THEKNE-02240; No of Page 1 The Knee xxx (2016) xxx
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Letter to editor “Intravenous versus intra-articular tranexamic acid in total knee arthroplasty: A double-blinded randomized controlled noninferiority trial” Keywords: Tranexamic acid Total knee arthroplasty Transfusion Blood loss Lower limb swelling
To the Editor, We recently read the published article “Intravenous versus intraarticular tranexamic acid in total knee arthroplasty: A double-blinded randomized controlled noninferiority trial” with great interest and congratulate the authors for sharing their experience with the Orthopedic community . It is a well-conducted trial with a good number of patients. However we have some doubts regarding the results presented by the author and we would appreciate a response to our queries. Firstly, we have doubts regarding the hemoglobin balance method used by the authors. Instead of ﬁxed day values at day 1 and day 4, the lowest value should have been chosen to calculate the true loss. In our experience, and also in most studies a day 2 to day 3 value is usually the lowest and is chosen by most surgeons for calculation . Why the authors chose the fourth day value is not clear and we think this might actually give lower ﬁgures of actual loss. Most studies have shown hidden loss to be twice the visible loss [2–4]. However, to our surprise, the hidden loss in the present series was nearly seven times that in the intra-articular group. (Drain loss 100 ml, total loss 799 ml giving hidden loss of 699 ml). This is not in consensus with the current available literature. What, in the authors' opinion, is the cause of such a high hidden loss in their series? The authors mention that trigger for transfusion is a hemoglobin less than eight, or 10 in cases of symptoms of anaemia symptoms. However in group IV, the range of postoperative hemoglobin mentioned is 10.2 g% to 11.7 g%. Still there were two transfusions in this group without even a single patient having a hemoglobin of less than 10. What were the reasons for transfusion in these patients? Also, the values of total loss presented by the authors are on the lower side to most literature. Most randomized trials have a total calculated loss of over 1000 ml [2,3]. We believe that there is some discrepancy in calculation regarding the amount of total loss presented by the authors. For example, the intra-articular group had a mean drop of 3.1 g of hemoglobin, and considering a total blood volume on an average to be four to ﬁve liters, the mean total loss should be around 920 DOI of original article: http://dx.doi.org/10.1016/j.knee.2015.09.004.
to 1150 ml, but the results presented are below 800 ml. How do the authors explain this? Were the drains clamped after surgery? Clamping of drains by itself has been shown to reduce blood loss and may act as a confounding factor. The authors in their method have mentioned that the study was stratiﬁed according to the surgeons, however if there was a difference in the stratiﬁed results of the surgeons it is not mentioned. We also have a comment on drug dosage. Fibrinolytic response after surgical trauma is known to be biphasic with an increased activity during the ﬁrst three hours, followed by a shutdown that peaks at about 24 h. So an injectable dose in postoperative is effective. This is supported in the literature where it is shown that a combination of pre-op, intra-operative and post-operative regimen may have the highest effectiveness in reducing blood transfusion compared to other methods . Further we believe that the method of drug delivery in intra-articular group may be improved by retrograde injection through the drain after closure. This would increase the contact time of drug with target tissue. Once again, we would like to congratulate the authors on an excellent conducted trial. We agree with them that both methods are effective in reducing the blood loss after total knee arthroplasty. However, the dosage, timing and method of intra-articular drug delivery remain a matter of debate. And further trials may be required to answer these matters. References  Chen JY, Chin PL, Moo IH, Pang HN, Tay DKJ, Chia S-L, et al. Intravenous versus intraarticular tranexamic acid in total knee arthroplasty: a double-blinded randomised controlled noninferiority trial; 2015. http://dx.doi.org/10.1016/j.knee.2015.09.004.  Gomez-Barrena E, Ortega-Andreu M, Padilla-Eguiluz NG, Pérez-Chrzanowska H, Figueredo-Zalve R. Topical intra-articular compared with intravenous tranexamic acid to reduce blood loss in primary total knee replacement. J Bone Joint Surg Am Dec 2014;96(23):1937–44.  Sehat KR, Evans R, Newman JH. How much blood is really lost in total knee arthroplasty? Correct blood loss management should take hidden loss into account. Knee Jul 1 2000;7(3):151–5.  Prasad N, Padmanabhan V, Mullaji A. Blood loss in total knee arthroplasty: an analysis of risk factors. Int Orthop 2007;31:39–44.  Maniar RN, Kumar G, Singhi T, Nayak RM, Maniar PR. Most effective regimen of tranexamic acid in knee arthroplasty: a prospective randomized controlled study in 240 patients. Clin Orthop Relat Res 2012;470(9):2605–12.
Anil Mehtani Department of Orthopaedics, Lady Hardinge Medical College, Shaheed Bhagat Singh Marg, New Delhi 110002, India Jatin Prakash Assistant Professor, Central Institute of Orthopaedics, Safdarjung Hospital and Vardhaman Mahavir Medical College, New Delhi, India Corresponding author at: H-19/82, Sec-7, Rohini 110085, India. E-mail address: [email protected]
6 February 2016 Available online xxxx
http://dx.doi.org/10.1016/j.knee.2016.02.009 0968-0160/© 2016 Elsevier B.V. All rights reserved.
Please cite this article as: Mehtani A, Prakash J, Letter to editor “Intravenous versus intra-articular tranexamic acid in total knee arthroplasty: A double-blinded randomized con, Knee (2016), http://dx.doi.org/10.1016/j.knee.2016.02.009