Chisari E, Yu AS, Yayac M, et al. - In this study, true facility costs of patients undergoing outpatient total knee arthroplasty (TKA) were compared with those undergoing unicompartmental knee arthroplasty (UKA). Between 2018 and 2019, researchers examined a consecutive series of 2,310 outpatient TKA and 231 UKA patients. A time-driven activity-based costing algorithm was applied to estimate facility costs. They compared implants, supplies, medications, and personnel costs between outpatient TKA and UKA patients. They conducted a multivariate analysis to control for confounding medical and demographic variables. Outpatient TKA has increased facility costs to the hospital, despite equivalent reimbursement from Centers for Medicare and Medicaid Services (CMS) as UKA. According to the findings, when compared with UKA, CMS should consider appropriately reimbursing outpatient TKA for the additional personnel costs.