Rates of venous thromboembolism in contemporary studies of primary total knee arthroplasty (TKA) have been reported to be as high as 3.5%. Although drug prophylaxis is effective, the best option among these regimens is not well established. The purpose of this study was to evaluate the comparative effectiveness and safety of aspirin, low-molecular-weight heparin, synthetic pentasaccharide factor Xa inhibitors, and vitamin K antagonist.
Data were from a US total joint replacement registry, with 30,499 patients receiving unilateral TKA from May 16, 2006, to December 31, 2013. Patients received either aspirin (324-325 mg daily), enoxaparin (40-60 mg daily), fondaparinux (2.5 mg daily), or warfarin (all doses) and were followed up 90 days postoperatively on several outcomes: deep vein thrombosis, pulmonary embolism, major bleeding, wound complications, infection, and death.
There was no evidence that fondaparinux, enoxaparin, or warfarin were superior to aspirin in the prevention of pulmonary embolism, deep vein thrombosis, or venous thromboembolism or that aspirin was safer than these alternatives. However, enoxaparin was found to be as safe as aspirin with respect to bleeding, and fondaparinux was as safe as aspirin for risk of wound complications.
Among TKA patients, we did not find evidence for decreased effectiveness or increased safety with use of aspirin, but enoxaparin had comparable safety to aspirin for bleeding and fondaparinux had comparable safety to aspirin for wound complications.