Introduction: Extensive blood loss related to knee arthroplasty is quite normal and many patients require blood transfusions. Surgery and the use of pneumatic tourniquets lead to an increase in the activity of the fibrinolytic system, which in turn may accentuate the blood loss. Drugs that inhibit the fibrinolytic system may thus be used to reduce blood loss. Tranexamic acid (TA) acts by binding to one of the enzymes at the start of the coagulation cascade, so inhibiting the fibrinolytic system. A concern is that this inhibition may have the side effect of increasing thromboembolic disease, a common complication of joint replacement surgery. We aimed to confirm the reductions in blood loss and to assess the impact of TA usage on clinical and sub-clinical DVT.
Method: We performed a prospective, randomised, double blind, controlled trial, using patients due to undergo primary unilateral total knee arthroplasty. Patients were randomised to receive either 15 mg/kg of tranexamic acid or a similar volume of normal saline at the time of cementing of the prosthesis. Perioperative blood loss was recorded and patients were screened for DVT with duplex ultrasound assessment of both legs on the fifth post-operative day.
Results: A statistically significant (p=0.006) decrease in blood loss in the early post-operative period was noted in the group receiving tranexamic acid. This was not associated with a significant difference in total blood loss (p=0.55) or in transfusion requirements. There was no of evidence in DVT in either group on duplex ultrasound screening of the lower limbs.
Interpretation: One injection of 15 mg/kg of tranexamic given at the time of cementing the prosthesis in total knee arthroplasty, before deflation of the tourniquet, significantly decreases the amount of blood loss in the early post-operative period. The treatment was not associated with an increase in thromboembolic complications.