Venous thromboembolism is a serious complication after total hip replacement (THR) and total knee replacement (TKR). Previous studies have reported the incidence of both asymptomatic and symptomatic deep vein thrombosis (DVT) after TKR were higher in Taiwan than other countries in Asia. Therefore, the usage of prophylactic antithrombotics should be considered. The efficacy and safety of Xarelto (Rivaroxaban) for preventing venous thromboembolism has been proved. However, there is a lack of study using prospective design to evaluate the efficacy and safety of Xarelto after THR and TKR for Taiwanese. In this study, the investigators use a randomized controlled trial design comparing the incidence of DVT, pulmonary embolism, and complications between intervention and control groups.

This parallel study is conducted in a single hospital. The participants are divided into two groups. One group is provided with Xarelto, and the other one group is provided without any prophylactic antithrombotic. To check the presence of a deep vein thrombosis of the lower limb, bilateral sonographic examinations are arranged for all participants preoperatively and at 3 and 14 days postoperatively. One radiologists who was blinded to the nature of the study interpreted the results of the sonographic examination. The present of pulmonary embolism, DVT-related symptoms, and complications are recorded during the 3-months follow-up in orthopedics outpatients. The symptom which associated with DVT is defined as the signs of leg such as unusual pain, edema, swelling, warm skin, and red or discolored skin. Complications related to Xarelto include major bleeding, infection, and non-healing wound. The expected number of participants in each group is 89, which is calculated by G * Power version 3.1. The intention to treat analysis is used in this study. The investigators compare the incidences of DVT, pulmonary embolism, and complications between the two groups.

Inclusion Criteria:

• Undergo total knee replacement or total hip replacement

Exclusion Criteria:

• Recent antithrombotics use
• A history of a coagulopathy
• Recent thromboembolic disease
• Preoperative deep vein thrombosis screening presents positive
• Age below 20

All enrolled participants were included in the baseline analysis.

From the day of surgery until 3 months postoperatively.

Adverse events were assessed prospectively from the day of surgery until 3 months postoperatively. Deep vein thrombosis was detected by routine duplex ultrasonography on postoperative day 3 and day 14, and symptomatic venous thromboembolism was evaluated clinically during follow-up visits. Major bleeding events were defined as gastrointestinal or intracranial hemorrhage requiring medical intervention. All randomized participants were included in the adverse event analysis.