Blood Transfusion in the Age of Tranexamic Acid: Who Needs a Type and Screen Before Total Knee Arthroplasty?

Tranexamic acid (TXA) has reduced, but not eliminated, blood transfusions surrounding total knee arthroplasty (TKA). Identifying risk factors for transfusion remains important for risk reduction and type and screen (T and S) optimization.

We retrospectively reviewed 7,254 patients who underwent primary, unilateral TKA and 307 patients who underwent primary bilateral TKA between January 2014 and January 2023, who received perioperative TXA and had preoperative hemoglobin (Hgb) values. We compared demographics, baseline Hgb levels, and surgical details between patients who were and were not transfused. Data were analyzed utilizing multivariate regressions and receiver operating characteristic analyses. A total of 172 unilateral TKA patients (2.4%) received perioperative transfusions, with 170 (2.3%) receiving postoperative transfusions and two (0.03%) receiving intraoperative transfusions. There were 26 bilateral TKA patients (8.5%) who received postoperative transfusions with no documented intraoperative transfusions.

For unilateral TKA, the risk of transfusion demonstrated an inverse correlation with preoperative Hgb levels, a bimodal association with body mass index, and a direct correlation with American Society of Anesthesiologists class and estimated blood loss (EBL) on multivariate testing. The receiver operating characteristic analyses demonstrated an optimal Hgb cutoff of 12.1 g/dL for predicting transfusion. The transfusion rate below Hgb of 12.1 g/dL was 6.6%, compared to a rate of 1.4% above this Hgb threshold. Below Hgb of 11 g/dL, the transfusion rate was 11.1%, while for Hgb between 11 and 12 g/dL, the transfusion rate was 4.6%.

Transfusion is rare in unilateral TKA when TXA is used and preoperative Hgb is ≥ 12.1 g/dL, challenging universal T and S. Patients who have Hgb less than 11.0 g/dL and bilateral TKA patients remain at higher risk. Risk factors such as Hgb between 11 and 12 g/dL, body mass index, American Society of Anesthesiologists, and EBL may predict transfusion risk and need for T and S.

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