Are Risk Factors for Postoperative Significant Hemorrhage following Total Knee Arthroplasty Potentially Modifiable? A Retrospective Cohort Study

SIMPLE SUMMARY: Total knee arthroplasty is the treatment of choice for end-stage osteoarthritic knees. However, the surgery-associated postoperative hemorrhage remains a big concern. Most of previous studies have defined meaningful postoperative bleeding as blood loss > 500 mL or a hemoglobin (Hb) drop > 20 g/L. The aims of this study were to identify factors that closely related to significant postoperative hemorrhage and whether the identified factors could be modified. Five factors that closely related to more hemorrhage were identified; they were male patients, old age patients, patients without using tranexamic acid (TXA), patients under general anesthesia, and platelet count. Of these five factors, the number of platelets, use of TXA, and spinal anesthesia are perhaps modifiable to limit hemorrhage. These three potentially modifiable factors need to be taken into consideration when making both the preoperative care and anesthesia plan by surgeons and anesthesiologists, especially in male and aged patients. ABSTRACT: Total knee arthroplasty (TKA) is the treatment of choice for end-stage osteoarthritis (OA) of the knee, because it alleviates pain and restores function of the knee. However, TKA-associated hemorrhage and subsequent anemia remain a concern. Most previous studies have defined meaningful postoperative bleeding as blood loss > 500 mL or hemoglobin (Hb) drop > 20 g/L. Therefore, we defined significant hemorrhage as a postoperative Hb drop more than 20 g/L in this study, and we investigated possible risk factors related to significant hemorrhage in TKA and whether these risk factors are modifiable. This retrospective study was conducted through a comprehensive review of the perioperative records of patients with OA of the knee who underwent TKA between January 2009 and December 2015 at our hospital. Patients were allocated into two groups: patients in Group A had their Hb drop ≤ 20 g/L; patients in Group B had their Hb drop > 20 g/L. Factors analyzed included sex, age, body mass index (BMI), the American Society of Anesthesiologists (ASA) classification, comorbidities, preoperative platelet count, use of tranexamic acid (TXA), operation time, and type of anesthesia. A total of 3350 patients met the criteria for analysis, with 1782 patients allocated to Group A and 1568 patients to Group B. Five independent risk factors for significant hemorrhage were identified: male sex (odds ratio(OR), 1.29; 95% confidence interval(CI), 1.08–1.53; p = 0.005), age (OR, 1.02; 95% CI, 1.01–1.03; p = 0.001), use of TXA (OR, 0.39; 95% CI, 0.34–0.45; p < 0.001), spinal anesthesia versus general anesthesia (OR, 0.71; 95% CI, 0.56–0.90; p = 0.004), and preoperative platelet count (OR, 0.96; 95% CI, 0.93–0.98; p = 0.001). Of these identified risk factors, preoperative platelet count, use of TXA, and spinal anesthesia are modifiable. These potentially modifiable risk factors need to be taken into consideration when making both the perioperative care and anesthesia plan by surgeons and anesthesiologists, especially in patients at risk of significant hemorrhage.