Effect of a Topical Thrombin–Carboxymethyl Starch Hemostatic Agent on Perioperative Hemoglobin Course: A Propensity Score-Matched Study

Background and Objectives: With contemporary blood management strategies substantially reducing transfusion rates after total knee arthroplasty (TKA), conventional endpoints such as transfusion incidence and estimated blood loss may have limited sensitivity for evaluating adjunctive hemostatic interventions. As postoperative anemia evolves dynamically over time, hemoglobin kinetics and cumulative anemia burden may offer more informative measures of treatment effect. This study evaluated whether implementation of a topical thrombin–carboxymethyl starch hemostatic agent within a standardized modern blood management protocol was associated with smaller early postoperative hemoglobin decline and lower cumulative anemia burden after TKA. Materials and Methods: In this single-center, retrospective, pre–post observational study, consecutive patients aged 50 years or older undergoing primary unilateral TKA for osteoarthritis before and after implementation of a thrombin–carboxymethyl starch topical hemostatic agent were compared. Perioperative management was otherwise standardized and unchanged. Patients were matched 1:1 using propensity scores derived from eight prespecified covariates. Co-primary endpoints were hemoglobin change from baseline to postoperative day 1 and day 2, and cumulative anemia burden quantified by the area under the hemoglobin-deficit curve from POD 0 to POD 13 was assessed as a key secondary endpoint. Results: Of 564 patients assessed for eligibility, 328 met the inclusion criteria, and 70 propensity score-matched pairs were included in the final analysis. Unless otherwise specified, the outcomes reported below were analyzed in these 70 matched pairs. In the matched cohort, the intervention group had a lesser hemoglobin decrease at postoperative day (POD) 1 than the control group (2.12 ± 0.97 vs. 2.42 ± 0.98 g/dL), corresponding to a paired mean difference of 0.30 g/dL (95% CI, 0.08–0.52; p = 0.008). The between-group difference at POD 2 was not statistically significant (paired mean difference, 0.15 g/dL; 95% CI, −0.03 to 0.33; p = 0.10). The area under the hemoglobin-deficit curve from POD 0 to POD 13 was lower in the intervention group (18.6 ± 5.2 vs. 21.3 ± 5.6 g/dL × day), with a paired mean difference of 2.7 g/dL × day (95% CI, 0.9–4.5; p = 0.004). Estimated total blood loss, formula-derived hidden blood loss, and transfusion rates did not differ significantly between groups. Conclusions: Use of a thrombin–carboxymethyl starch topical hemostatic agent was associated with modest attenuation of early postoperative hemoglobin decline and lower cumulative anemia burden after TKA, without significant differences in estimated blood loss or transfusion occurrence. Hemoglobin kinetics and cumulative anemia burden may provide complementary outcome measures in contemporary low-transfusion practice, although these findings should be interpreted cautiously given the observational design and low transfusion event rate.