Potential Risk Factors Contributing To Development Of Venous Thromboembolism For Total Knee Replacements Patients Prophylaxed With Rivaroxaban: A Retrospective Case-Control Study

Rivaroxaban after total knee arthroplasty (TKA) is used to prevent postoperative venous thromboembolism (VTE); however, despite thromboprophylaxis, some patients still develop postoperative VTE. To determine whether tourniquet time, time to initiate rivaroxaban (TTIRIV), or Body Mass Index (BMI) was associated with postoperative VTE. A retrospective case-control study was conducted. Those patients that developed VTE despite prophylaxis (cases) were compared to controls (no VTE). A univariate analysis was conducted (p<0.05 statistically significant). Seven VTE cases were identified from 234 TKA-patients. Patients with and without VTE had BMI of 40.1 +/- 9.1 and 32.8 +/- 7.5, respectively (p = 0.064). TTI(RIV)in VTE and control group was 28.2 +/- 4.7 hours and 26.4 +/- 4.2 hours, respectively (p = 0.39). Mean tourniquet time in VTE and control group was 65.0 +/- 8.7 minutes and 49 +/- 8.8 minutes, respectively (p = 0.0007). Statistically significant differences in tourniquet times were noted between VTE and non-VTE group but not for TTI(RIV)and BMI. Prolonged tourniquet use could pose a potential risk factor for postoperative VTE. Thromboprophylaxis management may need to be adjusted, based on patient-specific factors that could include increasing doses of oral anticoagulants and/or mechanical prophylaxis. However, further large-scale studies are required to establish pathophysiology.