Table 1 Association Research Circulation Osseous classification of osteonecrosis [14, 15]
From: High-energy extracorporeal shock wave therapy for nontraumatic osteonecrosis of the femoral head
Stage | Findings | Subclassification | Quantitation |
|---|---|---|---|
0 | All present techniques normal | No | No |
I | Radiography and computed tomography normal; at least one of the other techniques is positive | Location of lesion Medial Central Lateral | Area of involvement (%) A: < 15% B: 15 to 30% C: > 30% Length of crescent A: < 15% B: 15% to 30% C: > 30% Surface collapse and dome depression A: < 15% and < 2 mm B: 15% to 30% and 2 mm to 4 mm C: > 30% and > 4 mm |
II | No crescent sign; Sclerosis, osteolysis, focal porosis | ||
III | Crescent sign and/or flattening of articular surface | ||
IV | Osteoarthritis, joint space narrowing, acetabular changes, joint destruction | No | No |