Table 1.

Preoperative stages of the 71 hips classified according to the Steinberg's classification system.

Stage	Characteristics	Number of Hips
0	Normal radiographs, bone scan, and MR images	0
I	Normal radiographs, abnormal bone scan, and MR images
A: mild	< 15% of head involvement	0
B: moderate	15% to 30%	2
C: severe	> 30%	1
II	Abnormal radiograph
A: mild	< 15% of head involvement	1
B: moderate	15% to 30%	3
C: severe	> 30%	24
III	Subchondral collapse producing a crescent sign
A: mild	< 15% of articular surface	0
B: moderate	Crescent beneath 15% to 30%	1
C: severe	Crescent beneath > 30%	2
IV
A: mild	< 15% of surface collapsed and depression is < 2 mm	2
B: moderate	15% to 30% collapsed or 2 to 4 mm depression	8
C: severe	> 30% collapsed or > 4 mm depression	24
V	Joint narrowing with or without acetabular involvement
A, B, or C	Average of femoral head involvement, as determined in Stage an d estimated acetabular involvement	3
VI	Advanced degenerative changes	0