Table 4.

The results of Cox proportional-hazards model for conversion to THA

Variable selected	B	SE	Wald	P value	95% CI
ARCO stage	1.991	0.835	5.689	0.017*	1.426–37.567
Bilateral disease	0.352	0.504	0.487	0.485	0.529–3.817
Bone marrow edema	3.531	1.279	7.627	0.006*	2.787–418.683
Osteonecrotic lesion ≥ 30%	1.873	1.100	2.902	0.088	0.754–56.173
Age > 40 years	3.023	1.494	4.096	0.043*	1.100–383.818
Harris hip score ≥ 80 points	− 13.182	404.806	0.001	0.974	0.000~
Gender	0.292	1.373	0.045	0.832	0.091–19.743
Corticosteroids intake	0.334	1.708	0.038	0.845	0.049–39.743

*Indicate the significant P value. B regression coefficient, SE standard error