Sample Size and Power Considerations for Surgical Trials

Determination of the number of subjects required for a randomized clinical trial (RCT) to achieve its primary objective is a critical component of study design. It reflects both scientific and ethical considerations since exposing patients to the risk of participating in a research study even if the risk is minimal is arguably unethical if the study is unlikely to answer its primary question. This chapter provides an overview of the most important elements, which orthopedic surgeons and researchers must consider with collaborating biostatisticians, to ensure that the sample size calculation is performed appropriately when designing RCTs. We begin with brief descriptions of confirmatory and exploratory studies, as these are the most common RCT types for testing surgical procedures and devices. The most important components of a sample size estimation in the context of these study types follows. We conclude with a summary, including practical recommendations and a select list of resources for further reading.