Our study is the first meta-analysis to identify relevant randomized controlled trials involving TXA plus a tourniquet and use of TXA plus no tourniquet during TKA. This meta-analysis of 15 RCTs that evaluated a total of 1720 TKAs shows that TXA plus tourniquet group can decrease intraoperative blood loss and surgery duration however increase hidden blood loss and decrease the knee ROM. Our findings suggested that there were no significant differences in terms of total blood loss, decrease in hemoglobin, transfusion rate, drainage volume, VAS, HSS, Knee circumference, Knee ROM, LOH, and complications between the two groups.
The result showing that the use of a tourniquet plus TXA effectively reduced intraoperative blood loss was consistent with the outcome of previous meta-analysis (35–37). However, we found the TXA-T group has more hidden blood loss. An explanation for these conflicting results of IBL and HBL indicates that hidden blood loss plays a key role. Tourniquet release can result in ongoing bleeding from cut cancellous bone (38), blood extravasated into the knee joint and adjacent soft tissues(39), or blood loss from hemolysis(40) because of tourniquet-induced ischemia(41, 42). Furthermore, there are no differences in drainage volume and total blood loss between the two groups, which is inconsistent with the previous meta-analysis. At an earlier meta-analysis(13, 37, 43), they found total blood loss to be significantly lower with a tourniquet. We think the reason for the difference between our study and previous meta- analysis(13, 37, 43) is the TXA used in all RCT studies included in our meta-analysis.
Hemoglobin level and transfusion rate have been recognized as the most objective indicators of actual blood loss. The decrease in hemoglobin and transfusion rate was similar in the TXA-NT group compared with the TXA-T group in our study. Blood transfusion is associated with adverse effects, including hemolytic reactions, infections, morbidity, immunologically mediated diseases, and cost (44). The result of similar transfusion rate in both groups is consistent with Cai’s recent meta-analysis(45). They found no significant difference between the tourniquet group and the non-tourniquet group.
A tourniquet will provide surgeons with a bloodless surgery field to facilitate the clear identification of anatomical structures with less electrocoagulation and wound irrigation during surgery, which might help shorten the operation time. Our result showed tourniquet with TXA use reduced surgery duration, which was consistent with previous studies (2, 35, 38). So a reduction of course of surgery is a potential benefit of tourniquet use with TXA in TKA.
Pain relief in the early postoperative period after TKA is crucial in facilitating early recovery. Whether the use of tourniquets will increase postoperative pain remains controversial. Theoretically, tourniquet use may increase thigh pain and swell due to lower limb blood flow occlusion and ischemia-reperfusion injury. Our study identified no difference in pain intensity at either the day of surgery, first day, second day, the third day, fifth day, the seventh day, or one month after surgery. Although tourniquet pressure, time, and time of postoperative pain evaluation were variable across studies, we found that these factors of all included RCTs were comparable between experimental and control groups, so endpoints like VAS, ROM, and LOS could still be properly assessed. We also have tried our best to evaluate VAS based on time points. Our results of VAS were inconsistent with previous studies.(25, 46, 47). It may be related to the tourniquet pressure in our tourniquet group. In our study, lower or personalized tourniquet pressure was used in 5 of the 11 RCTs. Worland et al. (48)showed an essential correlation between higher tourniquet pressure and more thigh pain in the immediate postoperative period.
Knee flexion ROM is often used to evaluate short-term effectiveness. Besides, discharge from the hospital is dependent on the mobility of patients following TKA. We found significantly decreased knee ROM in TXA-T group compared with TXA-NT group, which is inconsistent with the previous systematic review of 26 RCTs (13). We think the reason is that some studies in the previous analysis didn’t use TXA, and we included studies with TXA use, which may make the advantage of hemostasis effect with tourniquet less obvious compare with non-tourniquet group, So the impact on the knee range of motion appears more obvious compared with non-tourniquet group. No significant difference was also found in terms of knee circumference between the two groups. These findings seem logical, given that we found no significant difference in terms of VAS.
The analysis of the postoperative HSS at either seven days 、 one-month 、 three months or six months after the surgery also did not reveal a difference. HSS might be affected by many factors such as pain, ROM, function, muscle force, and flexion deformity. Moreover, the effect of a tourniquet application plus TXA on HSS needs to be further confirmed by more high-quality studies.
As for complications, we observed no significant difference in terms of IMVT, DVT, superficial infection, deep wound infection, delayed wound healing between the two groups. Although TXA use in TKA didn’t increase thromboembolic events(49–52), perhaps one of the more significant clinical concerns regarding tourniquet use plus TXA is its association with thromboembolism. No significant difference was found between groups regarding the rate of intramuscular venous thrombosis and deep venous thrombosis in our study. Several studies have investigated the incidence of venous thrombosis with the use of the tourniquet(3, 13, 14, 36, 53). However, the evidence is mixed because of heterogeneous study groups and designs, making it difficult to compare. Nonetheless, we cannot underscore the importance of chemoprophylaxis following TKA regardless of tourniquet use. DVT was detected in 81% of patients when all the patents only received mechanical compression but no chemoprophylaxis following TKA of tourniquet use(54).
The current meta-analysis has several limitations: First, there is a high heterogeneity of blood loss caused by the different methods for measuring blood loss, separate application of a tourniquet, different operative techniques, and different perioperative management as the drain and anticoagulant therapy. The reliability of results maybe influenced by this heterogeneity. Second, the studies' comparability was complicated through the different measurement methods and follow-up examination time points; however, we have tried our best to evaluate results based on time points. Third, the tourniquet time, the time for loosening the tourniquet, and the cuff pressure used were also not uniform. Fourth, there are no worldwide uniform guidelines for performing total knee arthroplasty. Different surgical techniques (such as the selection of approach, anesthesia methods, patellar resurfacing, and type of prosthesis) were used in the individual studies.