamer position in both AP and lateral planes throughout the procedure to ensure accurate targeting of the necrotic zone and avoid subchondral penetration.
Decompression Adequacy
The aspirate needle itself can serve as an initial decompression tool before introducing larger instruments 2. Ensure complete removal of necrotic tissue, as incomplete debridement compromises outcomes.
Bilateral Cases
For bilateral disease (present in 70-80% of non-traumatic cases 6), stage procedures 6-8 weeks apart to allow initial recovery and minimize anesthetic burden.
Common Pitfalls to Avoid
- Subchondral breakthrough: Stopping 3-5mm short of the articular surface prevents catastrophic cartilage damage
- Using large single trephines: The 8-10mm trephine increases fracture risk; multiple small-diameter percutaneous drilling is safer 2
- Inadequate necrotic tissue removal: Incomplete debridement leads to persistent disease progression
- Omitting biological augmentation: Core decompression alone has inferior outcomes compared to augmented techniques 4
Expected Outcomes
With this technique, radiographic survival rates exceed 76.9% at 2-year follow-up, with total hip arthroplasty survival rates above 72.1% 1. Success rates approach 100% for stage 2A lesions and 84.6% for stage 2B when autologous bone is used 4. Patient-reported outcomes show significant improvement, with Harris Hip Scores increasing from mean 69.45 preoperatively to 83.55 at 6 months 3.
Important caveat: The overall efficacy of core decompression at preventing eventual articular collapse remains controversial in the literature 6, though outcomes are clearly superior in early-stage disease (<30% necrotic volume) where progression to collapse occurs in <5% of cases 6.