Hip Core Decompression for Avascular Necrosis
Core decompression with bone grafting is the treatment of choice for young adults with early-stage (pre-collapse) avascular necrosis of the femoral head who have significant hip pain, particularly when the necrotic lesion involves less than 30% of the femoral head. 1, 2
Patient Selection and Staging
The success of core decompression depends critically on disease stage and lesion size:
- Optimal candidates: Pre-collapse disease (Ficat stages I-II or ARCO stages I-II) with lesions involving <30% of the femoral head, which have <5% progression to collapse 1, 2, 3
- Stage-specific outcomes: Success rates are 92.3% for Stage I disease, 54-100% for Stage IIA, but only 50% for Stage IIB when patients comply with postoperative restrictions 4
- Poor candidates: Late-stage disease with articular collapse (Ficat stage III-IV) should proceed directly to arthroplasty (hemiarthroplasty or total hip arthroplasty) rather than attempting joint preservation 2
Preoperative Assessment
CT imaging is essential for surgical planning to determine the precise location and extent of the necrotic lesion 1, 3. Standard AP pelvis and lateral femoral head-neck radiographs should be obtained, with MRI/MRA or CT when three-dimensional morphological assessment is needed 5.
Screen the contralateral hip, as 70-80% of nontraumatic avascular necrosis cases are bilateral 2.
Risk factors that worsen prognosis include age over 40 years, corticosteroid therapy, alcohol use, and preoperative Ficat stage III disease 2.
Surgical Technique
The procedure involves inserting a cannulated drill bit from the lateral cortex of the proximal femur into the center of the necrotic lesion to within 5mm of the articular surface 6, 7. Multiple small drilling techniques can decrease fracture risk through a less invasive approach 8.
Cancellous bone grafting should be performed by harvesting graft from the posterior iliac crest and placing it loosely into the central decompression channel 6, 7. 3D-printed guide plates can improve surgical precision and decrease operative time 1, 3.
Augmentation with Stem Cells
For early-stage avascular necrosis (pre-collapse), autologous bone marrow-derived stem cells combined with core decompression show significant clinical benefit in reducing femoral head collapse and delaying total hip arthroplasty 2. This represents a critical distinction from osteoarthritis, where the American College of Rheumatology explicitly recommends against stem cell injections due to lack of standardization 2.
Postoperative Management
Strict protected weight-bearing is mandatory following the procedure to prevent fracture 1, 2, 3. Non-compliance with weight-bearing restrictions dramatically reduces success rates—when excluding non-compliant patients, success rates improve from 67.85% to over 90% for early-stage disease 4.
Regular radiographic follow-up is essential to monitor for disease progression or femoral head collapse 1, 3.
Expected Outcomes
Core decompression with bone grafting demonstrates superior outcomes compared to nonoperative management:
- Radiographic progression: 46% of operatively managed hips showed no disease progression versus only 19% of nonoperatively managed hips 7
- Total hip replacement rates: 35% of operatively managed hips required THR versus 77% of nonoperatively managed hips 7
- Lesion size matters: Only 7% of hips with small lesions required THR after decompression and bone grafting, compared to 42-48% with intermediate or large lesions 6, 7
Complications
The complication rate is very low, with fractures occurring in less than 1% of cases (typically from falls during the first postoperative month) 6. Other rare complications include pulmonary embolism, pneumonia, and thrombophlebitis 7.
Critical Pitfall
Early detection and intervention are crucial—delay leads to articular collapse and eliminates joint-preserving options 2. Once collapse occurs (Stage III-IV), core decompression outcomes deteriorate significantly, with 49% requiring hip replacement for Stage IV disease 6.