BACKGROUND: Outpatient total knee arthroplasty (TKA) has quickly grown in popularity, largely driven by policy shifts and the recent coronavirus disease 2019 (COVID-19) pandemic. The aim of this study was to compare 30-day complications between outpatient TKA (oTKA) versus inpatient TKA (iTKA) before and after the COVID-19 pandemic to elucidate the effect of the pandemic on utilization and short-term outcomes. METHODS: Patients who underwent primary TKA between 2008 and 2021 were identified through Current Procedural Terminology codes in a national database. Propensity score matching controlled for demographic and comorbid differences. The rates of 30-day postoperative complications were compared, and risk factors for adverse events were identified. RESULTS: A total of 533,503 patients were identified, with 31,905 (6.0%) undergoing oTKA and 501,598 (94.0%) undergoing iTKA. Despite a rise in the frequency of oTKA over time, the rate of any adverse event (AAE) in the oTKA cohort remained significantly lower than that of iTKA (P <
0.001) from 2008 to 2021. This difference was maintained when comparing oTKA to iTKA AAE rates in the pre-COVID (2008 to 2019) and post-COVID (2020 to 2021) periods (P = 0.001 and 0.004, respectively). Postoperative transfusions were less frequent in oTKA cases for all years (P <
0.001) and were less frequent in postpandemic oTKA cases compared to prepandemic oTKA (P = 0.027). When controlling for all other factors, the outpatient operative setting emerged as a risk-reducing factor for AAE in both pre-COVID and post-COVID cohorts. In contrast, age, body mass index, and a history of chronic obstructive pulmonary disease increased the risk of experiencing an adverse event. CONCLUSIONS: Despite a rapid increase in the utilization of oTKA after the onset of the COVID-19 pandemic, 30-day adverse events did not increase and remained lower than that of iTKAs overall. Our findings indicate that oTKA is associated with lower short-term (30-day) complications.