Thromboprophylaxis with enoxaparin for total knee replacement: An observational, retrospective and multicentre study comparing starting the treatment before and after the operation

Objective: The low molecular weight heparins are the first option for the prophylaxis of venous thromboembolic disease in major orthopaedic surgery. The time of starting their administration is controversial. The aim of this study was to evaluate the efficacy and safety of enoxaparin in patients subjected to total knee replacement comparing the starting of it before and after the surgery. Methods: An observational, retrospective and multicentre study of normal clinical practice to determine the incidence of symptomatic deep venous thrombosis and/or pulmonary thromboembolism in total knee replacement surgery. Thromboprophylaxis was normal practice in each centre. Patients were included if they received the first dose of 40 mg/24 h of enoxaparin either 12 h (+/- 2 h) before the surgery (G-PRE) or between 6 and 12 hours after the surgery (G-POST). The main safety objective was haemorrhage. A multivariate logistic regression analysis was performed to determine the real influence of each variable. Results: Data was collected from 2014 patients, of whom 1440 were included for the analysis of efficacy (782/1440, 54% of the G-PRE and 658/1440, 46% of the G-POST). The mean incidence of symptomatic thrombotic events was 1.67% (24/1440). The incidence of deep venous thrombosis in the G-PRE was 1.15% compared to 1.22% in the G-POST (P=.569 after multivariate analysis) and the incidence of pulmonary thromboembolism was 0.51 compared to 0.76%, respectively (P=.582 after multivariate analysis). A total of 1422 patients were included for the safety analysis. There was significant bleeding in 59/788 of the G-PRE and in 35/634 of the G-POST (7.49% compared to 5.52%, respectively, P=.138). Conclusions: These results suggest that thromboprophylaxis with enoxaparin (40 mg/24 h sc) in patients subjected to total knee replacement surgery has a similar safety and effective profile when it is given 12 hours before the surgery or between 6 and 12 hours afterwards. (C) 2011 Sociedad Espanola de Anestesiologia, Reanimacion y Terapeutica del Dolor. Published by Elsevier Espana, S.L. All rights reserved.