The importance of statistics in documentation on hip prostheses

The authors illustrate the possibilities and the limits of instruments that statistics currently make available in the analysis of a medical series involving hip prosthesis surgery. An analysis of the survival rate constitutes one of the most important tools with regard to data in the study of the effectiveness of implants, but its correct application is influenced by the assumption that so-called censored cases have no differences in survival in relation to those that remain under observation even in periods that follow. Simulation reveals the need to process series with a high number of cases, in order to obtain reliable estimates. Finally, only multivaried techniques allow for a correct evaluation of the incidence that single factors have in causing failure of implants.