Risk factors for ecchymosis in patients receiving rivaroxaban for thromboprophylaxis after total knee arthroplasty: a retrospective cohort study

What is known and objective: Ecchymosis of the limb is commonly seen after total knee arthroplasty (TKA) when using anticoagulants for thromboprophylaxis, but it is unknown which factors may predispose patients to an increased risk. The aim of this study was to evaluate risk factors for ecchymosis in patients receiving rivaroxaban after TKA.

Methods: A retrospective, single-centre cohort analysis was conducted. The electronic medical records of patients admitted to the Department of Orthopedics during January 2018 to December 2019 and who received rivaroxaban 10 mg daily after TKA were reviewed for documentation of ecchymosis. Baseline demographics, laboratory values and surgical information were included for analysing their relationship with ecchymosis.

Results and discussion: A total of 227 patients were included in the study. Among them, 54 patients (23.8%) developed ecchymosis, and 173 did not. The ecchymosis group had a higher proportion of patients with a body weight >60 kg [83.33% vs. 50.00%, p = 0.0004] and hypertension [61.11% vs 41.46%, p = 0.0304]. The ecchymosis group also had a higher BMI [26.04 ± 2.71 kg/m² vs 24.52 ± 3.18 kg/m² , p = 0.0066] mean arterial pressure (MAP) recorded from post-operation day 1 to day 3 [105.21 mmHg vs 91.52 mmHg, p = 0.0003]. However, serum albumin concentrations before surgery [3.85 g/dL vs. 4.20 g/dL, p = 0.0225] and on post-operation day 3 [3.50 g/dL vs. 3.91 g/dL, p = 0.0370] were lower in the ecchymosis group. Serum haemoglobin on post-operation day 3 was also lower [10.07 g/dL vs. 11.57 g/dL, p = 0.0459]. Five risk factors for ecchymosis were identified by binary logistic regression: mean MAP (from POD1 to POD3) (OR=2.901, 95% CI: 2.522-3.293, p < 0.001), BMI (OR=2.513, 95% CI: 1.929-3.011, p < 0.001), history of hypertension (OR=2.661, 95% CI: 1.272-4.535, p = 0.032), post-surgery serum albumin level (OR=0.848, 95% CI: 0.735-0.977, p = 0.023) and post-surgery serum haemoglobin level (OR=0.943; 95% CI: 0.898-0.990, p = 0.018).

What is new and conclusion: The present analyses identified that BMI, history of hypertension, mean MAP (POD1 to POD3), post-surgery serum albumin level and post-surgery serum haemoglobin level were independent risk factors for rivaroxaban-related ecchymosis in patients who underwent TKA. These factors should be considered and optimized before starting rivaroxaban therapy.