Thromboembolic and infectious complication risks in TKA and UKA: evidence from a Japanese nationwide cohort

Introduction: Total knee arthroplasty (TKA) and unicompartmental knee arthroplasty (UKA) are widely used to treat knee osteoarthritis. TKA significantly contributes to long-term pain relief and joint function improvement, while UKA offers faster recovery and reduced early complications. However, TKA and UKA complication risks, aside from conditions such as deep vein thrombosis, have not been thoroughly investigated. This study compares the in-hospital complication risks of TKA and UKA using a nationwide Japanese database. Methods: A retrospective cohort study was conducted using data from the Japanese Diagnosis Procedure Combination (DPC) database, spanning from April 2016 to March 2023. A total of 259,319 knee arthroplasty cases (TKA: 228,595; UKA: 30,724) were analyzed. Propensity score matching (1:1) was used to adjust for age, sex, comorbidities, and surgical factors, resulting in 30,591 matched pairs. Multivariable logistic regression analyses assessed the risks of complications, including deep vein thrombosis, pulmonary embolism, and surgical site infections. Results: Deep vein thrombosis is frequently observed as a complication with a high incidence rate. Even after propensity score matching, the incidence remained significantly higher in the TKA group (8.8%) compared with the UKA group (6.1%) (p < 0.0001). TKA was associated with significantly higher risks of deep vein thrombosis (odds ratio (OR): 1.467, 95% confidence interval (CI) 1.380–1.560, p < 0.0001), pulmonary embolism (OR: 1.709, 95% CI 1.182–2.470, p = 0.0044), and surgical site infection (OR: 1.512, 95% CI 1.277–1.790, p < 0.0001) compared with UKA. UKA showed lower risks of cognitive dysfunction, pneumonia, transfusion requirements, and shorter hospital stays. However, patients who underwent UKA had a higher risk of periprosthetic fractures. Conclusions: This study highlights the distinct risk profiles of TKA and UKA, emphasizing the need for tailored surgical decision-making. UKA offers advantages in reducing complications for specific patient populations. Strengthening prophylactic measures is crucial for effectively managing thromboembolic and infectious complications in patients undergoing TKA.