ARCO Stage 3C Corresponds to Ficat Stage III
ARCO stage 3C corresponds to Ficat stage III, representing femoral head osteonecrosis with subchondral fracture and early collapse.
Understanding Osteonecrosis Staging Systems
Osteonecrosis (also called avascular necrosis) is bone death due to inadequate vascular supply. Several staging systems have been developed for femoral head osteonecrosis, with the Ficat and ARCO systems being among the most commonly used 1.
Correlation Between ARCO and Ficat Staging Systems:
- ARCO stage 3C indicates subchondral fracture with significant collapse (>2mm) but preservation of the femoral head contour 2, 3
- This corresponds to Ficat stage III, which represents subchondral fracture with early collapse 4, 5
- Both staging systems at these levels indicate a critical transition point in disease progression where the femoral head structure begins to fail 6
Clinical Significance of This Staging Correlation
Understanding the correlation between staging systems has important clinical implications:
- Both ARCO 3C and Ficat III represent a critical threshold where joint-preserving procedures become less effective 4, 5
- At this stage, there is radiographic evidence of subchondral fracture with early collapse, which significantly impacts treatment decisions 2, 3
- CT imaging is essential at this stage to accurately assess the extent of collapse that may not be visible on plain radiographs 3
Diagnostic Features
On CT imaging, ARCO stage 3C/Ficat III typically shows:
On MRI, additional findings include:
Treatment Implications
The staging correlation between ARCO 3C and Ficat III has direct treatment implications:
- Joint-preserving procedures have limited success at this stage 6
- For patients under 50 years, procedures like free-vascularized fibular graft or trapdoor grafting may still be considered 6
- For older patients or those with extensive necrosis (>30% of femoral head), arthroplasty options become more appropriate 4, 6
Prognostic Considerations
- At ARCO 3C/Ficat III, the risk of progression to complete collapse is high 4
- Studies show that augmented core decompression at this stage has limited success, with survival rates (without arthroplasty) of approximately 76% at 2 years 4
- Lesions involving >30% of the femoral head volume have a significantly higher risk of failure [HR=3.291,95%CI (1.494-7.248)] 4
Understanding the correlation between ARCO stage 3C and Ficat stage III helps clinicians make appropriate treatment decisions and provide accurate prognostic information to patients with femoral head osteonecrosis.