Thromboembolic complications were not different between intravenous and epidural analgesia after unilateral knee arthroplasty under neuraxial anesthesia: a propensity-score matched analysis

BACKGROUND: We aimed to compare thromboembolic (TE) complications between intravenous and epidural analgesia after unilateral total knee arthroplasty (TKA) under neuraxial anesthesia. METHODS: In this retrospective study, patients who received spinal anesthesia (SA) and intravenous patient-controlled analgesia (IV-PCA) were allocated to the SA-IV group, and those who received combined spinal-epidural (CSE) anesthesia and epidural PCA were allocated to the CSE-E group. Primary outcome was composite incidence of in-hospital TE events defined as myocardial infarction, stroke, peripheral artery occlusion, pulmonary embolism, or deep vein thrombosis. Secondary outcomes were general complications and pain score. After propensity score matching, outcomes were compared using generalized estimating equation. RESULTS: Among 1,244 cases from 2016 to 2022 at a tertiary hospital, 321 patients in SA-IV and 214 patients in CSE-E were analyzed after matching. The incidence of TE complications was comparable between SA-IV and CSE-E groups [0.9% (n = 3) vs. 2.8% (n = 6); odds ratio (OR) 1.88, 95% confidence interval (CI) 0.89-10.57; p = 0.08]. There were no differences in general complications, delirium, falls, or bedsores. In the CSE-E group, transient motor weakness was more frequent (OR 2.70, 95% CI 9.27-451.78; p < 0.001), and the number of days to joint exercise initiation was higher. However, pain score after TKA was significantly lower in the CSE-E group [5(3-6) vs. 3(2-5); p < 0.001]. CONCLUSION: In this retrospective analysis, the incidence of TE complications after TKA under neuraxial anesthesia was not significantly different between intravenous and epidural analgesia. Epidural analgesia was associated with lower pain intensity, higher incidence of motor weakness, and late initiation of exercise.