Fig.2.

Kaplan–Meier survival curves of precollapse cases. a) The cumulative five-year survival rates indicate that the collapse rate of precollapse osteonecrosis of the femoral head (ONFH) cases is 0% to 84.8%, in the order of smaller to larger lesion sizes. Type C2 progressed quickly, with 37% at one year and 58% at two years reaching the endpoint. b) Collapse rate of precollapse ONFH cases according to sex; there were no differences in terms of time to collapse (p = 0.453, log-rank test). c) Collapse rate of precollapse ONFH cases according to laterality; there were no differences in terms of time to collapse (p = 0.580, log-rank test). d) Collapse rate of precollapse ONFH cases according to steroid use; there were no differences in terms of time to collapse (p = 0.961, log-rank test).