Fig. 2　 Survivorship of type C1 and type C2 hips by JMHLW classification

When the end point was total hip arthroplasty, survival at one year was 100% in type C1 and 33.8% in type C2; survival at two years was 88.9% in type C1 and 18.0% in type C2, with a significant difference( Kaplan-Meier and log rank test, p=0.001).