Clinical Outcome of Different Postoperative Prophylactic Strategies on Symptomatic Venous Thromboembolism after Total Knee Arthroplasty.

Introduction: The objective of this study was to evaluate the use of different post-operative prophylactic strategies on the rates of symptomatic venous thromboembolic events (VTE) incidence after primary total knee arthroplasty (TKA).

Methods: A retrospective study of patients who underwent primary TKA procedure was performed from January 2015 through July 2020. Outcomes examined prophylaxis medication used during inpatient and outpatient care, amount of medication, length of medication, complications occurring within 90 days post-operatively, including symptomatic VTE (deep venous thrombosis (DVT), and pulmonary embolism (PE)), gastrointestinal (GI) bleeding requiring medical attention, change in management protocols after post-operative complications, and mortality.

Results: In total, 5,663 cases were included (mean age 66 ± 10 years, mean BMI 34.1 ± 7.1kg/m²). The overall post-operative complication rate was 0.9% (DVT: 0.5%, PE: 0.3%, VTE: 0.04%, and GI bleeding: 0.09%). Enoxaparin use as inpatient anticoagulation medication was reduced significantly (67% vs. 13%, p < 0.001), and apixaban was increased significantly (6% vs. 49%, p < 0.001). Average hospital stays were reduced significantly among the years (3 ± 2 days vs. 2 ± 1 days, p < 0.001), and complication rates were not significantly different between the five years (~1%, p < 0.001). Most post-operative complications occurred on either aspirin 325 mg (36%) or apixaban (26%). However, the relative risk ratio results indicating that utilization of warfarin, rivaroxaban, and aspirin 81 mg as outpatient anticoagulation medication were more likely to increase the risk of symptomatic VTE incidence compared to other anticoagulants. The average time of complication detected was 21 ± 21 days (range: 1 - 87 days). More than 54% of complication events occurred after the patient had completed their medication (enoxaparin, rivaroxaban, and apixaban).

Conclusions: The observed incidence of symptomatic VTE in this study was similar to previous studies regardless of the type of post-operative inpatient or outpatient prophylaxis prescribed. The ultimate choice of prophylaxis should remain with the treating physician and their knowledge of a particular patient's medical history.