Tranexamic acid reduces early post-operative blood loss after total knee arthroplasty: A prospective randomised controlled trial of 29 patients

Abstract

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.

Introduction

Knee arthroplasty is usually performed using a leg tourniquet to minimise blood in the operative field and reduce blood loss. Despite this, drainage of around 1200–1500 ml post-operatively is quite normal [1]. Many patients require blood transfusions, with the associated risks (transfusion reactions, blood-borne infection and an increased risk of post-operative infection) [2] and costs.

The use of pneumatic tourniquets lead to an increase in the activity of the fibrinolytic system (a naturally existing enzymatic system that regulates clot and thrombus formation in the body). Paradoxically, this may accentuate surgical blood loss [3], [4], [5]. Drugs, such as tranexamic acid (TA), that inhibit the fibrinolytic system reduce blood loss [6], [7], [8], [9], [10], [11], [12], [13]. A concern amongst surgeons and anaesthetists is that this inhibition may have the side effect of increasing thromboembolic disease, a common complication of joint replacement surgery [14], [15].

At the time of the study, several prospective, randomised, controlled trials had investigated whether use of TA could reduce blood loss and transfusion requirements [6], [7], [8], [9], [11]. None reliably screened all patients for deep venous thrombosis (DVT) [6], [7], [9], [16] and some only if clinical suspicion existed [6], [7], [8], [9], [16] so the question of an increase in thromboembolic disease has not been adequately addressed.

We aimed to confirm the reductions in blood loss with a single dose of tranexamic acid and to assess the impact of TA usage on clinical and sub-clinical DVT.