Clinical Impact of Routine Complete Blood Counts Following Total Knee Arthroplasty

Background: Routine laboratory studies are generally obtained following total knee arthroplasty (TKA), and often continued daily until discharge. This study aims to investigate the utility and cost-effectiveness of complete blood count (CBC) tests following TKA. Methods: Retrospective review identified 484 patients who underwent primary TKA under a tourniquet at a single institution. Preoperative and postoperative CBC values were collected along with demographic data, use of tranexamic acid (TXA), and transfusion rates. Logistic regression models were calculated for all variables. Results: Twenty-five patients required transfusion following TKA (5.2%). Patients requiring transfusion had significantly lower preoperative hemoglobin compared to patients who did not require transfusion (11.47 vs 13.58 g/dL, P =.005). Risk of transfusion was 5.2 times higher in patients with preoperative anemia (95% confidence interval 2.90-9.35, P <.001). Without TXA, patients were 2.75 times more likely to receive transfusion (95% confidence interval 1.43-5.30, P <.001). An average of 2.9 CBC tests were collected per patient who did not receive medical intervention, costing a total of $144,773.80 in associated hospital charges ($316.10 per patient). Conclusion: Ensuring quality, cost-effective patient care following total joint arthroplasty is essential in the era of bundled payments. Routine postoperative CBCs do not add value for patients with normal preoperative hemoglobin who receive TXA during TKA performed under tourniquet. Patients who are anemic preoperatively or do not receive TXA should obtain a postoperative CBC test. Daily CBCs are unnecessary if the first postoperative CBC does not prompt intervention.