Abstract
This study was performed to examine the hypothesis that the rate of allogeneic blood transfusion in patients who did not predeposit an autologous blood transfusion before single-anesthetic bilateral total knee arthroplasty (TKA) would be noninferior to that in patients who did predeposit blood. METHODS: We assessed the number of allogeneic transfusions required in 338 patients undergoing single-anesthetic bilateral TKA with a preoperative hemoglobin level of ≥11.0 g/dL. All TKAs were performed by a single surgeon according to the same operative and postoperative protocol. All patients received a combination of intravenous and intra-articular tranexamic acid. Neither a pneumonic tourniquet nor a drain was used. The difference in the risk of allogeneic transfusion between patients without and with autologous blood predeposit was compared with a noninferiority margin of 10 percentage points. RESULTS: Allogeneic transfusion was required in 1 (0.5%) of 194 patients who predeposited autologous blood and 3 (2.1%) of 144 patients who did not predeposit blood. The difference in risk was -1.6 percentage points (95% confidence interval, -4.1 to 1.0 percentage points); the confidence interval did not include the noninferiority margin and included zero. CONCLUSIONS: In single-anesthetic bilateral TKA, allogeneic transfusion requirements in patients who did not predeposit autologous blood were noninferior to those in patients who predeposited blood. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.