This study aims to evaluate the efficacy of anti-factor Xa activity (aFXa) in predicting ecchymosis after total knee arthroplasty (TKA). One hundred and two unilateral primary TKA patients were recruited consecutively in this prospective observational study. Participants received rivaroxaban (10 mg p.o. qd) from postoperative day 1 (POD1) to POD35 and were divided into a non-ecchymosis group (group A) and an ecchymosis group (group B). AFXa was assessed as the primary outcome on POD1 and POD3. Prothrombin time (PT), activated partial thromboplastin time (APTT) and thromboelastography (TEG) were recorded both preoperatively and postoperatively (on POD1 and POD3). Other outcomes, including venous thromboembolism (VTE), blood loss and wound complications were also collected and compared. As a result, 27.5% of the participants (n = 28) were allocated into group B. Demographic data were comparable between the two groups. The aFXa levels in group B were significantly higher than those in group A on POD1 and POD3, and the aFXa level was assessed as an independent risk factor for ecchymosis. The cut-off value of aFXa was determined to be 121.38 ng/mL at maximal Youden index, associated with area under the receiver operating characteristics curve of 0.67. Group B experienced significantly more blood loss and wound complications than group A. No statistical difference was detected regarding PT, APTT and TEG parameters. AFXa is a promising parameter to predict ecchymosis after TKA. Patients with aFXa > 121.38 ng/mL should be considered as high-risk population for postoperative ecchymosis and may require intense monitoring or dosage modification of anticoagulants.

Bleeding patients exhibit different fibrinolytic phenotypes after injury, and the universal use of tranexamic acid (TXA) is doubted. We aimed to evaluate the efficacy of postoperative antifibrinolytic treatment in total hip arthroplasty (THA) patients with different fibrinolytic phenotypes. A retrospective analysis was conducted in 238 patients who underwent THA. Patients were divided into two groups by different fibrinolytic phenotypes (non-fibrinolytic shutdown and fibrinolytic shutdown), determined by the LY30 level on postoperative day 1 (POD1). The two groups were further stratified into four sub-groups based on different postoperative TXA regimens (Group A received no TXA postoperatively, while Group B did). Hidden blood loss (HBL), decline of hemoglobin (ΔHb), D-dimer (D-D), fibrinogen/fibrin degradation product (FDP), prothrombin time (PT), activated partial thromboplastin time (APTT), and demographics were collected and compared. The clinical baseline data were comparable between the studied groups. In patients who presented non-fibrinolytic shutdown postoperatively, Group B suffered significantly lower HBL and ΔHb than Group A on POD3 and POD5. In patients who presented postoperative fibrinolytic shutdown, Group B failed to benefit from the postoperative administration of TXA when compared to Group A. No difference was found in postoperative levels of D-D, FDP, PT, and APTT. Postoperative antifibrinolytic therapy is beneficial for THA patients who presented non-fibrinolytic shutdown postoperatively, while the efficacy and necessity should be considered with caution in those with fibrinolytic shutdown. LY30 is a promising parameter to distinguish different fibrinolytic phenotypes and guide TXA administration. However, further prospective studies are needed to confirm these findings.