What are the procedures for core decompression in patients with avascular necrosis of the hip?

Core Decompression Procedures for Avascular Necrosis of the Hip

Core decompression is the recommended joint-preserving surgical procedure for early-stage avascular necrosis of the femoral head, with traditional single-tunnel and multiple small-diameter drilling techniques showing superior outcomes compared to non-operative management in pre-collapse stages. 1

Preoperative Assessment and Planning

• MRI is the preferred diagnostic method for avascular necrosis of the hip, especially when patients present with persistent hip pain but normal standard radiologic studies 2
• CT imaging provides valuable information for preoperative planning, showing the location and extent of articular collapse that may not be visible on radiographs 3
• 3D-printed guide plates can improve surgical precision, decrease operative time, and reduce blood loss during core decompression 3
• Preliminary hip arthroscopy may help identify patients with significant joint damage who might not benefit from the procedure 4

Core Decompression Techniques

Traditional Single-Tunnel Technique

• Uses a cannulated drill bit inserted into the lateral cortex of the proximal femur to reach the necrotic lesion 1
• Creates a single large tunnel through the femoral neck into the necrotic area 1
• Potential disadvantage: higher risk of subtrochanteric fracture due to larger cortical defect 1

Multiple Small-Diameter Drilling

• Involves creating multiple small drill holes rather than a single large tunnel 1
• Advantages: decreased risk of fracture through a less invasive technique 1
• Particularly beneficial for early-stage disease (Ficat stages I and II) 5
• Relatively simple procedure with less morbidity compared to more extensive techniques 5

Endoscopic/Arthroscopic-Assisted Core Decompression

• Preliminary hip arthroscopy helps identify patients with significant joint damage 4
• Tunnel endoscopy enables precise targeting of the lesion 4
• Allows thorough debridement of the necrotic area with accurate visual verification 4
• May lead to more accurate patient selection and more complete debridement 4

Augmentation Options

• Tantalum rods can be inserted to provide structural support 1
• Bone grafting (autologous or synthetic) may be used to fill the decompression tract 1, 6
• Fibular strut grafting shows better outcomes in more advanced disease (stage III) 5, 7
• Orthobiologics that may be added include:
  • Bone marrow aspirate concentrate 1
  • Mesenchymal stem cells 1
  • Platelet-rich plasma 1
  • Human umbilical cord mesenchymal stem cell extracts 1
• Electric stimulation has been studied as an adjunctive therapy 1

Postoperative Management

• Protected weight-bearing is recommended following core decompression procedures 3
• Regular follow-up with radiographic evaluation is essential to monitor disease progression 3
• NSAIDs and analgesics can provide symptomatic pain relief, although they do not alter disease progression 2

Procedure Selection Based on Disease Stage

• Stage I (pre-symptomatic with MRI changes only): Both single-tunnel and multiple small-diameter drilling show good outcomes 5, 7
• Stage II (pre-collapse):
  • Multiple small-diameter drilling is preferred due to simplicity and lower morbidity 5
  • Survival rates at 50 months: 65% for core decompression vs. 89% for vascularized fibular grafting 7
• Stage III (early collapse):
  • Core decompression with fibular strut grafting shows better clinical and radiological outcomes 5
  • Survival rates at 50 months: 21% for core decompression vs. 81% for vascularized fibular grafting 7

Potential Complications

• Subtrochanteric fracture is a risk, particularly with the traditional single-tunnel technique 6
• Augmentation with synthetic bone graft does not significantly improve mechanical properties but may reduce the risk of subtrochanteric fracture 6
• Iatrogenic avascular necrosis is the most serious potential complication of treatment 2