To investigate the influence of tourniquets on the earlypostoperative coagulation status in total knee arthroplasty (TKA) evaluated by thrombelastography (TEG).

From January 2019 to May 2020, 160 patients with knee osteoarthritis undergoing primary unilateral TKA in Department of Orthopaedics of the Affiliated Hospital of Xuzhou Medical University were randomly assigned to the tourniquet group and the non-tourniquet group with 80 patients in each group. The patients with serious medical comorbidities, history of thrombosis, positive ultrasound results for preoperative DVT, preoperative coagulant function abnormality, anticoagulant therapy contraindications and perioperative transfusion of blood coagulation factors or platelets were excluded. Lower extremity doppler ultrasonography was performed before operation and seven days after the operation, conventional coagulation tests and TEG were performed before operation, one day after operation and seven days after operation. The calculated blood loss, the occurrence of venous thrombosis, the parameters of conventional coagulation tests and TEG were compared between the two groups. The chi-square test was used to compared the transfusion rate and the incidence of thrombosis, etc. The conventional coagulation test and TEG variables, including fibrin degradation products (FDP), thrombin time(TT), reaction time (R), clotting time (K), α-angle (alpha), maximum amplitude (MA), coagulation index (CI), between the two groups were analyzed by t test, and repeated measurement analysis of variance was used for comparison at different time points.

The tourniquet group had significant higher blood loss [(1 036±238)ml vs. (852±220)ml, t=4.713, P<0.001], which were calculated by the Formula of Gross. There was no statistically significant difference in the transfusion rate and the incidence of thrombosis between the two groups (χ²=0.538, 0.132, both P>0.05). There was a significant difference in terms of FDP, D-dimer, R, MA and CI among the three time points in the tourniquet group, while in the non-tourniquet group, statistically significant differences were observed with regard to FDP, D-dimer, K, Alpha and CI(all P<0.05). At seven days after operation, the level of TT in the tourniquet group was lower than that of the non-tourniquet group(F=15.818, P<0.05), and the levels of FDP and D-dimer of the tourniquet group were higher than those of the non-tourniquet (F=18.795, U=1 314, both P<0.05). At seven days after operation, with regard to TEG, R value of the tourniquet group was significantly lower than that of the non-tourniquet group(F=4.438), whereas MA(F=87.088) and CI(F=5.282)in the tourniquet group was significantly higher than those in the non-tourniquet group (both P<0.05).

The use of a tourniquet during the whole TKA does not affect the transfusion rate and the incidence of thrombosis, but it may increase calculated total blood loss, and exacerbate the early postoperative blood hypercoagulability.