Allogeneic Transfusion Rate and Related Factors in Primary Total Knee Arthroplasty

  Objective  To evaluate the transfusion rates and identify perioperative factors associated with allogeneic blood transfusion (AllTx) after primary total knee arthroplasty (TKA) with routine use of low-molecular-weight heparins.

  Methods  We retrospectively studied the transfusion rate of 1165 consecutive patients who underwent primary TKA between January 2005 and December 2011. Totally 34 independent variables were analyzed in 617 primary unilateral TKAs without autologous blood predonation for requirement of AllTx. Multiple regression analysis model was used to identify risk factors associated with perioperative blood transfusion.

  Results  Overall, 58.2%(678/1165) of patients required AllTx. The median number of units transfused was 2.7 U (range:1 to 13 U). The AllTx rate was 40.0% (278/695) in unilateral TKA procedures and 85.1% (400/470) in one-stage bilateral TKA procedures. Univariate analysis demonstrated the risk of transfusion was independentlypredicted by the patients' age at surgery (P < 0.0001), preoperative hematocrit(P < 0.0001), preoperative hemoglobin concentration (P < 0.0001), American Society of Anesthesiologists (ASA) score ≥ 3 (P=0.004), surgical time (P=0.004), and tourniquet time (P=0.050). Multivariate Logistic regression analysis confirmed significant relationship between allogeneic blood transfusion and age (P < 0.0001), preoperative hemoglobin(P < 0.0001), and surgical time (P < 0.0001).

  Conclusions  AllTx rate is high in TKA procedures, especially in one-stage bilateral TKA procedures. Patient's age, preoperative hemoglobin level, and surgical time are helpful in identifying high-risk patients who require postoperative blood transfusion.