Background: The aim of this study is to provide an overview of randomized controlled trials (RCTs) in primary total knee arthroplasty summarizing the available high-quality evidence. Methods: Following PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, we searched the Cochrane Central Register of Controlled Trials (CENTRAL, 2019, Issue 3), Ovid MEDLINE, and Embase. We excluded nonrandomized trials, trials on unicompartmental knee arthroplasty or revision surgery, systematic reviews, and meta-analyses. Trials that met our inclusion criteria were assessed using a binary outcome measure of whether they reported statistically significant findings. These were then classified according to the intervention groups (surgical approach, tourniquet use, design, etc.). Results: Four hundred and three RCTs met the inclusion criteria and were included. The total number of patients in those 403 RCTs was 47,675. Only 33 RCTs (8.2%) reported significant differences between the intervention and the control groups. The trials were grouped into surgical approach 34, tourniquet 31, minimally invasive surgery 13, patient specific instrumentation 30, knee design 37, fixation 27, mobile bearing 47, navigation 50, polyethylene 19, technique 27, patella resurfacing 26, drain 19, closure 16, and others 27 RCTs. Conclusion: For the vast majority of patients, a standard conventional total knee arthroplasty with a surgical approach familiar to the surgeon using standard well-established components, with or without tourniquet, without surgical drain leads to satisfactory long-term clinical outcomes.