Blood loss and transfusion risk in single-stage bilateral UKA compared with bilateral TKA

Knee arthroplasty is associated with a variable risk of blood transfusion depending on the surgical technique, with a higher risk for total knee arthroplasty (TKA) than for unicompartmental knee arthroplasty (UKA). Although the safety of single-stage bilateral procedures has now been established, the risk of transfusion for single-stage bilateral TKA is high at approximately 20% whereas the risk of transfusion for bilateral UKA is only 2%. Although this difference appears to be significant, to date there is no study comparing transfusion rates between the two procedures when performed as single stage surgeries. Reducing transfusion risk would support the use of unicompartmental knee arthroplasty, since transfusion is a known risk factor for postoperative complications, especially infections. The objective of this study was to compare blood loss and transfusion rate between these two techniques and to identify risk factors.

A multicenter retrospective study was conducted in four French centers including 277 patients who underwent single-stage bilateral knee arthroplasty between January 2021 and December 2023: 149 bilateral TKA procedures and 128 bilateral UKA procedures. The parameters analyzed included preoperative hemoglobin, hemoglobin levels at postoperative day 1 (D1) and day 3 (D3), blood loss volume, number of transfused red blood cell units, use of a pneumatic tourniquet or suction drain, early complications, and patient satisfaction. Statistical comparisons were performed using Student's t-test and the chi-square test, with a significance threshold set at p < 0.05.

Preoperative hemoglobin levels were slightly higher in the UKA group (14.5 g/dL vs 14.2 g/dL; p = 0.038). The mean hemoglobin decrease at D3 was significantly greater in the TKA group (4.8 g/dL vs 2.1 g/dL; p < 0.0001), as was blood loss volume (1.2 L vs 0.5 L; p < 0.0001). The transfusion rate was 20% in the TKA group versus 0% in the UKA group (p < 0.0001). The use of a suction drain was associated with significantly higher blood loss in both groups. No association was found between transfusion risk and age or ASA score. The rate of early complications was 6% in the TKA group and 1.6% in the UKA group, with no statistical difference. Patient satisfaction exceeded 94% in both groups. In multivariate analysis, lower preoperative hemoglobin level (OR ≈ 0.52, p = 0.011) and use of a suction drain (OR ≈ 11.3, p < 0.001) were independently associated with an increased risk of transfusion.

Single-stage bilateral total knee arthroplasty is associated with significantly greater blood loss and transfusion risk than bilateral unicompartmental knee arthroplasty. These results support the value of unicompartmental arthroplasty in reducing perioperative morbidity in the treatment of disabling knee osteoarthritis. However, patient-related factors appear to play a decisive role in bleeding risk, and additional studies will need to exclude these factors to clarify the influence of the surgical technique.

III; Retrospective comparative study.