Introduction and Aims: Reinfusion drains have been used to decrease the need for blood transfusion following total knee replacement. The aim of this study was to evaluate the degree of activation of platelets and leucocytes in both the blood that has been salvaged after total knee arthroplasty and the patients’ blood following reinfusion.

Method: A prospective series of 24 consecutive patients undergoing a primary total knee replacement in a case-control study were investigated. Post-operatively 12 patients received salvaged blood reinfusion and as a control, 12 patients underwent TKA with a standard drain. The reinfusion was initiated four hours after the operation. Blood samples were taken from all patients at three and five and a half to six hours post-operatively. A third sample was acquired in the treatment group from salvaged blood after reinfusion. Platelet, platelet-leucocyte and leucocyte activation markers were studied in both the drainage blood and the patients’ blood following reinfusion.

Results: Comparison between platelet, platelet-leucocyte and leucocyte activation markers in patients’ circulation prior to reinfusion compared to salvaged blood showed that almost all markers were significantly increased in salvaged blood. For example the platelet activation markers P-selectin (p< 0.01), Factor V (p< 0.01), CD40L (p< 0.01) and platelet derived microparticles (p< 0.01) were all significantly increased in the drainage blood. All studied platelet-leukocyte and leucocyte activation particles were also significantly increased. Following re-infusion of autologous salvaged blood there was no statistically measurable effect on activation markers of patients’ circulating platelets and leucocytes, but there was a slight drop in platelet count in the reinfused group compared to the control group. Levels of prothrombin fragment F 1+2 increased in the reinfused group compared to control indicating either activation of coagulation or simply the effect of addition of the high levels present in the salvage blood.

Conclusion: Blood from reinfusion drains showed a significant increase in activation of platelets and leukocytes indicating activation of coagulation. The reinfused blood did not lead to a difference in platelet and leukocyte activation but a decrease in platelets and an increase in fragment F1+2 suggests the possibility of activation of coagulation.

Introduction and Aims: Decreasing blood loss during total hip replacement (THR) remains a challenge for the orthopaedic surgeon. This study investigated the effects of the antifibrinolytics aprotinin and epsilon aminocaproic acid (EACA) against placebo on blood loss during primary total hip replacement. Their safety and mechanism of action was also investigated.

Method: Forty-five patients undergoing primary unilateral total hip arthroplasty were randomised to receive an infusion of either aprotinin, EACA, or placebo. Intra- and post-operative blood loss was measured, as was the rate of blood transfusion and changes in haemoglobin concentration. Clinical examination and duplex ultrasound was used in all patients to detect thrombotic events. All patients were assessed clinically six weeks post-op to detect adverse events. Platelet function was assessed using P-selectin, Platelet-monocyte aggregates (PMA) and factor V/Va levels. D-dimer activity was recorded as an indicator of fibrinolysis. Non-parametric statistical analysis was employed in the interpretation of results.

Results: There was no difference in demographics or pre-operative platelet function between the groups with the exception of the EACA group which had a lower pre-operative haemoglobin concentration. Intra-operative blood loss was significantly lower in the aprotinin group compared to placebo (p=0.01), similarly there was also a reduction in intra-operative blood loss in the EACA group but this did not reach statistical significance. Post-operative bleeding from closed suction drains was markedly reduced for both aprotinin (60%, p=< 0.01) and EACA (53%, p=< 0.001) compared to placebo. Markedly less haemoglobin was lost in drains in both antifibrinolytic groups, with aprotinin showing a 77% (p=< 0.0001) and EACA a 73% reduction (p=< 0.001) in post-operative haemoglobin loss. Despite this, no difference in the rate of blood transfusion was observed between groups. Total hip arthroplasty surgery led to the activation of platelets as evidenced by P-selectin, PMA and factor V/Va levels. However, platelet function was not affected by either aprotinin or EACA. Both antifibrinolytics showed a similar increase in D-dimer levels indicating a similar efficacy in inhibiting fibrinbolysis. There were no DVTs, PEs or infections recorded in the study, and no increase in adverse events was seen with the use of antifibrinolytics.

Conclusion: Infusion of either aprotinin or EACA reduces blood loss after primary THA. Both agents are equally effective and have a favourable safety profile. The two drugs inhibit fibrinolysis in a similar fashion, and this action appears to be independent of platelets.