Principles of Designing an Orthopaedic Case-Control Study

Many surgical questions are not amenable to investigation with a randomized controlled trial; thus, investigators must select an appropriate observational study design. Case-control studies are relatively inexpensive and can be conducted in comparatively little time. Although there are important methodological limitations associated with this trial design, case-control studies can provide important insight into the association between one or more exposures and a specific outcome. They are particularly useful when the outcome of interest is rare or when the time to development of the outcome is long. We present an overview of the case-control study, with a focus on trial design and interpretation of results.