Practical research methods for orthopaedic surgeons.

Inherent to understanding an orthopaedic study is a fundamental knowledge of the study's design principles and statistics. Statistics, in part, allow a researcher to sample a portion of the population and use probability to decide whether the findings from the sample are likely to apply to the whole population. Although statistical jargon can be confusing, several simple principles guide the approach to research design. It is helpful for orthopaedic surgeons to review different study designs and their levels of evidence, to understand statistical jargon and the selection of the statistical test that is appropriate for given types of data, and to be familiar with the process of sample size calculations. Knowledge gained from statistical principles and research design is used to interpret study results. Such knowledge is invaluable for judging the value of new clinical evidence and for designing future studies.