Fig. 1

The search results and selection procedure. The literature search identified 259 citations. Of these, 164 duplicates were removed. After examining the titles and abstracts of the 95 remaining articles, we excluded 77 papers according to the inclusion and exclusion criteria; the full text of 18 articles was retrieved. Fourteen articles were assessed for eligibility. In Palanne’s article, there were two subgroups comparing TXA + tourniquet group with TXA + NT group. So we divided the study into two groups. Finally, we identified 1720 TKAs (1690 patients) assessed in 15 randomized controlled trial