Prevention of Deep Vein Thrombosis after Major Knee Surgery - A Randomized, Double-Blind Trial Comparing a Low Molecular Weight Heparin Fragment (Enoxaparin) to Placebo

Abstract

SummaryConsecutive patients undergoing knee arthroplasty or tibial osteotomy at four participating hospitals received either enoxaparin, 30 mg subcutaneously every 12 h (n = 66) or an identicalappearing placebo (n = 65). All study medications started the morning after the operation and were continued up to a maximum of 14 days. Patients underwent surveillance with 125I-fibrinogen leg scanning and impedance plethysmography. Bilateral contrast venography was performed routinely at Day 14 or at time of discharge, if sooner. Deep vein thrombosis was detected by venography in 35 of 54 patients (65%) in the placebo group and in 8 of 41 patients in the enoxaparin group (19%), a risk reduction of 71%, P <0.0001. For the entire study group, deep vein thrombosis was detected by either venography of non-invasive tests in 37 of 64 patients (58%) in the placebo group and in 11 of 65 patients (17%) in the enoxaparin group, a risk reduction of 71%, P <0.0001. Proximal vein thrombosis was found in 19% of the placebo patients and in none of the enoxaparin patients, a risk reduction of 100%, P <0.001. Bleeding complications occurred in 5 of 65 patients (8%) in the placebo group and in 4 of 66 patients (6%) in the enoxaparin group, P = 0.71. There were no differences in the amount of blood loss, minimum hemoglobin levels and number of units of packed red cells given between the two treatment groups. We conclude that a fixed dose regimen of enoxaparin, started post-operatively, is an effective and safe regimen for reducing the frequency of deep vein thrombosis after major knee surgery.

Prevention of VTE in Orthopedic Surgery Patients

“…To estimate untreated bleeding risk, we fi rst determined the median major bleeding event rate from the placebo (or graduated compression stockings [GCS]) arm of LMWH trials and the Pulmonary Embolism Prevention (PEP) trial (subgroup that did not receive any heparin) because those trials were more recent. [30][31][32][33][34][35][36][37][38][39] [Section 1.3.1] Schematic of estimated incidence rates for LMWH and no prophylaxis for major orthopedic surgery used for this guideline. Additional example data are from observational studies (dashed line), which usually represents a cumulative incidence rate resulting from high rates of prophylaxis in the fi rst 7 to 14 days and low rates or no prophylaxis during the extended prophylaxis period.…”

“…LMWH 5 low-molecular-weight heparin. [31][32][33][34][35][36][37][38][39]47,48 and HFS. 49,50 Our analysis included all studies of LMWH vs no prophylaxis whether GCS were used in both groups because this would not affect the relative risk observed for LMWH.…”

Outpatient thromboprophylaxis after hip or knee surgery: discrepancies and concerns

“…3 Nevertheless, these concerns led the American Academy of Orthopaedic Surgeons to develop alternative guidelines, 4 which are based on data supporting the reduction of clinical outcomes, namely pulmonary emboli, rather than all venous thromboembolism events.…”

Profilaxia do tromboembolismo venoso em cirurgia ortopédica

“…On the other hand, the incidence of more severe bleeding occurred in 6% of the placebo group, and in 8% of the enoxaparin group, without statistical significance (p = 0.71) (1) . In some countries, like the United States, this reality has created increasingly rigid demands, in the requirement to adopt mechanisms to protect patients in conditions of risk.…”