The Blood Saving Effect of Tranexamic Acid in Total Knee Arthroplasty With Rivaroxaban as Thromboprophylaxis

The aim of this study was to conduct a prospective, randomized, double-blind study and assess the efficacy of and safety for thromboprophylaxis of rivaroxaban in total knee arthroplasty patients when tranexamic acid is used for bleeding prophylaxis.

Total knee arthroplasty is an effective procedure for end-stage arthritis of the knee in terms of pain relief and functional recovery. However, this procedure is associated with a substantial perioperative blood loss. As high as 69% allogeneic blood transfusion rate was reported in patients receiving total knee arthroplasty when preoperative haemoglabin level was \<13 g/dl. Tranexamic acid (TXA), an antifibrinolytic, given intraoperatively, has been reported to be effective in reducing one third of postoperative blood loss in standard total knee arthroplasty. Our previous study showed that TXA reduced total blood loss from 1453mL to 833mL (p\<0.001) and the need for transfusion from 20% to 4% (p=0.014) in total knee patients with enoxaparin (Clexane; Glaxo-Smith-Kline, Brentford, United Kindom) for thromboprophylaxis.

In recent years, there have been more effective and practical methods for thrombophylaxis in total hip and knee replacement surgeries. Rivaroxaban is one of the first oral factor Xa inhibitors licensed for this regard. The advantages of rivaroxaban include oral administration, no need to monitor blood levels and no dosing adjustments which are convenient for short hospital stay in contemporary total knee arthroplasty. Its efficacy in preventing venous thromboembolism (VTE) after total knee arthroplasty have been extensitvely investigated in RECORD (Regulation of Coagulation in Orthopaedic surgery to prevent Deep-vein thrombosis and pulmonary embolism) 3 and 4 studies, and the results showed that rivaroxaban 10mg once daily was superior to enoxaparin 40mg subcutaneously once daily or 30mg every 12 hours for 10 to 14 days. Despite of its clinical efficacy in VTE prophylaxis, orthopaedic surgeons are still sceptic in routine use of rivaroxaban in knee and hip surgery and concerned about the increased risk of bleeding complications. A higher reoperation rate regarding wound complications within 30 days of hip and knee replacement in the rivaroxaban group than the tinzaparin group (2.94% versus 1.8%) was reported recently. Similar event has been reported in other studies. However, all these studies did not use TXA as bleeding prophylaxis after hip and knee replacement surgery. The risk of increasing VTE by use of TXA, owing to its antifibrinolytic effects, is the cause of concern.

The aim of this study was to conduct a prospective, randomized, double-blind study and assess the efficacy of and safety for thromboprophylaxis of rivaroxaban in total knee arthroplasty patients when TXA is used for bleeding prophylaxis.

Eligibility Criteria:
Inclusion Criteria:

* End-stage arthritis of the knee
* Failure of medical treatment or rehabilitation
* Hemoglobin \> 10g/dl
* No use of non-steroid anti-inflammatory agent one week before operation

Exclusion Criteria:

* Preoperative Hemoglobin ≦10 g/dl
* History of infection or intraarticular fracture of the affective knee
* Renal function deficiency (GFR \< 55 ml/min/1.73m2)which is relative contraindicated for venography
* Elevated liver enzyme, history of liver cirrhosis, impaired liver function and coagulopathy (including long-term use anticoagulant)
* History of deep vein thrombosis, ischemic heart disease or stroke