[Thrombosis prophylaxis in orthopedic surgery].
At Trondheim University Hospital, prophylaxis against thromboembolism after orthopaedic surgery was changed from dextran 70 to low molecular weight heparin in 1992. We wanted to assess whether the frequency of thromboembolic complications has fallen after this change of procedure and to search for any indication that prophylaxis should be prolonged from two to six weeks. Our register showed 97 cases (0.76%) with thromboembolism during the first 12 weeks after 12,711 operations during the dextran 70 period; 99 cases (0.54%) after 18,368 operations during the low molecular-weight heparin period (p < 0.05). A more thorough search identified 121 (0.66%) thromboembolic complications during the low molecular-weight heparin period; 2.2% among patients with total hip arthroplasty and 1.5% among patients with hip fractures. In these two groups, 19 (0.71%) thromboembolic complications were diagnosed during the third to sixth postoperative week. If all these complications had been avoided by prolonging prophylaxis to six weeks, each would have cost around NOK 200,000. Among patients with a diagnosed thromboembolic complication one hip fracture patient and no hip arthroplasty patients died during the third to sixth postoperative weeks. We conclude that there has been a significant fall in thromboembolism following the change from dextran 70 to low molecular-weight heparin. The frequency of thromboembolism and fatal lung embolus is so low during the third to sixth postoperative weeks that prophylaxis beyond two weeks is unwarranted.