Magnetic resonance imaging of avascular necrosis of the femoral head: predictive findings of total hip arthroplasty.

BACKGROUND: Avascular osteonecrosis of the femoral head (AVNFH) is an ischemic condition which despite different treatments often leads to collapse of the femoral head and to total hip arthroplasty. However, the magnetic resonance imaging findings predisposing to disease progression and total hip arthroplasty are somewhat elusive. PURPOSE: To evaluate the magnetic resonance imaging findings of AVNFH and to assess the patterns of findings which may predict total hip arthroplasty. MATERIALS AND METHODS: A retrospective study was conducted with a total of 18 diagnosed AVNFH treated with core decompression combined with intraosseous stem cell treatment. After treatment, magnetic resonance imaging follow-ups were done at three-month and one-year follow-up or until total hip arthroplasty. Association Research Circulation Osseous classification and magnetic resonance imaging findings such as the size and the location of the AVNFH, bone marrow edema in femoral neck, effusion and subchondral fracture were evaluated. RESULTS: Hips advancing to total hip arthroplasty have more often bone marrow edema in femoral neck (90% vs. 0%), adjacent to necrotic lesion (100% vs. 43%) and in acetabulum (90% vs. 14%), but also subchondral fractures (70% vs. 0%), effusion (80% vs. 29%), and synovitis (80% vs. 14,3%). The greater size and the lateral weight-bearing location of the necrotic lesion also predicted future total hip arthroplasty. CONCLUSION: Hips advancing to total hip arthroplasty have often a combination of pathognomonic AVNFH imaging findings compared to hips not advancing to total hip arthroplasty.

MRI-guidance in percutaneous core decompression of osteonecrosis of the femoral head.

OBJECTIVES: The purpose of this study was to evaluate the usefulness of MRI-guidance for core decompression of avascular necrosis of the femoral head. MATERIALS AND METHODS: Twelve MRI-guided core decompressions were performed on patients with different stages of avascular necrosis of the femoral head. The patients were asked to evaluate their pain and their ability to function before and after the procedure and imaging findings were reviewed respectively. RESULTS: Technical success in reaching the target was 100 % without complications. Mean duration of the procedure itself was 54 min. All patients with ARCO stage 1 osteonecrosis experienced clinical benefit and pathological MRI findings were seen to diminish. Patients with more advanced disease gained less, if any, benefit and total hip arthroplasty was eventually performed on four patients. CONCLUSIONS: MRI-guidance seems technically feasible, accurate and safe for core decompression of avascular necrosis of the femoral head. Patients with early stage osteonecrosis may benefit from the procedure. KEY POINTS: • MRI is a useful guidance method for minimally invasive musculoskeletal interventions. • Bone drilling seems beneficial at early stages of avascular necrosis. • MRI-guidance is safe and accurate for bone drilling.