The Impact of Anticoagulant Choice on Rates of Manipulation Under Anesthesia, Hematoma Formation, and Venous Thromboembolic Events.

BACKGROUND: Anticoagulation after total knee arthroplasty (TKA) remains a balance between clot prevention and postoperative bleeding. This study aimed to analyze anticoagulant choice for deep vein thrombosis prophylaxis on rates of stiffness requiring manipulation under anesthesia (MUA) and hematoma formation after TKA.

METHODS: A large national database was queried for all primary TKAs. We included patients who filled a prescription for an anticoagulant within three days before or five days after surgery. We excluded those who filled prescriptions for multiple or no anticoagulants. Logistic regression was used to compare potent anticoagulants (warfarin, Xa inhibitors, and low molecular weight heparin (LMWH)) to our control group receiving aspirin. The primary outcomes of interest were MUA or hematoma formation within 90 days postoperatively. After applying the exclusion criteria, 462,869 patients were available to review. Of those, 148,159 (32.05%) received aspirin, followed by factor Xa inhibitors (123,909 [26.80%]), warfarin (96,338 [20.84%]), and LMWH (84,962 [18.38%]).

RESULTS: Using logistic regression analyses, patients receiving factor Xa inhibitors (odds ratio [OR] 1.38 [95% confidence interval (CI) 1.32 to 1.43]), indirect factor Xa inhibitors (OR 1.33, [95% CI 1.19 to 1.48]), warfarin (OR 1.29 [95% CI 1.23 to 1.35]), and LMWH (OR 1.26, [95% CI 1.20 to 1.32]) had higher rates of MUA than the aspirin cohort. Additionally, when compared to aspirin, those receiving LMWH (OR 1.69 [95% CI 1.46 to 1.96]), indirect factor Xa inhibitors (OR 1.62 [95% CI 1.13 to 2.26]), direct factor Xa inhibitors (OR 1.55 [95% CI 1.35 to 1.78]), and warfarin (OR 1.33 [95% CI 1.14 to 1.55]) were at a significantly higher risk of hematoma formation.

CONCLUSIONS: The use of aspirin for deep vein thrombosis prophylaxis after TKA is associated with a significantly lower risk of undergoing MUA and hematoma formation, without increasing the clotting risk profile, than more potent anticoagulants.