ARCO 3B Corresponds to Ficat Stage III
ARCO stage 3B corresponds to Ficat stage III, representing femoral head osteonecrosis with subchondral fracture and early collapse. 1
Understanding ARCO and Ficat Staging Systems
- ARCO (Association Research Circulation Osseous) and Ficat are two commonly used staging systems for osteonecrosis of the femoral head 1
- Both systems help guide treatment decisions based on disease progression 2
- The key feature distinguishing ARCO 3B is the presence of subchondral fracture with early collapse of the femoral head 1, 3
Radiographic and Imaging Features of ARCO 3B/Ficat III
- Subchondral fracture with early collapse is visible on imaging 1
- CT is superior to MRI for showing the location and extent of articular collapse 2
- Preoperative CT has revealed that 21% of femoral heads staged as ARCO stage I or II on radiographs were actually stage III on CT 2, 4
- ARCO 3B shows more frequent bone resorption area (72.0%), cystic change (52.0%), bone marrow edema (93.5%), and joint effusion (76.0%) compared to earlier stages 5
Clinical Implications of ARCO 3B/Ficat III
- Patients with ARCO Stage III hips typically do not benefit from head-preserving procedures 3
- For late-stage femoral head osteonecrosis with articular collapse, resurfacing hemiarthroplasty or total joint arthroplasty is often necessary 2
- Total hip arthroplasty generally provides better outcomes than bipolar prosthesis in cases of osteonecrosis of the femoral head at this stage 3
- Subchondral fracture lines in ARCO stage III occur most frequently in the anterolateral femoral head, suggesting this may be the initial location of collapse 6
Diagnostic Considerations
- MRI without IV contrast is usually appropriate for evaluating osteonecrosis following normal or suspicious radiographs 2
- CT without IV contrast is particularly valuable for preoperative planning and showing the extent of articular collapse 2
- Combined assessment of bone resorption area and cystic change has the best predictive value for identifying ARCO stage 3A progression to 3B 5
Treatment Planning
- The degree of collapse of the femoral head is significantly related to the degeneration of the acetabular cartilage 3
- For ARCO 3B/Ficat III, total hip arthroplasty is often the preferred treatment due to the presence of significant collapse 2, 3
- 3D-printed guide plates can improve surgical precision and decrease surgery time in cases where intervention is still considered 2