Stage |
|
0 |
All diagnostic studies normal, diagnosis by histology only |
1 |
Plain radiographs and computed tomography normal, magnetic resonance imaging positive and biopsy positive, extent of involvement A, B, or C (less than 15 percent, 15 to 30 percent, and greater than 30 percent, respectively). |
2 |
Radiographs positive but no collapse, extent of involvement A, B, or C |
3 |
Early flattening of dome, crescent sign, computed tomography or tomograms may be needed, extent of involvement A, B, or C, further characterization by amount of depression (in millimeter) |
4 |
Flattening of femoral head with joint space narrowing, possible other signs of early osteoarthritis |