Dalteparin in total knee arthroplasty

I read with great interest a recent publication by Bell and colleagues¹ about factors affecting perioperative about factors affecting perioperative blood loss and transfusion rates in primary total knee arthroplasty. They reported on the effect of dalteparin use and the effect of patient sex, tourniquet release in total knee arthroplasty and house staff turnover months on blood loss and transfusion rates.¹ The controversy about the prevention of venous thromboembolism by use of dalteparin and the risk of blood loss still exists. Indeed, the use of dalteparin for preventive purpose is confirmed for its cost effectiveness.² Dranitsaris and colleagues² recently reported the acceptable results from cost-utility analysis using dalteparin in arthroplasty. According to a report by Dahl and colleagues,³ combined administration of Dextran 70 did not increase perioperative blood loss compared with Dextran 70 alone in major orthopedic surgery. These results are discordant with those in the report by Bell and colleagues.¹ Whether the identified correlation by Bell and colleagues¹ is by chance is unknown. Indeed, in their study, the reduction of hemoglobin level and the rate of allogeneic blood transfusions were the 2 main measured parameters.¹ There is no direct evidence about changes in any coagulation profiles that might lead to the exact conclusion about the effect of dalteparin. Nevertheless, the amount of perioperative blood loss has not been systematically assessed. Indeed, a database review also poses limitations in data acquisition, and there might be underrecorded cases with other underlying conditions leading to the change of hemoglobin levels and the requirement for postoperative blood transfusion.