Fig. 1　 Survivorship of shock wave and natural history groups

When the end point was total hip arthroplasty, survival at one year was 42.9% in the shock wave group and 45.1% in the natural history group; survival at two years was 35.1% in the shock wave group and 24.7% in the natural history group, without a significant difference( Kaplan- Meier and log rank test, p=0.749).