ARDEPARIN (LOW-MOLECULAR-WEIGHT HEPARIN) VS GRADUATED COMPRESSION STOCKINGS FOR THE PREVENTION OF VENOUS THROMBOEMBOLISM - A RANDOMIZED TRIAL IN PATIENTS UNDERGOING KNEE SURGERY

Background: Deep vein thrombosis is common in patients undergoing majo r knee surgery. Static graduated compression stockings effectively pre vent venous thrombosis in general surgery. Because of the demonstrated prophylactic efficacy of pneumatic compression in knee surgery, the s imilar efficacy of static graduated compression and pneumatic compress ion in neurosurgery, and the easier use of static graduated compressio n in knee surgery, graduated static compression stockings were used as the control arm in our clinical trial. Although low-molecular-weight heparin had been shown to be effective in general surgery and hip repl acement, its efficacy was unproved in knee surgery. Methods: A double- blind, randomized trial compared the combination of low-molecular-weig ht heparin and graduated compression stockings with graduated compress ion stockings alone in patients undergoing major knee surgery. Patient s received either ardeparin (Normiflo) (low-molecular-weight heparin), 0.005 mL/kg (50 anti-Xa U/kg), or placebo. Both were administered sub cutaneously twice daily commencing 12 to 24 hours after surgery and co ntinued for 14 days or until discharge, if sooner. Both study groups w ore graduated compression stockings. Bilateral venography was performe d on day 14, or sooner if the patient was ready for discharge. Results : One hundred twenty-two patients were allocated to receive ardeparin and 124 received placebo. Ninety-six patients in the ardeparin group a nd 103 in the placebo group had evaluable venograms. Deep vein thrombo sis was detected in 28 patients in the ardeparin group and in 60 in th e placebo group. Proximal deep vein thrombosis was detected in two pat ients who received ardeparin and 16 who received placebo. One patient in each group, both of whom did not have venography, experienced pulmo nary embolism. Thus, deep vein thrombosis or pulmonary embolism was de tected in 29 (29.9%) of the 97 patients in the ardeparin group and in 61 (58.7%) of the 104 patients in the placebo group, a relative risk r eduction of 49% (P<.001). The rate of major bleeding in the ardeparin group was 2.5%, compared with 2.4% in the placebo group. Conclusion: A rdeparin administered postoperatively twice daily is effective and saf e for the prevention of venous thrombosis in patients undergoing major knee surgery. Whereas graduated compression stockings have been shown to be effective prophylactic agents in general surgery and neurosurge ry, they have little effect in knee surgery.