Randomized controlled trials (RCTs) are the most rigorous clinical scientific investigations. This study methodology is the closest to a true experiment in which a group of patients with a specific condition are random- ly allocated to treatment groups and are then followed to determine outcomes. This type of design, when done well, is the least likely to include bias. It is powerful because if the patients are appropriately randomized, the two groups are comparable because all confounding vari- ables (known and unknown) are balanced between the two groups, and therefore the only difference between them is the intervention. Any difference in outcome can only be attributed to the treatment.
The difficulty with this study design is that it requires a significant amount of research time and it also is very expensive. As well, the results may not be generalizable to all patients who have the specific condition because patients who volunteer for this type of study are often systematically different from those who don’t volunteer.8,15,16 Patients who participate in RCTs5 are more educated, have better general health, and on average are more com- pliant with treatments.2 Therefore, the results of RCTs need to be interpreted in this light; however, the validity of the results of RCTs is greater than with any other study design.
Over the past decade, the number of RCTs has increased significantly in orthopedics in general and in subspecialty journals as well.4 It is important for the orthopedic surgeon to understand issues relating to the conduct and evaluation of this type of research. This arti- cle focuses on specific issues relating to RCTs and pro- vides examples relating specifically to knee surgery.