Low molecular weight heparin prophylaxis in total knee arthroplasty - The answer

Venous thrombosis continues to be a major risk after total knee arthroplast y. Without prophylaxis, the prevalence of deep vein thrombosis is as high a s 84 %, with proximal occurrence as high as 20 %. Of more concern is the oc currence of pulmonary embolism as high as 7%, with fatal pulmonary embolism as high as 0.7%. This high prevalence mandates that prophylaxis for thromb oembolic disease be used for patients undergoing total knee arthroplasty. L ow molecular weight heparin has been studied extensively and is safe and ef fective prophylaxis after total knee arthroplasty. Low molecular weight hep arins have a predictable dose response, offer high bioavailability at low d oses, and produce linear pharmacokinetics. It has a half-life of approximat ely 4.5 hours providing effective dosing every 12 to 24 hours with rapid an tithrombotic action. Routine pharmacologic prophylaxis with low molecular w eight heparin seems to be effective in decreasing the occurrence of venous thromboembolism. However, venographic prevalence of deep vein thrombosis am ong patients undergoing total knee arthroplasty and receiving prophylaxis r emains substantial at 30.6%. Prophylaxis with low molecular weight heparin beyond hospitalization may be indicated with decreased hospital stays, alth ough studies have not been convincing that extended outpatient prophylaxis for more then 7 to 10 days is necessary.