Abstract: OBJECTIVE: The use of tourniquets can reduce intraoperative blood loss during total knee arthroplasty, which can increase the stability of the prosthesis. The use of tourniquet includes the use of tourniquet in the whole process and the use of tourniquet in part of the operation. How to use tourniquet is still controversial. Meta-analysis was used to evaluate the efficacy and safety of tourniquet in total knee arthroplasty and only at the time of cementing.
METHODS: We searched randomized controlled trials involving different tourniquet use techniques during total knee arthroplasty and only when installing prosthesis through PubMed, the Cochrane Library, the Chinese National Knowledge Infrastructure Database, and the Wanfang database. Relevant data were extracted and analyzed using RevMan 5.3 software to evaluate the difference of related outcomes between the two groups. 
RESULTS: (1) A total of 624 patients from 11 randomized controlled trials were included. Among them, 322 patients used tourniquet during the whole procedure, and 302 patients used tourniquet only at the time of cementing. (2) The results of the meta-analysis showed that compared with the group using tourniquet only at the time of cementing, intraoperative blood loss and hospital for special surgery knee score were lower [MD=-175.38, 95%CI (-243.26, -107.50), P < 0.000 1; MD=-9.20, 95%CI(-17.82, -1.13), P=0.03]; postoperative drainage volume, hidden blood loss, visual analogue scale score of knee joint incision on the first day after operation, incidence of secondary complications and incidence of deep venous thrombosis of lower extremity were higher [MD=65.71, 95%CI(41.45, 89.97), P < 0.000 1; MD=141.44, 95%CI(63.46, 219.42), P=0.004; MD=0.35, 95%CI(0.06, 0.64), P=0.02; MD=2.53, 95%CI(1.42, 4.52), P=0.002; MD=2.68, 95%CI(1.22, 5.87), P=0.01] in the group that used a tourniquet during the entire surgical procedure. There was no significant difference in operation time, total blood loss, visual analogue scale score of knee joint incision at postoperative 2 and 3 days, and blood transfusion rate between the two groups (P > 0.05).
CONCLUSION: Compared with the use of tourniquet during the entire surgical procedure, tourniquet use only at the time of cementing can reduce the postoperative blood loss, drainage volume and hidden blood loss, as well as early postoperative knee incision pain, obtain better knee function, reduce the incidence of complications and the incidence of lower extremity deep vein thrombosis.

Key words: bone, joint arthroplasty, prosthesis, total knee arthroplasty, tourniquet, meta-analysis