Perioperative outcomes of total and unicompartmental knee arthroplasty in patients with Type 2 diabetes mellitus: A propensity score–matched analysis

Purpose: Type 2 diabetes mellitus is a common comorbidity in patients undergoing knee arthroplasty and is associated with higher risks of thromboembolic, infectious and postoperative cognitive complications. The extent to which total knee arthroplasty (TKA) and unicompartmental knee arthroplasty (UKA) differ in short-term perioperative risk among patients with Type 2 diabetes remains unclear. Methods: We performed a retrospective cohort study using Japan's nationwide Diagnosis Procedure Combination database, including patients with Type 2 diabetes who underwent primary TKA or UKA for osteoarthritis between April 2016 and March 2023. Outcomes included deep vein thrombosis, pulmonary embolism, surgical site infection, postoperative delirium, blood transfusion, length of hospital stay and discharge destination. A 1:1 propensity score (PS)-matched analysis was performed using demographic and clinical characteristics. Additional PS-matched and interaction analyses were performed in patients without Type 2 diabetes and in the overall cohort, respectively. Results: Among 263,838 eligible patients, 49,373 with Type 2 diabetes underwent TKA and 5,801 underwent UKA; 5783 matched pairs were analysed. After matching, TKA was associated with higher incidences of deep vein thrombosis (odds ratio [OR] 1.46; 95% confidence interval [CI] 1.29-1.66) and postoperative delirium (OR 2.35; 95% CI 1.39-3.96), longer hospital stay, lower rates of direct discharge to home and greater transfusion volume. Similar differences were observed in patients without Type 2 diabetes, and no significant interactions between diabetes status and surgical procedure were observed for deep vein thrombosis or postoperative delirium. Conclusions: Among patients with Type 2 diabetes undergoing knee arthroplasty, UKA was associated with a more favourable short-term perioperative profile than TKA. Similar differences in deep vein thrombosis and postoperative delirium were observed in patients without Type 2 diabetes, with no significant interaction by diabetes status, suggesting that these differences were not specific to diabetes. Level of Evidence: Level III.