Weight-Based Enoxaparin Dosing and Real-Time Dose Adjustment in Orthopaedic Trauma

The rates of Venous thromboembolism (VTE) after orthopedic surgery are as high as 40-60%
without prophylactic measures. Enoxaparin, a low-molecular-weight heparin, produces an
anticoagulant effect by binding antithrombin, thereby accelerating antithrombin's
inactivation of coagulation factor Xa (FXa), thus decreasing the likelihood of clot
formation. Despite standard dosing enoxaparin prophylaxis, VTE rates in post-operative
orthopedic trauma patients remain as high as 12.2%.The investigators will examine enoxaparin
pharmacokinetics and test whether a clinical protocol for real-time enoxaparin dose
adjustment can favorably alter the proportion of patients with in-range anti-Factor Xa (aFXa)
levels. Outcomes will include peak and trough steady-state aFXa levels in response to
standard and escalated doses of enoxaparin and the incidence of venous thromboembolism and
bleeding events post-surgery. In the trauma and orthopaedic populations, patients with low
initial aFXa levels are significantly more likely to develop deep venous thrombosis. Thus,
this study has important implications for appropriate enoxaparin dose magnitude and
frequency, and may ultimately help to decrease the substantial morbidity and mortality
associated with post-operative VTE.