PROPHYLAXIS FOR THE PREVENTION OF VENOUS THROMBOEMBOLISM AFTER TOTAL KNEE ARTHROPLASTY - A COMPARISON BETWEEN UNFRACTIONATED AND LOW-MOLECULAR-WEIGHT HEPARIN

We compared the efficacy and safety of low-molecular-weight heparin wi th that of low-dose unfractionated heparin in the prevention of venous thromboembolism after total knee arthroplasty in a prospective, rando mized, multicenter trial. One hundred and eighty-five patients were ra ndomly assigned to two groups: ninety-two received low-molecular-weigh t heparin (forty milligrams of enoxaparin the evening before the opera tion and once a day subsequently) and ninety-three received unfraction ated heparin (5000 international units the evening before the operatio n and three times a day thereafter). The prophylasis was continued unt il bilateral ascending venography nas performed six to nine days after the operation or, if venography was not done, until the eighth postop erative day. Venography revealed a prevalence of deep-vein thrombosis of 27 per cent (twenty-five of ninety-three patients) in the group tha t received unfractionated heparin and 23 per cent (twenty-one of ninet y-two patients) in the group that received low-molecular-weight hepari n. The difference was not significant (p = 0.6). Five patients (5 per cent) who received unfractionated heparin and 3 patients (3 per cent) who received low-molecular-weight heparin had a deep-vein thrombosis i n the proximal veins. Two patients who received unfractionated heparin and one who received low-molecular-weight heparin had clinical sympto ms suggestive of a pulmonary embolism. None of these three patients ha d a positive ventilation-perfusion scan. There were no deaths, major b leeding episodes, or wound hematomas necessitating operative intervent ion or discontinuation of the anticoagulation in the series. On the ba sis of these findings, we believe that enoxaparin is safe and efficien t as prophylaxis against venous thromboembolism after total knee arthr oplasty.